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General Category => Yeast and Fermentation => Topic started by: Philbrew on January 12, 2015, 07:28:25 PM

Title: Right RPM for stir plate?
Post by: Philbrew on January 12, 2015, 07:28:25 PM
What's the right RPM for stir plate?  Does the size of the starter matter?  I don't have one yet.  Just doing my homework.  Would a small external aquarium pump plumbed to circulate and splash starter work as well?
Title: Re: Right RPM for stir plate?
Post by: denny on January 12, 2015, 08:02:04 PM
It doesn't matter at all.  As long as the stir bar is moving and the yeast and wort are mixing, it's fast enough.  Contrary to the myth, a bigger vortex gains you nothing.
Title: Re: Right RPM for stir plate?
Post by: TMX on January 12, 2015, 10:09:34 PM

It doesn't matter at all.  As long as the stir bar is moving and the yeast and wort are mixing, it's fast enough.  Contrary to the myth, a bigger vortex gains you nothing.

Big vortex = bragging rights
Title: Re: Right RPM for stir plate?
Post by: duboman on January 12, 2015, 10:20:41 PM
The vortex makes no difference as mentioned, as for the aquarium pump idea, not sure. While o2 is beneficial for the starter I'm not sure if it wouldn't be detrimental pumping into the starter for the 48-72 hours it would take to ferment out. Maybe someone else has a thought on that?
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 12, 2015, 11:28:33 PM
It doesn't matter at all.  As long as the stir bar is moving and the yeast and wort are mixing, it's fast enough.  Contrary to the myth, a bigger vortex gains you nothing.
So it's not so much the aeration as it is the mixing that gets you the good yeast growth of a stir plate vs. intermittent shaking, etc.?
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 13, 2015, 12:01:27 AM
I'm more and more convinced that a stirplate only gets the yeast up into the wort, its not doing much at all for O2. So, the O2 comes from shaking or oxygenation, or whatever method. If this is so, slow stir is fine, so is fast stir.
Title: Re: Right RPM for stir plate?
Post by: denny on January 13, 2015, 12:20:03 AM
It doesn't matter at all.  As long as the stir bar is moving and the yeast and wort are mixing, it's fast enough.  Contrary to the myth, a bigger vortex gains you nothing.
So it's not so much the aeration as it is the mixing that gets you the good yeast growth of a stir plate vs. intermittent shaking, etc.?

Correct.
Title: Re: Right RPM for stir plate?
Post by: JT on January 13, 2015, 12:36:01 AM
The vortex makes no difference as mentioned, as for the aquarium pump idea, not sure. While o2 is beneficial for the starter I'm not sure if it wouldn't be detrimental pumping into the starter for the 48-72 hours it would take to ferment out. Maybe someone else has a thought on that?
A microbiologist @ Wyeast confirmed this for me a year ago. 
After reaching terminal gravity, adding oxygen only keeps the yeast active with nothing to eat so they burn through their energy reserves.  Refrigeration when the wort hits terminal gravity is the best way to go.  From my testing a 2 liter starter only takes about 18 hours to finish out around the ideal temp of 70.  I never go past 30 hours on a plate.  Usually just 24. 
Title: Re: Right RPM for stir plate?
Post by: duboman on January 13, 2015, 12:49:41 AM
This makes sense and I'm not sure why I typed 48-72 hours as my starters are done in the 18-24 range as well and then placed in the fridge. Perhaps its because in know some people just go longer for no apparent gain.  That was why I was ques iining using an aerator for the entire time in lieu of a stir plate in possibly achieving the same results.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 01:00:02 AM
JT, you were given bad information.  Adding oxygen after fermentation is complete causes yeast cells to enter diauxic shift where they consume ethanol as their carbon source.   

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3133784/

"The preferred source of carbon and energy for yeast cells is glucose. When yeast cells are grown in liquid cultures, they metabolize glucose predominantly by glycolysis, releasing ethanol in the medium. When glucose becomes limiting, the cells enter diauxic shift characterized by decreased growth rate and by switching metabolism from glycolysis to aerobic utilization of ethanol. "


In the absence of post-fermentation dissolved oxygen, yeast cells enter a quiescent state after storing glycogen.  The cells also undergo morphological changes where their walls thicken in preparation for quiescence, which is why one does not want to allow a starter to ferment out before pitching it.

Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 01:16:39 AM
JT, you were given bad information.  Adding oxygen after fermentation is complete causes yeast cells to enter diauxic shift where they consume ethanol as their carbon source.   

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3133784/

"The preferred source of carbon and energy for yeast cells is glucose. When yeast cells are grown in liquid cultures, they metabolize glucose predominantly by glycolysis, releasing ethanol in the medium. When glucose becomes limiting, the cells enter diauxic shift characterized by decreased growth rate and by switching metabolism from glycolysis to aerobic utilization of ethanol. "


In the absence of post-fermentation dissolved oxygen, yeast cells enter a quiescent state after storing glycogen.  The cells also undergo morphological changes where their walls thicken in preparation for quiescence, which is why one does not want to allow a starter to ferment out before pitching it.

i presume everything you say is factual. but the question that lingers, is that if making a starter and pitching or even attempting to significantly slow fermentation by cold crashing is the preferred or optimal way to do it, how can it be explained that good results are obtained by letting a starter finish, cold crashing, decanting and then pitching? seems like a lot of us have done it this way over the years and for me personally, I cant say its caused any issues. just curious I guess.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 01:45:37 AM
I'm not discounting or disputing any of your scientific facts. I'm just questioning if my beer will taste any different in a blind test with a starter fully fermented and one not.


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Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 01:51:14 AM
i presume everything you say is factual. but the question that lingers, is that if making a starter and pitching or even attempting to significantly slow fermentation by cold crashing is the preferred or optimal way to do it, how can it be explained that good results are obtained by letting a starter finish, cold crashing, decanting and then pitching? seems like a lot of us have done it this way over the years and for me personally, I cant say its caused any issues. just curious I guess.

There's a difference between acceptable results and optimal results.  Cold crashing and decanting at the end of the exponential phase ensures that the yeast cells are in optimal health when pitched into a batch of wort while maximizing the use of the medium.  The cells still have ergosterol and unsaturated fatty acid (UFA) reserves, and the cell membranes have not yet had to deal with increasing levels of metabolites and ethanol.  In effect, yeast cells that are pitched at the end of the exponential phase are healthy and ready go with minimal replenishment.  Cold crashing and decanting at the end of exponential phase mimics top-cropping at high krausen, which is how  top-cropping breweries crop.  Top-cropping at high krausen is why top-cropping breweries can re-pitch almost indefinitely.  Harvey's in the UK has been re-pitching the same top-cropped yeast culture for over fifty years.

One thing that I left out in my first reply is that the ergosterol and UFA reserves that are built by mother cells while O2 is still in solution are shared with all of their daughter cells.  Peak viable yeast biomass is reached at the end of the exponential phase. From that point forward, reproduction is for replacement only, which means that we are wasting ergosterol and UFA reserves while exposing the cells to substances that take their toll on cell membrane health.  While there is a slight increase in biomass by allowing the starter to ferment out, that increase is composed of non-viable cells.  The goal when propagating a yeast culture is to increase the viable cell count, not produce ethanol.   The only cell count that matters when propagating a culture is the viable cell count.
Title: Re: Right RPM for stir plate?
Post by: JT on January 13, 2015, 01:54:05 AM
JT, you were given bad information.  Adding oxygen after fermentation is complete causes yeast cells to enter diauxic shift where they consume ethanol as their carbon source.   

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3133784/

"The preferred source of carbon and energy for yeast cells is glucose. When yeast cells are grown in liquid cultures, they metabolize glucose predominantly by glycolysis, releasing ethanol in the medium. When glucose becomes limiting, the cells enter diauxic shift characterized by decreased growth rate and by switching metabolism from glycolysis to aerobic utilization of ethanol. "


In the absence of post-fermentation dissolved oxygen, yeast cells enter a quiescent state after storing glycogen.  The cells also undergo morphological changes where their walls thicken in preparation for quiescence, which is why one does not want to allow a starter to ferment out before pitching it.
I don’t think it was bad info, I’m likely not stating it correctly.   :-\  Keeping the yeast on the stir plate and in optimal temps allows it to chow down on the less desirable food source.   From the same article “Cells in the diauxic shift and stationary phase are stressed by the lack of nutrients and by accumulation of toxic metabolites, primarily from the oxidative metabolism…”  So they’re still eating, but nothing good for them.   

Being that beer is a mix of art and science, I think scientific studies can be misleading for brewers when they just focus one aspect: yeast health.  Case in point: it is better from a yeast health perspective to pitch an active starter, but from a tasty beer perspective it isn’t always the best option, because the starter wort has undesirable flavors. 
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 02:02:43 AM
I would like to add that cold crashing at the end of the exponential phase reduces starter lead time from a couple of days to less than 24 hours when pitching a relatively fresh White Labs vial. This reduction in lead time means that a starter can be pitched the evening before one intends to brew, popped into one's refrigerator late morning the following day in preparation for decanting, and pitched late afternoon the following day.   
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 02:12:39 AM
Being that beer is a mix of art and science, I think scientific studies can be misleading for brewers when they just focus one aspect: yeast health.  Case in point: it is better from a yeast health perspective to pitch an active starter, but from a tasty beer perspective it isn’t always the best option, because the starter wort has undesirable flavors.


There's nothing art about fermentation.  Fermentation is an area of brewing that is bounded by science.  Fermentation is little more than controlled spoilage.

One does not have to wait until fermentation is complete to settle the yeast cells and decant.  I have yet to encounter a brewing strain that will not cease to ferment and start to sediment when placed into a refrigerator set at 3C to 4C, which is what the temperature at which the average home refrigerator is set in the United States.

If you want to get testimony from a convert, ask Jim about his experience with crashing, decanting, and pitching at the end of the exponential phase.
Title: Re: Right RPM for stir plate?
Post by: JT on January 13, 2015, 02:22:08 AM
Being that beer is a mix of art and science, I think scientific studies can be misleading for brewers when they just focus one aspect: yeast health.  Case in point: it is better from a yeast health perspective to pitch an active starter, but from a tasty beer perspective it isn’t always the best option, because the starter wort has undesirable flavors.


There's nothing art about fermentation.  Fermentation is an area of brewing that is bounded by science.  Fermentation is little more than controlled spoilage.

One does not have to wait until fermentation is complete to settle the yeast cells and decant.  I have yet to encounter a brewing strain that will not cease to ferment and start to sediment when placed into a refrigerator set at 3C to 4C, which is what the temperature at which the average home refrigerator is set in the United States.

If you want to get testimony from a convert, ask Jim about his experience with crashing, decanting, and pitching at the end of the exponential phase.
The art referred to in my post was in regards to the taste of beer with an entire starter pitched into it. 
At any rate we appear to agree here, crash earlier rather than later.  Looks like I can crash even earlier than I thought, which is fine by me.  I made a starter Friday night with WLP002, crashed it Saturday night in the fridge, decanted and pitched it Sunday around 5pm.  When I checked on it today at 6am it already had a helluva krausen on it and I have the temp controlled at 65. 
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 02:32:16 AM
I just leave on stir plate 18-24 hours and then put it in fridge. Mostly because I'm not home to pull it off earlier, and just throw it in fridge when I get home. Some yeast do need longer to floc, and since I decant I give myself the appropriate time for this before brew day.


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Title: Re: Right RPM for stir plate?
Post by: duboman on January 13, 2015, 02:53:22 AM
This is all well above my microbiological pay grade.... My question is when comparing scale of home brew pitch and commercial pitch, how relevant is the detail in all this?

I make the appropriate starter, ferment, crash, decant and pitch with proper aeration etal... The beer is really good
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 02:58:16 AM
I'd imagine most commercial is using slurry, not starters? My hunch is on the small scale side, starters fermented out vs partial likely not discernible - all other things considered like healthy appropriate quantity of yeast for the particular beer, good aeration of wort, proper fermentation temps, yeast nutrient, etc.


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Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 03:11:16 AM
Here's another tidbit.  I rarely decanted in the decade that I brewed before taking a hiatus from the hobby.  I started to decant religiously after I started using a stir plate because the supernatant (clear green beer) from a continuously stirred culture is just foul.  However, I since gone back to using well-shaken starters because I did not find that continuous stirring resulted in a significant improvement in performance, and I do not have to be as meticulous about decanting the supernatant with a well-shaken starter.   A well-shaken starter takes like unhopped beer instead of metabolite stew.
Title: Re: Right RPM for stir plate?
Post by: duboman on January 13, 2015, 03:21:19 AM
Right, but we are simply decanting and pitching the yeast, not the supernatant clear green beer.

I can't imagine that here is a discernable difference in 5-10 gallons of finished beer at home brew scale.
Title: Re: Right RPM for stir plate?
Post by: 69franx on January 13, 2015, 03:30:08 AM
Please clarify for me: the science says to refrigerate at end of exponential phase rather than when fully fermented. Exponential phase generally over 18-24 hours after pitching into starter? Or 18-24 hours after first signs of activity in the starter? What am I looking for to know that exponential phase is over? What changes will I see?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 03:31:34 AM
proper fermentation temps

I know that what I am about to say is going to go over like a lead balloon, but the "proper fermentation temperature" argument is way over overdone in modern home brewing.   Far too many new brewers are led to believe that they have to have a temperature-controlled fermentation chamber in order to make high-quality ales.  Anyone who is having to start 5-gallon ale fermentations in the high fifties/low sixties with extremely forgiving strains like BRY 96 (a.k.a. Balllentine "Beer," "Chico", Wy1056, WLP001, and US-05) in order to produce a clean tasting product has a house microflora or yeast management problem.  To this day, I do not start ale fermentations that low on purpose. In fact, I do not artificially attemper ale fermentations (I ferment in a below-grade unfinished basement).   What starting an ale fermentation that low does is hide yeast management and sanitation problems because it favors domesticated microflora.  If one is meticulous about yeast management, sanitation, and post-boil wort handling,  BRY 96 will produce a cleanly flavored product when started at 68F and allowed to ferment up into the low seventies.

I personally believe that all brewers, whether professional or amateur, should learn basic aseptic transfer technique.   The reason why I do so is because it has a ripple effect on how one approaches yeast management and propagation as well as brewing hygiene.
Title: Re: Right RPM for stir plate?
Post by: JT on January 13, 2015, 03:52:39 AM
Please clarify for me: the science says to refrigerate at end of exponential phase rather than when fully fermented. Exponential phase generally over 18-24 hours after pitching into starter? Or 18-24 hours after first signs of activity in the starter? What am I looking for to know that exponential phase is over? What changes will I see?
In my test, I transferred to a cylinder and used a hydrometer.  A 2 liter 1.040 starter was done 18 hours after pitching when run on a stir plate around 70 degrees. 
This was a throwaway batch of yeast used only for testing fermentation time to get me in the ballpark.  It is very possible that not all yeast would have the same result, but 2 liters isn't a lot of wort for the yeast to go through, so it doesn't take long. 
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 04:36:11 AM
Please clarify for me: the science says to refrigerate at end of exponential phase rather than when fully fermented. Exponential phase generally over 18-24 hours after pitching into starter? Or 18-24 hours after first signs of activity in the starter? What am I looking for to know that exponential phase is over? What changes will I see?

If we assume that a White Labs vial contains 100 billion viable cells when shipped, a relatively fresh vial contains 50 billion viable cells, the maximum cell densities for 1L and 2L starters are 200 billion cells and 400 billion cells respectively, and yeast cells bud every ninety minutes after the lag phase has been exited, then we are looking at two and three propagation periods for 1L and 2L starters under perfect conditions.  Adding one ninety minute propagation period to each count to account for cell death during propagation results in three cell division periods for a 1L starter and four cell division periods for a 2L starter.


propagation_time_for_a_1L_starter = lag_time_in_hours + (3 x 90 / 60) = lag_time_in_hours + 4.5
propagation_time_for_a_2L_starter = lag_time_in_hours + (4 x 90 / 60) = lag_time_in_hours + 6

The reason why the exponential phase (a.k.a. log phase) is called the exponential phase is because the cell count grows are a rate of 2n, where n is the number of 90 minute time periods that have elapsed since the end of the lag phase.

With that said, let's calculate how long it takes 200 billion cells to reach maximum cell density in a 5-gallon batch of wort.  Five gallons is roughly 19 liters (19,000 milliliters); hence, the cell count from a 200 billion cell 1L starter has to increase by a factor of 19.  Now, we are dealing with exponential, not linear growth; hence, the number of 90 minute time periods that are required to increase the cell count 19 fold is equal to log2(19), where log2 is the log base 2 function.  Most calculators do not support log2, but we can take the log2 of n by taking the log(n) over the log(2) (i.e., log(n)/log(2)); hence, log(19) / log(2) = 5 (rounded).   Five ninety minute replication periods after the lag phase has been exited should be enough time to reach maximum cell density.

Now, anyone who is following this thread closely has probably figured out that the phase over which we have the most control in a fermentation is the time spent in the lag phase.  By stepping a culture at the end of the exponential phase, we are pitching yeast cells that require very little in the way of replenishment. Hence, we will experience a shorter lag phase than we will if we pitch a culture that has reached quiescence because a quiescent culture has to undo the morphological changes it underwent in preparation for hard times.  A quiescent culture also has to replenish the ergosterol and UFA reserves that were spent post-exponential phase, which increases dissolved O2 requirements.

Here's another thing to think about when propagating a culture.  Bacteria cells divide every thirty minutes on average.  Hence, the bacteria cell count grows by a factor of 8 every time the yeast cell count grows by a factor of 2.  Add in the possibility of a shorter lag phase for house bacteria, and it should be painfully obvious why pitching at the end of the exponential phase is preferred to waiting until the culture has entered quiescence.


Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 11:55:32 AM

[/quote]
propagation_time_for_a_1L_starter = lag_time_in_hours + (3 x 90 / 60) = lag_time_in_hours + 4.5
propagation_time_for_a_2L_starter = lag_time_in_hours + (4 x 90 / 60) = lag_time_in_hours + 6
[/quote]

so a 4L starter = lag_time_in_hours + 12? so roughly 24hrs from pitch yeast in starter to cold crash is what you would do?
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 13, 2015, 12:58:09 PM
Regarding "ask Jim", First off, its an akward honor that my brewing would be referenced as any kind of benchmark. What I did a while back is put his method to the test. I oxygenated my starter wort, pitch a smack pack, and put it on the stirplate the day before brewing. At 18 hrs (which was moring of brew day) I moved it to the fridge. Its difficult to tell for sure on a stir plare but it looked to be at high krausen at that time. Once I was done brewing and had my wort chilled I decanted and pitched. At that point the starter had about 75% settled out, there was a pile of creamy yeast at the bottom and about a 2" layer of less floculant yeast in the column above it. I decanted all but about an inch of liquid, swirled that up and pitched. By the way, that starter smelled like lovely fresh bread rather than disgusting spent starter wort. That beer took off like a storm and made a really nice beer ahead of normal schedule.

From that I learned
1. Stir plates dont do much in the way of aeration. I used to not oxygenate my starters, I do now
2. The starter is to make healthy young recruits not battle weary vetrans.
3. The reason to decant is to keep nasty spent wort out of your beer, if you crash at high krausen there's less worry about that. Some folks pitch the whole shebang at high krausen, right?

My pitching method is
1. With a new smack pack, I make a starter the day before and crash it at 18hrs
2. If I'm stepping (like for my current Helles) I crash step 1 at 18hrs and step 2 at 18hrs.
3. If im repitching and I rebrew the day after racking the first beer I do a direct measure and repitch
4. if im rebrewing more than a day later I follow the same process as if it were a smack pack.

Im not claiming this is THE way to do things, its just my way.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 03:19:29 PM
so a 4L starter = lag_time_in_hours + 12? so roughly 24hrs from pitch yeast in starter to cold crash is what you would do?

No, you are treating cell growth as a linear process.  The cell count grows exponentially because each cell buds (divides) into two cells every growth period; hence, one additional growth period is required every time we double volume.

propagation_time_for_a_1L_starter = lag_time_in_hours + (3 x 90 / 60) = lag_time_in_hours + 4.5
propagation_time_for_a_2L_starter = lag_time_in_hours + (4 x 90 / 60) = lag_time_in_hours + 6
propagation_time_for_a_4L_starter = lag_time_in_hours + (5 x 90 / 60) = lag_time_in_hours + 7.5
propagation_time_for_an_8L_starter = lag_time_in_hours + (6 x 90 / 60) = lag_time_in_hours + 9
...


I suggested 12 to 18 hours in order to allow for sub-optimal growth conditions and starting yeast health.  The culture will often be ready to crash before 12 hours have elapsed when pitching a White Labs vial.  A White Labs vial contains an huge number of cells for the size of the medium into which it is being pitched when making a starter.

Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 03:24:54 PM
so a 4L starter = lag_time_in_hours + 12? so roughly 24hrs from pitch yeast in starter to cold crash is what you would do?

No, you are treating cell growth as a linear process.  The cell count grows exponentially because each cell buds (divides) into two cells every growth period; hence, one additional growth period is required every time we double volume.

propagation_time_for_a_1L_starter = lag_time_in_hours + (3 x 90 / 60) = lag_time_in_hours + 4.5
propagation_time_for_a_2L_starter = lag_time_in_hours + (4 x 90 / 60) = lag_time_in_hours + 6
propagation_time_for_a_4L_starter = lag_time_in_hours + (5 x 90 / 60) = lag_time_in_hours + 7.5
propagation_time_for_an_8L_starter = lag_time_in_hours + (6 x 90 / 60) = lag_time_in_hours + 9
...


I suggested 12 to 18 hours in order to allow for sub-optimal growth conditions and starting yeast health.  The culture will often be ready to crash before 12 hours have elapsed when pitching a White Labs vial.  A White Labs vial contains an huge number of cells for the size of the medium into which it is being pitched when making a starter.

ok got it. so for what you describe, if I pitch one vial of white labs in to 4L of wort, cold crash it at about 12hrs, and then compare the slurry of that starter to 4L of wort with one vial of white labs after 24hrs on stir plate before cold crash, the slurry volume and yeast count (i have no equipment to determine this) should be the same?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 03:34:36 PM
ok got it. so for what you describe, if I pitch one vial of white labs in to 4L of wort, cold crash it at about 12hrs, and then compare the slurry of that starter to 4L of wort with one vial of white labs after 24hrs on stir plate before cold crash, the slurry volume and yeast count (i have no equipment to determine this) should be the same?

The overall cell count may be different, but the viable cell count should be roughly the same.   Cells have be stained with methylene blue to test for viability. Dead yeast cells take up the stain and turn blue.  As I stated above, the only cell count that matters is the viable cell count.  Dead cells do not make beer.   
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 03:40:32 PM
ok got it. so for what you describe, if I pitch one vial of white labs in to 4L of wort, cold crash it at about 12hrs, and then compare the slurry of that starter to 4L of wort with one vial of white labs after 24hrs on stir plate before cold crash, the slurry volume and yeast count (i have no equipment to determine this) should be the same?

The overall cell count may be different, but the viable cell count should be roughly the same.   Cells have be stained with methylene blue to test for viability. Dead yeast cells take up the stain and turn blue.  As I stated above, the only cell count that matters is the viable cell count.  Dead cells do not make beer.

just wondering if you ever performed the test to count viable cells with the two scenarios.
Title: Re: Right RPM for stir plate?
Post by: denny on January 13, 2015, 04:31:50 PM
I know that what I am about to say is going to go over like a lead balloon, but the "proper fermentation temperature" argument is way over overdone in modern home brewing.   Far too many new brewers are led to believe that they have to have a temperature-controlled fermentation chamber in order to make high-quality ales.  Anyone who is having to start 5-gallon ale fermentations in the high fifties/low sixties with extremely forgiving strains like BRY 96 (a.k.a. Balllentine "Beer," "Chico", Wy1056, WLP001, and US-05) in order to produce a clean tasting product has a house microflora or yeast management problem.  To this day, I do not start ale fermentations that low on purpose. In fact, I do not artificially attemper ale fermentations (I ferment in a below-grade unfinished basement).   What starting an ale fermentation that low does is hide yeast management and sanitation problems because it favors domesticated microflora.  If one is meticulous about yeast management, sanitation, and post-boil wort handling,  BRY 96 will produce a cleanly flavored product when started at 68F and allowed to ferment up into the low seventies.

So how do you account for my experience of making distinctly better beer by using a procedure that you say isn't necessary?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 05:09:49 PM
just wondering if you ever performed the test to count viable cells with the two scenarios.


I ran the test a couple of times in the late nineties/early 00s, which is how I came to the conclusion that the science holds.   I sold my entire brewery and home lab when I left the hobby in 2003.   I have yet to purchase another microscope because I cannot come close to cost justifying the level of microscope that I want, and a microscope is not very useful in a home brewery.  I can learn what I need to know for quality control from plating cultures on different types of media.


The most useful tools that anyone who is interested in observing yeast behavior are one's senses, a writing implement, and a notebook (or the modern version of the latter two tools).  You would be surprised at how much you can learn about a particular yeast strain just by paying close attention to how it behaves during propagation and fermentation.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 05:10:43 PM
So how do you account for my experience of making distinctly better beer by using a procedure that you say isn't necessary?

Less than optimal yeast management and/or brewery hygiene.
Title: Re: Right RPM for stir plate?
Post by: denny on January 13, 2015, 05:12:09 PM
So how do you account for my experience of making distinctly better beer by using a procedure that you say isn't necessary?

Less than optimal yeast management and/or brewery hygiene.

I'm afraid I'm not smart enough to understand what you mean.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 05:52:36 PM
I'm afraid I'm not smart enough to understand what you mean.

What I am saying is that anyone who has to start ale fermentations in the high 50s/low 60s in order to produce a product that has a fermentation by-product profile that is indicative of the strain employed in fermentation is more than likely picking up wild microflora somewhere during yeast propagation and/or wort production.  It's no secret why mechanical refrigeration and the introduction of lager pure cultures made brewing on an industrial scale possible.  The temperature range at which lager fermentation occurs favors the pitched strain, lowering the possibility of a production crippling infection occurring.  That same thing can be said for ale fermentations that are started at artificially low temperatures.  The low starting temperature gives the pitched domesticated culture a competitive advantage over wild house microflora that may have been introduced during propagation and/or wort production. More often than not, off-flavors that occur when fermentation is held within a culture's optimal temperature range are the result of wild microflora, not the domesticate strain that was pitched.

I know that is difficult for many brewers to accept that their yeast management and/or brewery hygiene made need a little tweaking.  However, I have watched enough home brewers make a starter to know that most home brewer's handle cultures in a less than optimal manner.  Let me give you an example of a less than optimal yeast handling practice that I see repeated over and over again.  If I had a dollar for every home brewer that I have witnessed open a White Labs vial and pitch it into starter or pitch the slurry from a starter without first wiping the pouring surface with alcohol (or better yet flaming the pouring surface), I would be able to brew for several years for free.  When handling a culture, all pouring surfaces should be treated as if they are contaminated because a small infection can grow into a big infection during the exponential phase.  How a culture is handled when it is small can make a huge difference in the final product.  That's why I recommend that all brewers should learn how to perform basic aseptic transfer technique.   Learning how to propagate cultures in the small will absolutely change how a brewer approaches propagation in the large.
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 13, 2015, 06:09:17 PM
Here's another tidbit.  I rarely decanted in the decade that I brewed before taking a hiatus from the hobby.  I started to decant religiously after I started using a stir plate because the supernatant (clear green beer) from a continuously stirred culture is just foul.  However, I since gone back to using well-shaken starters because I did not find that continuous stirring resulted in a significant improvement in performance, and I do not have to be as meticulous about decanting the supernatant with a well-shaken starter.   A well-shaken starter takes like unhopped beer instead of metabolite stew.
It sounds like I may not need to buy a $100 stir plate right off the bat.
Does this sound like a OK plan for a 6 gal. batch of lager(SG 1.045)?:
Morning day 1) Pitch a smack-pac of 2124 Boh Lgr into 3 qt. of starter wort in a 1 gallon container.
Day 1)  shake every 60 min. and put in fridge after 12 hr.
Day 2)  decant top 2 qt. and add 3 new quarts of starter wort.  Shake every 60 min. and put in fridge after 12 hr.
Morning day 3)  Brew and when wort cooled to (50 F ??) pitch the whole gal of starter.

Any and all suggestion much appreciated.
Title: Re: Right RPM for stir plate?
Post by: morticaixavier on January 13, 2015, 06:15:35 PM
S. Cerv, While I agree that it's likely that most of us don't handle our yeast with enough care, are you saying that yeast don't produce off flavors of fusels, increased esters, phenols, etc at temps in the 70's? and every time that happens it's because of a minor contamination issue? That would be very surprising to me.

philbrew,

the missing piece is the maximum cell density S. Cerv mentioned. 3L would be about 600b cells, if you pitch those into another 3L you will end up with about 600b slightly older, less vigorous cells.

Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 13, 2015, 06:33:17 PM
Thanks Mort,
The MrMalty calculator says I need 340 B cells, so you are saying that I should be able to eliminate day 2.  Good news.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 13, 2015, 06:37:40 PM
Thanks Mort,
The MrMalty calculator says I need 340 B cells, so you are saying that I should be able to eliminate day 2.  Good news.

just a side note-you really never know what your starting count is, so I like to over shoot by about 10% with my starters. so perhaps 375-400B might be a good target.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 07:08:37 PM
It sounds like I may not need to buy a $100 stir plate right off the bat.
Does this sound like a OK plan for a 6 gal. batch of lager(SG 1.045)?:
Morning day 1) Pitch a smack-pac of 2124 Boh Lgr into 3 qt. of starter wort in a 1 gallon container.
Day 1)  shake every 60 min. and put in fridge after 12 hr.
Day 2)  decant top 2 qt. and add 3 new quarts of starter wort.  Shake every 60 min. and put in fridge after 12 hr.
Morning day 3)  Brew and when wort cooled to (50 F ??) pitch the whole gal of starter.

Any and all suggestion much appreciated.

You really do not need to shake the starter every 60 minutes.  What you need is a starter vessel that is at least three times the volume of the starter because head space is critical to aerating the wort. 
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 13, 2015, 07:35:48 PM
Thanks S. cere,
How often do I need to shake it?
Vessels larger than 1 gal. are hard to come by and harder to shake.  How about I cut the starter wort to 2 qts. and shoot some O2 from my cutting torch into the headspace before I shake?  Will that give me enough cells for a 6 gal. lager?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 07:38:46 PM
S. Cerv, While I agree that it's likely that most of us don't handle our yeast with enough care, are you saying that yeast don't produce off flavors of fusels, increased esters, phenols, etc at temps in the 70's? and every time that happens it's because of a minor contamination issue? That would be very surprising to me.

No, what I am saying is that having to start ale fermentations in the high 50s/low 60s in order to avoid off-flavors is a sign that there is something in the fermentation other than the pitched ale strain. Few ale strains require low sixties fermentation temperatures in order to produce their specified fermentation by-product profile.  Most of the non-specialty ale strains that are available home brewers do not start to misbehave in a major way until fermentation temperatures are well into the seventies if they are not stressed and wort composition is sound.

With that said, I have had BRY 96 mutate and become POF+ during serial repitching.  I thought that the change in performance was the result of house microflora infection the first time I encountered it.  However, I started to do research on the problem after it happened the second time.  Apparently, becoming POF+ is a common mutation for BRY 96, which is a relatively unstable yeast strain. 
Title: Re: Right RPM for stir plate?
Post by: denny on January 13, 2015, 08:06:40 PM
No, what I am saying is that having to start ale fermentations in the high 50s/low 60s in order to avoid off-flavors is a sign that there is something in the fermentation other than the pitched ale strain. Few ale strains require low sixties fermentation temperatures in order to produce their specified fermentation by-product profile.  Most of the non-specialty ale strains that are available home brewers do not start to misbehave in a major way until fermentation temperatures are well into the seventies if they are not stressed and wort composition is sound.

But that doesn't account for personal taste.  I don't start low because I get "bad" flavors from starting higher.  I do it because I prefer the flavor profile I get from fermenting at lower temps.  I'm afraid your scientific analysis doesn't take that into account.
Title: Re: Right RPM for stir plate?
Post by: duboman on January 13, 2015, 08:17:36 PM
No, what I am saying is that having to start ale fermentations in the high 50s/low 60s in order to avoid off-flavors is a sign that there is something in the fermentation other than the pitched ale strain. Few ale strains require low sixties fermentation temperatures in order to produce their specified fermentation by-product profile.  Most of the non-specialty ale strains that are available home brewers do not start to misbehave in a major way until fermentation temperatures are well into the seventies if they are not stressed and wort composition is sound.

But that doesn't account for personal taste.  I don't start low because I get "bad" flavors from starting higher.  I do it because I prefer the flavor profile I get from fermenting at lower temps.  I'm afraid your scientific analysis doesn't take that into account.
My thought as well. I feel that there is more to this whole conversation than the specific science/microbiology involved
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 13, 2015, 08:19:17 PM
No, what I am saying is that having to start ale fermentations in the high 50s/low 60s in order to avoid off-flavors is a sign that there is something in the fermentation other than the pitched ale strain. Few ale strains require low sixties fermentation temperatures in order to produce their specified fermentation by-product profile.  Most of the non-specialty ale strains that are available home brewers do not start to misbehave in a major way until fermentation temperatures are well into the seventies if they are not stressed and wort composition is sound.

But that doesn't account for personal taste.  I don't start low because I get "bad" flavors from starting higher.  I do it because I prefer the flavor profile I get from fermenting at lower temps.  I'm afraid your scientific analysis doesn't take that into account.
My thought as well. I feel that there is more to this whole conversation than the specific science/microbiology involved

+2.  I feel the same.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 13, 2015, 10:23:10 PM
But that doesn't account for personal taste.  I don't start low because I get "bad" flavors from starting higher.  I do it because I prefer the flavor profile I get from fermenting at lower temps.  I'm afraid your scientific analysis doesn't take that into account.

However, that's not how low temperature ale fermentation or temperature ramped fermentation is presented in this forum and others.  It's presented as a requirement for quality ale production.  A temperature-controlled fermentation chamber is one of the first things that I see promoted when a new brewer asks about gear and/or process improvement even though the brewer is fermenting ale.  No one even bothers to ask what the ambient temperature is in the brewer's fermentation room before offering the suggestion.  It's all about using refrigeration for a process that can be performed in the high sixties/low seventies range with excellent results, a temperature range that is easily met for most of the year in below grade basements in states that experience four seasons. The trick is picking the right yeast culture for the task at hand, not tricking the yeast culture into performing the task at hand.  Those who live in warm states have no choice, but to resort to forced attemperation.
Title: Re: Right RPM for stir plate?
Post by: Joe Sr. on January 13, 2015, 10:54:41 PM
I can agree that temp control tends to be over emphasized.  You do not need a fermentation fridge to make good beer.  You can make perfectly good beer at ambient temps, assuming your ambient temps are within the right range (I'd say not higher than 68) and that they remain stable.  I don't think it's best practice to ferment your ales in the 70s, though I've had that happen on occasion, but you can certainly make drinkable beer, even good beer if you've got a strain that can handle those temps.

I've seen newer brewers on this forum get worried about having to dump a beer because fermentation temps got into the 70s, without yet having tasted the beer.  That's no the relax, don't worry approach.

As a group, we tend to get obsessive about things and I think that keeping things simple is the best way for new brewers to get going.  Not everyone needs all the tricked out gadgets.  Not everyone needs a dedicated fermentation fridge.

However, I do think it's important for brewers to understand fermentation temperatures and the impact/effect of different temperatures.  Figure out what works for you and what you like.  I think we're all interested in obtaining consistent results and fermentation temperature control is important for consistent results (even if your temp control is simply a consistent ambient temp).

There is art to brewing, even if the foundation is science.  I'm no scientist, but I am a brewer.
Title: Re: Right RPM for stir plate?
Post by: erockrph on January 13, 2015, 11:55:05 PM
But that doesn't account for personal taste.  I don't start low because I get "bad" flavors from starting higher.  I do it because I prefer the flavor profile I get from fermenting at lower temps.  I'm afraid your scientific analysis doesn't take that into account.

However, that's not how low temperature ale fermentation or temperature ramped fermentation is presented in this forum and others.  It's presented as a requirement for quality ale production.  A temperature-controlled fermentation chamber is one of the first things that I see promoted when a new brewer asks about gear and/or process improvement even though the brewer is fermenting ale.  No one even bothers to ask what the ambient temperature is in the brewer's fermentation room before offering the suggestion.  It's all about using refrigeration for a process that can be performed in the high sixties/low seventies range with excellent results, a temperature range that is easy met for most of the year in below grade basements in states that experience four seasons. The trick is picking the right yeast culture for the task at hand, not tricking the yeast culture into performing the task at hand.  Those who live in warm states have no choice, but to resort to forced attemperation.

I will say that I believe pitching an appropriately-sized, healthy pitch of yeast is at least as important (if not more) than keeping your pitching temperature low. Outside of certain ale strains that produce a significant amount of flavor compounds (hefe strains and some [but not all] abbey-style strains), I get damn near the same result from most ale strains at the full range of ambient fermentation temps in my basement - regardless of whether that is 58F or 66F.
Title: Re: Right RPM for stir plate?
Post by: narcout on January 14, 2015, 05:03:56 AM
the maximum cell densities for 1L and 2L starters are 200 billion cells and 400 billion cells respectively

I wonder how close I am actually getting to those maximum cell densities. 

In the experiment discussed on page 140 of Yeast, when 100 billion cells were pitched into 2 liters of 1.036 wort at 70 degrees, the total cells after the starter was complete were only 205 billion.

When 100 billion cells were pitched into 4 liters of the same wort, the total cells after the starter was complete were only 276 billion. 

White and Zainasheff note that no oxygen was added and that the starters were not agitated.  I think they would have grown more cells had they done either of those things but how many more I have no idea.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 14, 2015, 06:09:50 PM
Two hundred billion cells is the theoretical maximum number of cells that can live in 1L of a liquid medium.  It does not mean that a 1L starter will automatically produce 200 billion cells.  The amount of extract and the average size of the yeast cells in the starter also play a role in the total cell count.  If I recall correctly, DeClerk stated that 1 gram of extract is required to produce 1 billion cells.  Whether or not that claim holds is an exercise unto itself.  Assuming that DeClerck is correct, we would need have 100 grams of DME in a 1L starter in order to grow 100 billion cells.   That's a specific gravity of 1.040.   As you have already mentioned, available oxygen plays a vital role because the ergosterol and UFAs that are synthesized while O2 is still in solution are shared with all of the daughter cells.  These compounds are vital to cell health because they make cell membranes more pliable, which, in turn, makes it easier to pass nutrients and waste products in and out of the cells.

In the end, here's something that really needs to be driven home.  Starters a little like nuclear weapons in that close enough gets the job done.  Cell population growth is exponential, not linear.   Hence, the difference between 200 billion cells and 400 billions cell is roughly one reproduction period, and the difference between 200 billion cells and 800 billion cells is roughly two replication periods.  Dissolved O2, the amount of carbon (extract), and volume of the liquid medium all play a role in replication.   The best thing that we can do as brewers is to ensure that the cells that we pitch are healthy because healthy cells reproduce.   The other thing that need to do is to ensure that we aerate our wort because healthy cells can become unhealthy cells without adequate aeration.
Title: Re: Right RPM for stir plate?
Post by: Stevie on January 14, 2015, 06:12:07 PM
So without using a microscope, you just make a starter of N to get N x 100B cells?
Title: Re: Right RPM for stir plate?
Post by: narcout on January 14, 2015, 06:52:22 PM
Starters a little like nuclear weapons in that close enough gets the job done.

Agree.

Cell population growth is exponential, not linear.   Hence, the difference between 200 billion cells and 400 billions cell is roughly one reproduction period, and the difference between 200 billion cells and 800 billion cells is roughly two replication periods.  Dissolved O2, the amount of carbon (extract), and volume of the liquid medium all play a role in replication.

I take your point, but as you note (and as is shown in Yeast) there are factors which affect the number of reproduction periods that will be obtained.  Also, as I think you've referenced before, the amount of cell reproduction has flavor implications.

Anyway, I'm making a starter tomorrow night for a dunkel I will brew on Friday night and pitch Saturday morning.  I'm going to attempt to cold crash the starter at the end of the exponential phase rather than waiting for it to ferment out (if I make it home from work in time Friday afternoon).  I'll be curious to see if the supernatant, as you call it, tastes any different than usual.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 14, 2015, 06:58:31 PM
non scientific but i can say that when i made a lager starter less than 1-gal on stir plate fully fermented, i had off flavors to deal with that didn't always clean up with d-rest and lagering. when i made a 3.8-4L starter on a stir plate and fully fermented, my lagers were extremely clean and ready to drink at the 3-4 weeks mark.

Conclusion: right amount of healthy yeast gets the job done with good results...enough science for me without really knowing cell counts...just targets
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 14, 2015, 07:26:30 PM
non scientific but i can say that when i made a lager starter less than 1-gal on stir plate fully fermented, i had off flavors to deal with that didn't always clean up with d-rest and lagering. when i made a 3.8-4L starter on a stir plate and fully fermented, my lagers were extremely clean and ready to drink at the 3-4 weeks mark.

Conclusion: right amount of healthy yeast gets the job done with good results...enough science for me without really knowing cell counts...just targets
How did you do a 3.8-4L starter on a stir plate?  Do I need a heavy duty stir plate?  What vessel did you use?  Can I use a 1 gal. glass jar with a flat bottom?
In the less-than-1 gal. and also the 4L did you decant the beer and pitch the slurry or did you pitch the whole starter?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 14, 2015, 07:41:33 PM
non scientific but i can say that when i made a lager starter less than 1-gal on stir plate fully fermented, i had off flavors to deal with that didn't always clean up with d-rest and lagering. when i made a 3.8-4L starter on a stir plate and fully fermented, my lagers were extremely clean and ready to drink at the 3-4 weeks mark.

Something does not sound right.  I have fermented normal gravity 5.5-gallon batches with as little as a 1L starter without off-flavors.   What kinds of off-flavors do you have?  How much head space did you have in the starter vessel?  Initial dissolved O2 level is more critical than continuous stirring.  All continuous stirring does is keep the cells from dropping out of suspension prematurely.

Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 14, 2015, 07:45:36 PM

non scientific but i can say that when i made a lager starter less than 1-gal on stir plate fully fermented, i had off flavors to deal with that didn't always clean up with d-rest and lagering. when i made a 3.8-4L starter on a stir plate and fully fermented, my lagers were extremely clean and ready to drink at the 3-4 weeks mark.

Conclusion: right amount of healthy yeast gets the job done with good results...enough science for me without really knowing cell counts...just targets
How did you do a 3.8-4L starter on a stir plate?  Do I need a heavy duty stir plate?  What vessel did you use?  Can I use a 1 gal. glass jar with a flat bottom?
In the less-than-1 gal. and also the 4L did you decant the beer and pitch the slurry or did you pitch the whole starter?
I have larger stir plate and 5L flask. I do decant -always.  You can use whatever works on your stir plate.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 14, 2015, 07:47:34 PM

non scientific but i can say that when i made a lager starter less than 1-gal on stir plate fully fermented, i had off flavors to deal with that didn't always clean up with d-rest and lagering. when i made a 3.8-4L starter on a stir plate and fully fermented, my lagers were extremely clean and ready to drink at the 3-4 weeks mark.

Something does not sound right.  I have fermented normal gravity 5.5-gallon batches with as little as a 1L starter without off-flavors.   What kinds of off-flavors do you have?  How much head space did you have in the starter vessel?  Initial dissolved O2 level is more critical than continuous stirring.  All continuous stirring does is keep the cells from dropping out of suspension prematurely.
Talking lagers here. 1L starter wouldn't cut it IME. Also talking about negative aspects of unhealthy, stressed yeast and their contributions to the beer.
Title: Q
Post by: S. cerevisiae on January 14, 2015, 08:40:21 PM
Talking lagers here. 1L starter wouldn't cut it IME. Also talking about negative aspects of unhealthy, stressed yeast and their contributions to the beer.

Yes, a 1L starter will cut it if grown correctly and pitched at the correct time.

In my humble opinion, stir plates are the brewing snake oil of the twenty-first century.  They were introduced to brewing by scientists involved in suspension cell culture (primarily cancer research).  Clumping is a problem in suspension cell culture.  The purpose of using a stir plate in cell culture is to prevent clumping.  It does not aerate as home brewers have been led to believe, especially when the media in the stirred vessel consumes more than 1/3rd of the internal volume.

Here's a test that you can run if you do not believe me.  Prepare 1L of 1.040 (10%) wort like you would when making a stirred starter (use extra light DME).  Chill and pour the media into a sanitized 1-gallon jug using a sanitized funnel if necessary (alternatively, you can pour the media into a sanitized 1-gallon jug hot and let it cool, but you will need to warm the jug first to prevent stress fractures).  After the media has been cooled and transferred to the jug, remove the cap from the White Labs vial, take a cotton swab that has been soaked with 91% isopropyl alcohol, and lightly wipe the surface of the lip of the vial over which the culture will be poured (try to avoid having alcohol run down the sides of the vial).  After waiting about thirty seconds, take a lighter and quickly pass the pouring lip through the flame (alternatively, move the lighter instead of the vial).  You will need to make quick passes in order to avoid melting the vial.   Now, quickly pour the yeast culture into the jug after flaming the lip of the vial, and screw on a sanitized plastic 1-gallon jug replacement cap (most home brewing supply store sell these caps).  Do not use a paper lined cap.  After the cap has been screwed on, shake the jug until the media is almost all foam.   All you need to do from this point forward is loosen the cap after the foam settles down and wait until high krausen, which should occur within 12 to 18 hours (often sooner).   Pitch the entire contents of the jug after high krausen has been reached using the same basic aseptic transfer technique that was performed with the White Labs vial (i.e., wipe and flame the lip of the jug before pitching its contents).  You will need to ensure that your wort is well aerated.

I guarantee that a 1L starter grown this way will fully attenuate a 5-gallon batch of lager at lager fermentation temperatures without producing off-flavors (a 2L starter will reduce O2 requirements and the exponential phase slightly).  In fact, I guarantee that is works as well, if not better than a much larger volume starter that is grown on a stir plate the way that most home brewers make starters on a stir plate.  Unlike a stirred starter, a shaken starter that is pitched at high krausen does not taste, nor does it smell foul; hence, there is no need to decant other than the desire to avoid diluting one's wort.  The reason why a stirred starter smells so bad is that stirring fast enough to get any kind of gas exchange stresses the heck out of the cells.  Yeast produced odors and off-flavors are almost always a sign of stress.
Title: Re: Right RPM for stir plate?
Post by: denny on January 14, 2015, 09:56:17 PM
All I can tell ya is that I've tried almost exactly what's described above and I get much better and faster results with a stir plate.  Thank you for the theory, but I'm pragmatic.  I test different theories and do what works best for me in the real world.  As do you and all the rest of us.  All the theory in the world means nothing to me if my own practices produce better results.
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 14, 2015, 10:10:34 PM
" Unlike a stirred starter, a shaken starter that is pitched at high krausen does not taste, nor does it smell foul; hence, there is no need to decant other than the desire to avoid diluting one's wort.  The reason why a stirred starter smells so bad is that stirring fast enough to get any kind of gas exchange stresses the heck out of the cells.  Yeast produced odors and off-flavors are almost always a sign of stress."

S. cerevisiae,
You should go by James Bond 007.  Shaken not stirred, you wouldn't want to bruise the yeast. :-)

But what you said makes sense and I'll give it a try, though I may go to a 2L starter for lager.  Do you (or anyone) see a problem with filling the headspace in the starter vessel with welding O2 before the initial shake? 
Oh, and why the extra light DME?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 14, 2015, 10:26:26 PM
All I can tell ya is that I've tried almost exactly what's described above and I get much better and faster results with a stir plate.  Thank you for the theory, but I'm pragmatic.  I test different theories and do what works best for me in the real world.  As do you and all the rest of us.  All the theory in the world means nothing to me if my own practices produce better results.

The procedure that I proposed is not theory.  It's a practice that has stood the test of time.  If the procedure does not work for you, then you are performing a step differently because the results have been repeated by many people.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 14, 2015, 10:34:29 PM
Oh, and why the extra light DME?

Extra light DME usually contains a higher percentage of sugars that can be reduced to glucose by yeast cells than the darker DMEs.
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 15, 2015, 02:00:11 AM
Oh, and why the extra light DME?

Extra light DME usually contains a higher percentage of sugars that can be reduced to glucose by yeast cells than the darker DMEs.
OK, thanks, I'll try that.
Any thoughts on the welding O2?  Increasing the percentage of O2 in the vessel headspace should help to get oxygen into the starter when shaken.  O2 is 20% of air so 1L of starter in a 1 gal. vessel gives 0.6 (approx.) volumes of O2 per volume of starter.  Increasing the O2 percentage in the headspace to 60% gives the same ratio of O2 volumes to starter volumes in 2L in a 1 gal. vessel.
Title: Re: Right RPM for stir plate?
Post by: Joe Sr. on January 15, 2015, 02:04:27 AM
Oh, and why the extra light DME?

Extra light DME usually contains a higher percentage of sugars that can be reduced to glucose by yeast cells than the darker DMEs.
OK, thanks, I'll try that.
Any thoughts on the welding O2?  Increasing the percentage of O2 in the vessel headspace should help to get oxygen into the starter when shaken.  O2 is 20% of air so 1L of starter in a 1 gal. vessel gives 0.6 (approx.) volumes of O2 per volume of starter.  Increasing the O2 percentage in the headspace to 60% gives the same ratio of O2 volumes to starter volumes in 2L in a 1 gal. vessel.

Don't overthink it.  My takeaway from this thread is that simple processes are just fine.

I will choose to stick with my stir plates.  Shake if you choose.  Pumping O2 into the headspace seems unnecessary.
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 15, 2015, 02:17:14 AM
"Don't overthink it.  My takeaway from this thread is that simple processes are just fine."

Overthinking is fun.  Under-thinking is fun too...if you've had enough beer!

Hmm...I may have found a sig line.
Title: Re: Right RPM for stir plate?
Post by: narcout on January 15, 2015, 04:59:58 PM
What's the right RPM for stir plate?

I turn mine up just enough so that the wort is rotating, which sometimes results in a small dimple on the surface.  To my eyes, this is less agitation than occurs in the fermentor during peak fermentation.

I used to not oxygenate my starters, I do now

I've started doing this as well.  How long of a blast of O2 are you hitting them with?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 15, 2015, 09:20:48 PM
Any thoughts on the welding O2?  Increasing the percentage of O2 in the vessel headspace should help to get oxygen into the starter when shaken.  O2 is 20% of air so 1L of starter in a 1 gal. vessel gives 0.6 (approx.) volumes of O2 per volume of starter.  Increasing the O2 percentage in the headspace to 60% gives the same ratio of O2 volumes to starter volumes in 2L in a 1 gal. vessel.

If you want to inject O2, you should purchase 2 micron sintered stainless stone.   If you aerate the wort using a sterilized stone, you will not need to shake or have more head space than is necessary to keep the foam from coming out of the starter vessel.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 15, 2015, 10:14:01 PM
I was reading publications on suspension cell culturing last night, and they pretty much concurred with what I have written in this thread.  A stir speed that is fast enough to aerate the medium when using an Erlenmeyer flask and a magnetic stir bar results in shear force being placed on the cells.  In effect, a stir speed greater than 40 RPM can do more harm than good.   When using an Erlenmeyer flask and a magnetic stir bar, 40 RPM is not going to aerate wort without outside assistance.  We went to pitch happy, healthy yeast cells, not stressed out cells.

Now, those who insist on using a stir plate without forced aeration should seriously look into purchasing what is known as a "spinner flask" (price sensitive brewers should expect to experience major sticker shock if purchasing new).  There are two basic types of spinner flask.  One of the basic types has a suspended stir bar.  This type of spinner flask only agitates a culture, which does not make it much better than an Erlenmeyer flask with a magnetic stir bar.  The other basic type sports a vertical impeller.  That's the type that one wants when propagating yeast.  If possible, one wants to purchase a spinner flask where the impeller is tall enough that it sticks out of the wort, which will ensure adequate gas exchange at cell-friendly stir speeds.

Bar-Type Spinner Flask

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/bar-type-spinner-flask_zps63ff0e0d.jpg)


Short Impeller-Type Spinner Flask

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/impeller-type-spinner-flask_zps08d52b22.jpg)

Tall Impeller-Type Spinner Flask

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/tall-impeller-type-spinner-flask_zpsda803a1d.jpg)




Title: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 15, 2015, 10:50:08 PM
cool thought. however i'm sure i'm not the only one who will say the following: many award winning, top quality, great tasting home brew beers have been made and will continue to be made with starters and stir plates...many of them i'd rate better than several commercial beers.  hows that song go..."must be doing something right".

at the end of the day, if what i make or what i drink tastes and smells like what I consider to be a good, great, or exceptional beer.... then in that, I trust.
Title: Re: Right RPM for stir plate?
Post by: jlevensailor on January 16, 2015, 01:06:23 AM
Correct me if i'm wrong
Yeast has 3 phases:
1. anaerobic - reproduce
2. aerobic - eat
3. cold - sleep

With this knowledge, it's better to keep a yeast starter barely covered to stop contamination, but allow breathing.
I've seen a lot of people use airlocks on their flasks

RIGHT?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 16, 2015, 01:13:17 AM
More award winning beers have been made without the aid of a stir plate than with one.   The wide use of a stir plate when making a starter is a relatively new thing.

I am not asking you to accept my method.  I am asking you to question your method because one stops growing as a brewer the moment that one stops questioning one's methods.  How many starters did you make before purchasing a stir plate?   How many side-by-side stir plate/non-stir plate tests have you conducted since purchasing a stir plate?   How do you personally know that a stir plate produces a healthier starter?

Like many, I initially accepted the claims made by those who were using stir plates to make yeast starters.  However, I had well over a decade of experience propagating almost every culture that I used from slant before starting to use a stir plate.  My results did not correlate with the claims being made by others.  Not only that, the claims being made by others did not align with science, which is why I spent six months making side-by-side comparisons before I came to the conclusion that some well meaning home brewer took the use of a stir plate in suspension cell culturing and blew it up into a must have when making a yeast starter.   

The reason why stir plates are used in suspension cell culturing is because it can be difficult to grow some cell lines because they want to clump together, which results in lower viable cell densities.  Continuous agitation helps to keep the cells in suspension.  The only place cell attachment is a problem when making a starter is when propagating extremely flocculent yeast strains.

Stir plates are not thing only half-baked science that has been preached as gospel to home brewers.  The same thing happened with yeast rinsing.  Some well-meaning home brewer took research that was performed by the ATCC back in the late eighties/early nineties involving the storage of small amounts of yeast cells under sterile water for extended periods of time and blew it up into the greatest yeast cropping and storage method since sliced bread.  The sad part is that the people promoting each process failed to understand the context in which the basic science was developed.  In the case of the ATCC research, the cultures were separated from all traces of nutrient via the use of a centrifuge before being stored under sterile water.  Boiled water cannot be assumed to be sterile because boiling does not kill spores.  Water has to be autoclaved to render it sterile, but the need to remove all traces of nutrient and use of truly sterile water fell by the wayside as the practice of rinsing yeast with and storing it under boiled water permeated the community.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 16, 2015, 01:24:25 AM
We don't have to agree- that's the beauty of brewing. I'm very open to change- if it means it changes my finished product in a perceivable way....done it many times already and imagine it won't stop. But I can say that there's more than one way to make great beer- i truly believe that the more I brew and the more I see how different practices can produce the same results- great beer.
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 16, 2015, 02:49:32 AM
Any thoughts on the welding O2?  Increasing the percentage of O2 in the vessel headspace should help to get oxygen into the starter when shaken.  O2 is 20% of air so 1L of starter in a 1 gal. vessel gives 0.6 (approx.) volumes of O2 per volume of starter.  Increasing the O2 percentage in the headspace to 60% gives the same ratio of O2 volumes to starter volumes in 2L in a 1 gal. vessel.

If you want to inject O2, you should purchase 2 micron sintered stainless stone.   If you aerate the wort using a sterilized stone, you will not need to shake or have more head space than is necessary to keep the foam from coming out of the starter vessel.
Thanks S. cerv,
Much appreciate your (and everyone's) input.  I may get a 2 mc SS stone but your basic "shake it" approach appeals to my KISS side.
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 16, 2015, 02:51:15 AM
What's the right RPM for stir plate?

I turn mine up just enough so that the wort is rotating, which sometimes results in a small dimple on the surface.  To my eyes, this is less agitation than occurs in the fermentor during peak fermentation.

I used to not oxygenate my starters, I do now

I've started doing this as well.  How long of a blast of O2 are you hitting them with?
For a 2L starter, enough to give it a decent layer of froth on top but not over flowing the flask. Maybe 10 seconds
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 16, 2015, 02:57:12 AM
"spinner flask" (price sensitive brewers should expect to experience major sticker shock if purchasing new). 
Ha!  Now there's some hi quality internet snarc right there.  I love it!  Let's be honest, we all enjoy it.  And no, there's no way I'm EVEN going to look up the price of one of those "spinner" puppies.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 16, 2015, 03:13:31 AM
Correct me if i'm wrong
Yeast has 3 phases:
1. anaerobic - reproduce
2. aerobic - eat
3. cold – sleep


No, yeast cells normally go through three major phases.  The first phase is the called the lag phase.  During the lag phase, the yeast cells adapt to their new environment and prepare to bud.  The next phase is called the log or exponential phase.  During the exponential phase, yeast cells are budding (multiplying) like crazy.  The final phase is called the stationary phase.  Depending on whose work one reads, each of the major phases has one or more sub-phases.

The thing that confuses most people is that yeast cells have two separate metabolic pathways. The first metabolic pathway is called the respirative (aerobic) metabolic pathway.  The respirative metabolic pathway is extremely efficient. It basically converts sugar to water and carbon dioxide gas.  The second metabolic pathway is called the fermentative (anaerobic) metabolic pathway. It is the pathway through which sugar is converted primarily to ethanol (which is a carbon-based compound) and carbon dioxide gas.  The fermentative metabolic pathway is not anywhere near as efficient as the respirative metabolic pathway.   

Many older home brewing texts erroneously refer to the growth phase as respiration.   Brewing yeast cells do not respire in beer wort due to something known as the Crabtree Effect.  The Crabtree Effect states that yeast cells will favor fermentation over respiration when subjected to dissolved glucose levels above the Crabtree threshold, and they will do so even in the presence of dissolved oxygen (O2).  The Crabtree threshold is around 0.3% weight/volume (w/v). 

To put things into context, the extract from the average mash contains roughly 14% glucose, which means that wort with a specific gravity above 1.008 contains a glucose level above the Crabtree threshold.

Here's the math:

A 1.008 solution is a 2% sugar weight/weight (w/w) solution, which is the same thing as w/v when dealing with a solute dissolved into water because 1ml of water weighs one gram.  Of that 2%, only 14% is glucose; hence, 0.02 x 0.14 = 0.0028, or 0.28% glucose w/v, which is below the Crabtree threshold.

As all beer and batch yeast propagation worts have specific gravities above 1.008, yeast biomass growth in brewing is fermentative.  Now, the metabolic pathways in yeast cells are a little on the leaky side.  What yeast cells do while there is still O2 in solution is shunt a small percentage of the glucose being consumed to the respirative metabolic pathway for the synthesization of ergosterol and unsaturated fatty acids (UFA).   These compounds make cell membranes more pliable, which, in turn, make passage of nutrients and waste products in and out of the cells easier.

Quote
With this knowledge, it's better to keep a yeast starter barely covered to stop contamination, but allow breathing.
I've seen a lot of people use airlocks on their flasks

RIGHT?

I am sorry to inform you, but the no airlock argument is also for the most part home brewer pseudo-science.   CO2 is heavier than air.  Plus, the culture is under positive pressure; hence, little to no O2 makes it into solution from the atmosphere after CO2 production begins, especially in an Erlenmeyer flask.  The only way to ensure that a culture receives a continuous supply of O2 is to use forced aeration throughout propagation. 

With that said, there is a way to propagate yeast respiratively, but it requires a hi-tech piece of equipment known as a bioreactor.  This type of propagation differs from how brewers propagate yeast.  Brewers use batch propagation.  Respirative propagation is a continuous process in which nutrient and O2 are continuously added to the medium while yeast cells are continuously drawn off.   A bioreactor makes this process possible because it can hold the dissolved glucose level in a steady state below the Crabtree threshold.  Lallemand and Lesaffre (the parent company of Fermentis) use this type of propagation to produce dry yeast cultures.  Respirative growth is more efficient than fermentative growth; hence, more yeast cells can be produced using the same amount of carbon (sugar is basically carbon bound to water).  Respirative growth also has the added advantage of continuous ergosterol and UFA production; hence, the yeast cells that are produced via the process do not need to undergo ergosterol and UFA replenishment after being pitched.  As mentioned above, yeast cells use the O2 that is solution at the beginning of fermentation to synthesize ergosterol and UFAs via the respirative metabolic pathway.  Pitching fully-charged yeast cells basically eliminates the need to aerate one’s wort.

For anyone who is interested in learning more about Lallemand’s yeast propagation process.  Here’s a link a to short paper that describes how they propagate baker’s yeast in layman's terms.   Baker’s yeast and brewer’s yeast are the same yeast species; namely, Saccharomyces cerevisiae (S. cerevisiae).  The strains only differ in the application at which they excel.

http://www.lallemand.com/BakerYeastNA/eng/PDFs/LBU%20PDF%20FILES/1_9YPROD.PDF

“Growing via respiration is important because it is about eighteen times as efficient as fermentation at converting sugar into yeast. The tendency of yeast to grow via respiration when large amounts of oxygen are present is known as the Pasteur effect. The tendency of yeast to grow via fermentation when high levels of sugar are present is known as the Crabtree effect.  The combination of Pasteur and Crabtree effects in Saccharomyces cerevisiae is the reason commercial bakers yeast fermentations use high aeration and incremental feeding to maintain high oxygen and low sugar levels throughout the process.”

Title: Re: Right RPM for stir plate?
Post by: narcout on January 16, 2015, 03:08:33 PM
For a 2L starter, enough to give it a decent layer of froth on top but not over flowing the flask. Maybe 10 seconds

10 seconds is about what I've been using as well.  Have you noticed much of a difference?  I don't know that I can say it definitively, but it seems like my oxygenated starters take off more quickly.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 16, 2015, 03:20:43 PM
For a 2L starter, enough to give it a decent layer of froth on top but not over flowing the flask. Maybe 10 seconds

10 seconds is about what I've been using as well.  Have you noticed much of a difference?  I don't know that I can say it definitively, but it seems like my oxygenated starters take off more quickly.
i give a shot of o2 also. if in fact very little o2 is added during stir plate activity, makes sense to me to add o2 to starters just like I do making full batch.
Title: Re: Right RPM for stir plate?
Post by: Stevie on January 16, 2015, 03:46:01 PM
My whole issue is that both whitelabs and wyeast promote the use of stir plates. If they were voodoo, I think wyeast and whitelabs would call it out allowing them to sell more yeast.
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 16, 2015, 04:05:02 PM
My whole issue is that both whitelabs and wyeast promote the use of stir plates. If they were voodoo, I think wyeast and whitelabs would call it out allowing them to sell more yeast.
I think stirplates are great. The point is that they dont add enough O2, probably.
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 16, 2015, 04:11:28 PM
For a 2L starter, enough to give it a decent layer of froth on top but not over flowing the flask. Maybe 10 seconds

10 seconds is about what I've been using as well.  Have you noticed much of a difference?  I don't know that I can say it definitively, but it seems like my oxygenated starters take off more quickly.
In my change to adding O2, I also made up a fresh couple of cases of starter wort, and its half gallon pressure canned 1.030 extra light DME and each jar got canned with wyeast nutrients inside.

So for me two changes. O2 and nutrient. My starters are clearly bigger and healthier.
Title: Re: Right RPM for stir plate?
Post by: denny on January 16, 2015, 04:48:15 PM
cool thought. however i'm sure i'm not the only one who will say the following: many award winning, top quality, great tasting home brew beers have been made and will continue to be made with starters and stir plates...many of them i'd rate better than several commercial beers.  hows that song go..."must be doing something right".

at the end of the day, if what i make or what i drink tastes and smells like what I consider to be a good, great, or exceptional beer.... then in that, I trust.

THIS^^^^  I'll change my methods when I don't get great results with my current method.
Title: Re: Right RPM for stir plate?
Post by: JT on January 16, 2015, 06:00:56 PM
cool thought. however i'm sure i'm not the only one who will say the following: many award winning, top quality, great tasting home brew beers have been made and will continue to be made with starters and stir plates...many of them i'd rate better than several commercial beers.  hows that song go..."must be doing something right".

at the end of the day, if what i make or what i drink tastes and smells like what I consider to be a good, great, or exceptional beer.... then in that, I trust.

THIS^^^^  I'll change my methods when I don't get great results with my current method.
Depends.  Even if I'm getting good results, I'll try something new in a heartbeat just to see if I like the results even better - as long as it doesn't require a bunch of extra effort or cash. 
Title: Re: Right RPM for stir plate?
Post by: denny on January 16, 2015, 06:48:27 PM
Depends.  Even if I'm getting good results, I'll try something new in a heartbeat just to see if I like the results even better - as long as it doesn't require a bunch of extra effort or cash.

Me, too, which is how I arrived at my current method.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 16, 2015, 07:06:05 PM
I'm just happy the documented trial and errors of the  Brewers that have been brewing 20-30+ years are easily accessible on the web- made life learning to brew much easier. Imagine when you needed some guidance or an answer , and no web, forums, Google. 
Title: Re: Right RPM for stir plate?
Post by: JT on January 16, 2015, 07:10:45 PM
I'm just happy the documented trial and errors of the  Brewers that have been brewing 20-30+ years are easily accessible on the web- made life learning to brew much easier. Imagine when you needed some guidance or an answer , and no web, forums, Google.
I was just thinking this the other day!  Things we take for granted...
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 16, 2015, 07:12:47 PM
Imagine when you needed some guidance or an answer , and no web, forums, Google. 

I resemble that  :D     If nothing else, I learned the value of the split batch - it was a good way to get extra info quicker. That and taking a hell of a lot of notes !
Title: Re: Right RPM for stir plate?
Post by: archstanton on January 16, 2015, 07:45:13 PM
Imagine when you needed some guidance or an answer , and no web, forums, Google. 

I resemble that  :D     If nothing else, I learned the value of the split batch - it was a good way to get extra info quicker. That and taking a hell of a lot of notes !

No software either. That's how I learned to brew, a few books and learned experience. I find the internet to be a great place to learn tricks and develop gadgets and streamline processes.  I do feel that something learned through personal experience is much harder to let go of than something learned form a book. A difference between knowledge and education maybe???
Title: Re: Right RPM for stir plate?
Post by: mabrungard on January 16, 2015, 08:42:14 PM
Wow! What a great thread that is hidden under this crappy title. I had not considered looking at it until now and am glad I did.

First to the OP's question, I agree that the proper stir plate rpm is that which keeps the yeast in suspension. There is no need or advantage to high rpm and a frothy vortex.

Mark, you have incredible knowledge shared here. I agree that a stir plate is not ideal, but I don't think that its terrible. One thing that is true, is that a stir plate alone is not sufficient to keep a starter aerobic when using typical narrow-ended vessels. There is little chance that there will be enough exchange with the normal atmosphere to transfer enough oxygen. That is why I flood the headspace of my starter flask with ambient air that is filtered through a 0.45 micron filter. That way, I know there IS enough oxygen present in the headspace to transfer into the gently-stirred wort below. Mark, is your problem with stir plates the fact that they aren't keeping the wort aerobic...or some other reason?

According to (Verstrepen KJ, et al.Yeast flocculation: What Brewers Should Know.” Applied Microbiology and Biotechnology, Vol 61, pp 197-205, 2003.), flocculation is generally inhibited during active fermentation by the presence of mannose, maltose, glucose, and sucrose in the wort. So that means that if the yeast tend to quickly settle when you stop stirring, the wort is exhausted. With the information in this thread from Mark, I now know that I should get that starter into the fridge to settle for decanting. I have probably been continuing the stirring for too long. I'll revise my procedures.

Mark, I read your contention that temperature control is not that important. But I'm concerned that your example yeast species may not be a true case in point. While it apparently works for that relatively clean fermenting yeast, I'm curious if that result can be applied across the entire yeast spectrum? I anticipate that it can't. Can you expand on that?
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 16, 2015, 10:31:07 PM
I remember him delineating between ? positive and ? negative strains, and whatever negative would be fine but the ones that crank out (phenols maybe) probably ought to be temp controlled. But here's the thing. I have temp control, im going to use it, regardless of what the people with letters after their names say. I know for fact that I make my beere better with my temp control. Your mileage may or may not vary
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 16, 2015, 11:10:39 PM
My whole issue is that both whitelabs and wyeast promote the use of stir plates. If they were voodoo, I think wyeast and whitelabs would call it out allowing them to sell more yeast.

It's not that stir plates are voodoo science.  It's that the way that stir plates are promoted in home brewing is voodoo science much in the same way that the process of rinsing yeast with and storing it under boiled tap water is voodoo science.   When used with an Erlenmeyer flask and a stir bar, a stir plate does one thing well; namely, keep cells in suspension.  Most of the popular brewing cultures remain in suspension without the aid of a stir plate during propagation.  If these strains did not remain in suspension during propagation, they would have been discarded years ago because production breweries cannot afford to use strains or mixed cultures that are prone to premature flocculation.
Title: Re: Right RPM for stir plate?
Post by: Stevie on January 16, 2015, 11:38:36 PM
So why would two reputable yeast labs promote them? Obviously, you have done stacks of research, but they are considered industry experts with a few phd's in their stables.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 16, 2015, 11:48:09 PM
My whole issue is that both whitelabs and wyeast promote the use of stir plates. If they were voodoo, I think wyeast and whitelabs would call it out allowing them to sell more yeast.

It's not that stir plates are voodoo science.  It's that the way that stir plates are promoted in home brewing is voodoo science much in the same way that the process of rinsing yeast with and storing it under boiled tap water is voodoo science.   When used with an Erlenmeyer flask and a stir bar, a stir plate does one thing well; namely, keep cells in suspension.  Most of the popular brewing cultures remain in suspension without the aid of a stir plate during propagation.  If these strains did not remain in suspension during propagation, they would have been discarded years ago because production breweries cannot afford to use strains or mixed cultures that are prone to premature flocculation.

question Mark: are you saying yeast cell counts/growth for non stir plate starter is the same as stir plate starter-regardless of how long you leave it on stir plate?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 17, 2015, 12:54:30 AM
Mark, is your problem with stir plates the fact that they aren't keeping the wort aerobic...or some other reason?

My problem with stir plates is that they, like yeast rinsing, have been sold to the home brewing community based on faulty information.  A stir plate is a poor investment when used with an Erlenmeyer flask and a stir bar.  This setup has been sold to home brewers as a self-aerating, "set it and forget it" way to propagate yeast.  The craziest thing is that brewers who arrived on the scene after the introduction of stir plates have been taught that starter media is always too foul to pitch.  Foul smelling media is a sign that the yeast cells in one's starter are stressed.

The most critical thing that a new brewer needs to learn when making a starter is that sanitation is even more critical when propagating yeast than it is when making beer.   He/she also needs to learn that the purpose of a starter is to increase yeast biomass, not produce ethanol; hence, nothing is gained by letting a starter run past the exponential phase.  Most importantly of all, aeration is critical to restoring the health of yeast cells that have been in the stationary phase for a long period of time, and that O2 has to be in solution when or shortly after the culture has been pitched.

Quote
Mark, I read your contention that temperature control is not that important. But I'm concerned that your example yeast species may not be a true case in point. While it apparently works for that relatively clean fermenting yeast, I'm curious if that result can be applied across the entire yeast spectrum? I anticipate that it can't. Can you expand on that?

My post was meant to bring attention to the fact that temperature-controlled fermentation chambers are one of the first things that are pushed onto new brewers when they inquire about process improvement, not that there is never a need for temperature control.  More often than not, quality control problems have little to do with whether or not not a brewer is using tight or stepped temperature regulation during fermentation, especially when using a yeast strain that is as forgiving as BRY 96, which is the most popular yeast strain in home and craft brewing by a sizable margin.  The number one thing that will hold brewers back from producing quality beer is less than optimal sanitation. 

Prospective new brewers that discover that I brew often ask me if they can learn how to make quality beer expecting that I will ask them if they know how to cook.  Most are completely floored when I tell them that making quality beer has more to do with how well one can clean than how well one can cook.  Wort tastes nothing like beer because brewers do not make beer, yeast cells make beer; hence, our actions as brewers should be directed at keeping invaders out of the process and treating the yeast culture that we pitch as the most important ingredient.  How we accomplish that feat is through good brewery hygiene, careful post-chilling wort handling, and ensuring that our cultures are biologically clean and healthy.  A temperature-controlled fermentation chamber helps a brewer improve none of the areas listed above.  However, what it will do is mask poor yeast management as well as poor post-chilling wort handling and sanitation practices by suppressing less cold tolerant microflora, which are more often than not are the resident microflora found in one's home.   
Title: Re: Right RPM for stir plate?
Post by: hophead636 on January 17, 2015, 01:07:37 AM

Mark, is your problem with stir plates the fact that they aren't keeping the wort aerobic...or some other reason?

My problem with stir plates is that they, like yeast rinsing, have been sold to the home brewing community based on faulty information.  A stir plate is a poor investment when used with an Erlenmeyer flask and a stir bar.  This setup has been sold to home brewers as a self-aerating, "set it and forget it" way to propagate yeast.  The craziest thing is that brewers who arrived on the scene after the introduction of stir plates have been taught that starter media is always too foul to pitch.  Foul smelling media is a sign that the yeast cells in one's starter are stressed.

The most critical thing that a new brewer needs to learn when making a starter is that sanitation is even more critical when propagating yeast than it is when making beer.   He/she also needs to learn that the purpose of a starter is to increase yeast biomass, not produce ethanol; hence, nothing is gained by letting a starter run past the exponential phase.  Most importantly of all, aeration is critical to restoring the health of yeast cells that have been in the stationary phase for a long period of time, and that O2 has to be in solution when or shortly after the culture has been pitched.

Quote
Mark, I read your contention that temperature control is not that important. But I'm concerned that your example yeast species may not be a true case in point. While it apparently works for that relatively clean fermenting yeast, I'm curious if that result can be applied across the entire yeast spectrum? I anticipate that it can't. Can you expand on that?

My post was meant to bring attention to the fact that temperature-controlled fermentation chambers are one of the first things that are pushed onto new brewers when they inquire about process improvement, not that there is never a need for temperature control.  More often than not, quality control problems have little to do with whether or not not a brewer is using tight or stepped temperature regulation during fermentation, especially when using a yeast strain that is as forgiving as BRY 96, which is the most popular yeast strain in home and craft brewing by a sizable margin.  The number one thing that will hold brewers back from producing quality beer is less than optimal sanitation. 

Prospective new brewers that discover that I brew often ask me if they can learn how to make quality beer expecting that I will ask them if they know how to cook.  Most are completely floored when I tell them that making quality beer has more to do with how well one can clean than how well one can cook.  Wort tastes nothing like beer because brewers do not make beer, yeast cells make beer; hence, our actions as brewers should be directed at keeping invaders out of the process and treating the yeast culture that we pitch as the most important ingredient.  How we accomplish that feat is through good brewery hygiene, careful post-chilling wort handling, and ensuring that our cultures are biologically clean and healthy.  A temperature-controlled fermentation chamber helps a brewer improve none of the areas listed above.  However, what it will do is mask poor yeast management as well as poor post-chilling wort handling and sanitation practices by suppressing less cold tolerant microflora, which are more often than not are the resident microflora found in one's home.

Fully agree cleanliness in the brewhouse + sanitation should be your number 1 goal all the time
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 17, 2015, 01:24:11 AM
I can say that if you listen to some pod casts, glance at some yeast calculators or yeast sales sites, it seems that stirl plates just double yeast growth all on their own. That might be the voodoo he's talking about. I'm finding that growth needs O2 and stir plates won't get O2 in there as I was led to believe. I think a shook non stired starter is better than nothing, a shook non stired starter is better than a non shook stired starter. I now, and for now, think my oxygenated stired starter is about as good as I will get. Stir plate does not add oxygen, it keeps cells moving thats it.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 17, 2015, 01:29:55 AM
question Mark: are you saying yeast cell counts/growth for non stir plate starter is the same as stir plate starter-regardless of how long you leave it on stir plate?
[/quote]

What I am saying is that any difference in viable cell count will be insignificant, and the yeast cells in a starter that is stirred fast enough to dissolve oxygen before CO2 production begins will be significantly more stressed than the cells from a starter that is shaken into foam in a vessel that is at least three times the volume of the starter shortly before or after inoculation and left to do its thing. 

As Jim has already discovered by using O2 and a slow stir rate, the medium from a non-stressed culture does not smell or taste foul.  The only reason to decant is to avoid diluting one's wort.  The improved performance that Jim experienced was due to injecting O2 at the start and pitching at high krausen.

Title: Re: Right RPM for stir plate?
Post by: jlevensailor on January 17, 2015, 01:49:46 AM
So after 2 days on stirplate my WLP001 and a weak DME 1.1L wort, I put my flask in the fridge, a day later I see white yeast on the bottom!

Question is, while the yeast looks to be more than what I put in there it isn't more than maybe double it. Should I have a larger amount?


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Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 17, 2015, 02:55:05 AM
So after 2 days on stirplate my WLP001 and a weak DME 1.1L wort, I put my flask in the fridge, a day later I see white yeast on the bottom!

Question is, while the yeast looks to be more than what I put in there it isn't more than maybe double it. Should I have a larger amount?


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One can look to double the volume of yeast cells in a 1.1L starter.   That number of cells will get the job done for most normal gravity ales.   I pitch much less than that amount of yeast when brewing British-style beers (often 1/3rd if I know the strain well).
Title: Re: Right RPM for stir plate?
Post by: jlevensailor on January 17, 2015, 02:58:49 AM
I prefer doing about 7-9ABV DIPAs.  I used beersmith to come up with 1.1L, just wondering if the bottom should have more yeast covered on it..


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Title: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 17, 2015, 03:04:24 AM
question Mark: are you saying yeast cell counts/growth for non stir plate starter is the same as stir plate starter-regardless of how long you leave it on stir plate?


my stir plate has very low speed...doesn't even make  a dimple on low speed-just swirls the wort. thats how I run my starters. there's just a lot of studies out there that will contradict your premise that a stationary starter without any o2 infusion (what most homebrewers do) will  produce the same amount of viable cells as the same on a stir plate. not my studies, just saying.

edit: and FWIW, I admire your passion for yeast...in all seriousness. It's just your practices are not practical for most homebrewers. Most of us can't count cells, we don't have O2 infusion for starters. We are left to either stationary or occasional shaken starters, or stir plates. For many of us, stir plates produce good and excellent results when it comes to the finished product.
Title: Re: Right RPM for stir plate?
Post by: jjflash on January 17, 2015, 03:37:16 AM
So the recommendation is for me to stop using the Erlenmeyer flask / stir bar / stir plate combination.

If I use the Erlenmeyer flask by itself, would it be better to run an air stone continuous, or dose with oxygen?  With a starter with OG 1.035 how much oxygen to add? The standard 1ppm/degree Plato?  Single dose?  Multiple doses?  Let it run 12-18 hours and refrigerate.

I brew big beers only - 1.080 to 1.110+.  I have started to step my starters from 1.035 1 liter first step, refrigerate and decant with yeast to a 1.070 1 liter second step.  I am now testing a new method suggested by Steven Deeds in Brewing Engineering where I use 1 gallon of the final wort for the third step of propagation. Then pitching this yeast into 10-12 gallon batch.   

I am game to try something new, always in search of perfection.
Title: Re: Right RPM for stir plate?
Post by: Philbrew on January 17, 2015, 05:57:11 AM
Wow! What a great thread that is hidden under this crappy title.
Yeah, I started this thread just expecting a simple nuts-and-bolts answer.  Then boom...no KA-BOOM!
This Forum is amazing!  A whole bunch of thoughtful, literate, respectful, fun-loving, BEER-loving folks talking about how to brew beer.  What you folks have done here deserves a very long slow clap!
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 17, 2015, 02:20:47 PM

Wow! What a great thread that is hidden under this crappy title.
Yeah, I started this thread just expecting a simple nuts-and-bolts answer.  Then boom...no KA-BOOM!
This Forum is amazing!  A whole bunch of thoughtful, literate, respectful, fun-loving, BEER-loving folks talking about how to brew beer.  What you folks have done here deserves a very long slow clap!

Yeah you should edit the title so others find it. Something like starter: stir plate or not.


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Title: Re: Right RPM for stir plate?
Post by: mabrungard on January 17, 2015, 03:37:25 PM
"My problem with stir plates is that they, like yeast rinsing, have been sold to the home brewing community based on faulty information.  A stir plate is a poor investment when used with an Erlenmeyer flask and a stir bar.  This setup has been sold to home brewers as a self-aerating, "set it and forget it" way to propagate yeast.  The craziest thing is that brewers who arrived on the scene after the introduction of stir plates have been taught that starter media is always too foul to pitch.  Foul smelling media is a sign that the yeast cells in one's starter are stressed."

...


"My post was meant to bring attention to the fact that temperature-controlled fermentation chambers are one of the first things that are pushed onto new brewers when they inquire about process improvement, not that there is never a need for temperature control.  More often than not, quality control problems have little to do with whether or not not a brewer is using tight or stepped temperature regulation during fermentation, especially when using a yeast strain that is as forgiving as BRY 96, which is the most popular yeast strain in home and craft brewing by a sizable margin.  The number one thing that will hold brewers back from producing quality beer is less than optimal sanitation."


Mark, I see that we agree on the uselessness of trying to propagate a starter without adequate oxygen. Aerobic conditions are REQUIRED for the yeast to synthesize sterols and just putting yeast in a narrow-ended flask is not going to keep the starter aerobic. Nor is a shot of oxygen, once or occasionally. I found that since the need for oxygen in keeping starter wort aerobic is relatively low, the use of air is OK...as long as its filtered adequately to prevent contamination. I understand that filtering at the sub-micron level should be sufficient to remove air-borne contaminants. I also found out the hard way, that using an air-stone for starter aeration is NOT required. Just pumping filtered air into the headspace over the starter wort is adequate. That should keep that headspace at over 19% oxygen content and that should easily transfer to the wort. I have to admit that my apparatus may be better suited for that transfer since I create 1 to 2 liter starters in a 6 liter ehrlenmeyer flask. That leaves a large surface area between the headspace and wort.

Mark, I have to point out your experience with the importance of temperature-control is biased. A basement in a home located in the northern US is actually a nicely temperature-controlled environment that is truly an advantage compared to those that live in a hotter climate and don't have a cool basement. You forgot to take of your blinders on that issue. While I am in the same situation as you...with a nice cool basement...I remember my days in Tallahassee and the dire need for temperature control then. For most brewers, temperature control is a critical step in producing high-quality beer.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 17, 2015, 03:48:42 PM
my stir plate has very low speed...doesn't even make  a dimple on low speed-just swirls the wort. thats how I run my starters. there's just a lot of studies out there that will contradict your premise that a stationary starter without any o2 infusion (what most homebrewers do) will  produce the same amount of viable cells as the same on a stir plate. not my studies, just saying.

I recently stumbled upon a post made by Steven Deeds that blew my mind.   In that post, he made claims that mirrored my findings with respect to stir plates  (I always seem to be the fish that is swimming upstream within the home brewing community when it comes to yeast management).  Steven and I apparently came to the same conclusion in isolation.   After digging deeper into Steven's research, I found that he too discovered the "shake until almost all foam" method that I have been using since 1993.  Most home brewers who make a starter without a stir plate miss this critical step.   Swirling the culture into the media or shaking until a small amount of foam forms will not produce the same results.  One has to seriously shake the culture to produce that much foam, which requires the use of a container with a screw on cap or a sanitized rubber stopper that is held in place with one hand during the shake.  The container should also be at least three times the volume of the starter for best results (preferably four or more times the volume).


Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 17, 2015, 04:40:15 PM
Mark, I have to point out your experience with the importance of temperature-control is biased. A basement in a home located in the northern US is actually a nicely temperature-controlled environment that is truly an advantage compared to those that live in a hotter climate and don't have a cool basement. You forgot to take of your blinders on that issue. While I am in the same situation as you...with a nice cool basement...I remember my days in Tallahassee and the dire need for temperature control then. For most brewers, temperature control is a critical step in producing high-quality beer.

If read all of my posts around where I first surfaced the issue, you will see that I put a disclaimer in for people who live in warm states.

However, that's not how low temperature ale fermentation or temperature ramped fermentation is presented in this forum and others.  It's presented as a requirement for quality ale production.  A temperature-controlled fermentation chamber is one of the first things that I see promoted when a new brewer asks about gear and/or process improvement even though the brewer is fermenting ale.  No one even bothers to ask what the ambient temperature is in the brewer's fermentation room before offering the suggestion.  It's all about using refrigeration for a process that can be performed in the high sixties/low seventies range with excellent results, a temperature range that is easily met for most of the year in below grade basements in states that experience four seasons. The trick is picking the right yeast culture for the task at hand, not tricking the yeast culture into performing the task at hand.  Those who live in warm states have no choice, but to resort to forced attemperation.

The original post was made to highlight the fact that a temperature-controlled fermentation chamber should not be the universal answer to improving fermentation quality, especially when the person making the recommendation has not asked the inquirer if he/she has space in his/her home that remains under 70F.

Over the years,  I have found that most home brewers who have quality issues from a fermentation point of view do not know how to clean and/or sanitize properly.   They also do not recognize how critical it is to be super anal when handling a yeast culture.   It is amazing how much a couple of hours spent teaching a brewer how to clean and sanitize his equipment as well as how to propagate yeast in a way that minimizes the risk of wild microflora contamination can go towards improving batch-to-batch consistency and overall quality. 
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 18, 2015, 12:03:21 AM

Over the years,  I have found that most home brewers who have quality issues from a fermentation point of view do not know how to clean and/or sanitize properly.   They also do not recognize how critical it is to be super anal when handling a yeast culture.   It is amazing how much a couple of hours spent teaching a brewer how to clean and sanitize his equipment as well as how to propagate yeast in a way that minimizes the risk of wild microflora contamination can go towards improving batch-to-batch consistency and overall quality. 

I can see your point to an extent about sanitation. But I don't know, Mark - I've always been pretty 'sanitation OCD' even back before my beers were consistently good. And I remember (pre-temp control) a lot of beers that were perfectly clean but overly estery and fuselly. IIRC these were beers where I pitched from 70-72F for the most part.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 18, 2015, 12:52:45 AM
I can see your point to an extent about sanitation. But I don't know, Mark - I've always been pretty 'sanitation OCD' even back before my beers were consistently good. And I remember (pre-temp control) a lot of beers that were perfectly clean but overly estery and fuselly. IIRC these were beers where I pitched from 70-72F for the most part.

Yes, but if one is pitching at 72F and the ambient room temperature is 72+, one is looking at peak fermentation temperature that could possibly exceed 80F due to the exothermic nature of fermentation.  Additionally, the culture becomes more active as the temperature rises, resulting in even more heat being produced.

I used to pitch ales at 70 to 72F on a fairly regular basis at my previous residence, but my basement was 66F and the carboy sat on a concrete floor, which acted as a heat sink.  My wort temperature would drop to around 66F before fermentation kicked into high gear, and would rarely go above 70F due to the concrete floor sinking heat from the fermentation vessel. 

One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels. 
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 18, 2015, 01:35:14 AM
I can see your point to an extent about sanitation. But I don't know, Mark - I've always been pretty 'sanitation OCD' even back before my beers were consistently good. And I remember (pre-temp control) a lot of beers that were perfectly clean but overly estery and fuselly. IIRC these were beers where I pitched from 70-72F for the most part.

Yes, but if one is pitching at 72F and the ambient room temperature is 72+, one is looking at peak fermentation temperature that could possibly exceed 80F due to the exothermic nature of fermentation.  Additionally, the culture becomes more active as the temperature rises, resulting in even more heat being produced.

I used to pitch ales at 70 to 72F on a fairly regular basis at my previous residence, but my basement was 66F and the carboy sat on a concrete floor, which acted as a heat sink.  My wort temperature would drop to around 66F before fermentation kicked into high gear, and would rarely go above 70F due to the concrete floor sinking heat from the fermentation vessel. 

One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels. 

I should've given more info - at the time I was using glass carboys (before breaking, getting stitches, and going plastic) sitting on a concrete basement floor, too. Even using plastic now, I just like the beers better where I've pitched at 62, fermented at 64F (most strains anyway). Personal preference - I will say that, except for Belgian strains, I do prefer a pretty clean yeast character.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 18, 2015, 06:50:33 AM
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.   

Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 18, 2015, 12:51:40 PM


More award winning beers have been made without the aid of a stir plate than with one.

I'm going to pick on you here. Do you have a reference for this? What is the total count of awards won, and the % of non-stir vs stir? I've not seen competitions require the brewers to list what method of yeast propagation they used, but im new. Did they used to collect that info? Do any of these include awards won prior to the invention of electricity? Because that kind of unfairly stacks the deck in favor of the stirplatephobic hyperbole.
Title: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 18, 2015, 02:10:58 PM
Just poll A few folks Jim- you'll get your answer.

Mark- The point was not to statistically quantify award winning beer. Instead, I'm just contending that it's by no mistake Brewers make beer using starters and stir plates that taste great, win awards, and otherwise meet a standard developed to evaluate quality,

For me , as I said, if it tastes and smells like a great beer ( and that's me comparing to beers I've really Enjoyed) then it is a great beer. I will leave the award judgments to the judges.
Title: Re: Right RPM for stir plate?
Post by: hopfenundmalz on January 18, 2015, 03:09:46 PM
I would like to add that cold crashing at the end of the exponential phase reduces starter lead time from a couple of days to less than 24 hours when pitching a relatively fresh White Labs vial. This reduction in lead time means that a starter can be pitched the evening before one intends to brew, popped into one's refrigerator late morning the following day in preparation for decanting, and pitched late afternoon the following day.

I am going to try this.
Title: Re: Right RPM for stir plate?
Post by: brewday on January 18, 2015, 04:28:18 PM
I would like to add that cold crashing at the end of the exponential phase reduces starter lead time from a couple of days to less than 24 hours when pitching a relatively fresh White Labs vial. This reduction in lead time means that a starter can be pitched the evening before one intends to brew, popped into one's refrigerator late morning the following day in preparation for decanting, and pitched late afternoon the following day.

I am going to try this.

I just gave this a shot - pitching soon....

15 seconds O2 from the stone/red can, stopper w/airlock, no stir plate, no shake, no agitate, 18 hours, cold crash, decant, pitch.

No weird smells or tastes from the starter wort.  I probably could've crashed closer to 12 hours (WY 1968) based on what I saw.  My sense is that I have plenty of healthy yeast to pitch.  I'm hopeful that this leads to me permanently ditching the stir plate.

Awesome thread, thanks for the info Mark!  :D

(http://i725.photobucket.com/albums/ww258/jonnyweave/imagejpg1_zps7c93596a.jpg)
Title: Re: Right RPM for stir plate?
Post by: denny on January 18, 2015, 05:10:03 PM
One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels.

Once again, though, your objection is more theoretical than actual, at least in my experience.  In practice, having used carboys, buckets, and cornies, the difference in thermal conductivity makes little to no difference in actual use.  Your experience may differ from that, but mine is that they work equally well in terms of thermal conductivity.
Title: Re: Right RPM for stir plate?
Post by: denny on January 18, 2015, 05:13:12 PM
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.

And maybe this is the source of the differences...I brew 80% American ales and want the ingredients other than yeast to come through.  But even the Belgian and German styles I brew as the other 20% have benefitted from cooler fermentations.
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 18, 2015, 05:19:48 PM
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.

And maybe this is the source of the differences...I brew 80% American ales and want the ingredients other than yeast to come through.  But even the Belgian and German styles I brew as the other 20% have benefitted from cooler fermentations.

Yeah, that's what I was getting at, too. It's why I like Chico and 1450 for American styles - I like the malt and hops to shine and the yeast to mostly stay out of the way. I don't make as many British styles nowadays for this reason. And like you say, even Belgian beers (to me) are better started cool - I've had banana/phenol bombs from starting Belgian strains too warm. Just personal preference.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 18, 2015, 05:46:49 PM
I'm going to pick on you here. Do you have a reference for this? What is the total count of awards won, and the % of non-stir vs stir? I've not seen competitions require the brewers to list what method of yeast propagation they used, but im new. Did they used to collect that info? Do any of these include awards won prior to the invention of electricity? Because that kind of unfairly stacks the deck in favor of the stirplatephobic hyperbole.

If we are counting NHC awards, then non-stir plate awards dwarf stir plate awards because the universal use of a stir plate is a relatively new thing.  If we are counting local competitions, then the numbers may be more even because of the explosion of local competitions.   

With that said, home brewers made award winning beers for three decades before a stir plate became a "must have."  The data is just not there to prove that stir plates have improved the overall quality of beer.  What has improved the overall quality of home-brewed beer is access to higher quality/fresher ingredients (we used to get product for which there was no professional market), ready-made gear,  and the dissemination of knowledge. 
Title: Re: Right RPM for stir plate?
Post by: archstanton on January 18, 2015, 06:13:10 PM
I brew very few American-style ales.  I like ale to have nice ester profile.   Most of the ale strains that I use are not neutral at normal ale fermentation temperatures.

And maybe this is the source of the differences...I brew 80% American ales and want the ingredients other than yeast to come through.  But even the Belgian and German styles I brew as the other 20% have benefitted from cooler fermentations.

 
Yeah, that's what I was getting at, too. It's why I like Chico and 1450 for American styles - I like the malt and hops to shine and the yeast to mostly stay out of the way. I don't make as many British styles nowadays for this reason. And like you say, even Belgian beers (to me) are better started cool - I've had banana/phenol bombs from starting Belgian strains too warm. Just personal preference.

Brewing my 100th IPA beer right now. I am all about the hops. I have no problem whatsoever fermenting them at 68 and getting completely clean , super hop flavored beer. In fact I have found zero benefit to fermenting at 64 vs 68. In the summer it's 68, in the winter it's 64-66. If I thought there was a perceivable increase in quality, I would ferment them year round at the cooler temperature.

Whenever I look at a gold medal recipe, the fermentation temperature is rarely ever as low as 64, with 66-68 being the norm. Commercial recipes suggest those temps as well- even though most commercial brewers were/are homebrewers, if there were some great discrepancy I think they would make sure and correct it when giving recipes out for homebrewing.

In matters of opinion there is no argument, because you can't account for taste.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 18, 2015, 06:14:34 PM
Once again, though, your objection is more theoretical than actual, at least in my experience.  In practice, having used carboys, buckets, and cornies, the difference in thermal conductivity makes little to no difference in actual use.  Your experience may differ from that, but mine is that they work equally well in terms of thermal conductivity.

My non-attempered fermentations run a degree or two higher in HDPE plastic buckets than they do in glass carboys, so it's real.  If you are using attemperation, then it does not matter what you use as a fermentation vessel.

With that said, my main aversion to HDPE plastic as a fermentation vessel material is biological followed closely by its odor retaining properties.  Regardless of how well one cleans and maintains one's gear, HDPE is a wild microflora magnet.   They only way that I have found to de-funk an HDPE bucket is filling it with caustic, and I prefer to avoid working with that stuff.  While I am not a fan of glass from a safety point of view, it beats HDPE plastic hands down from a microbiological point of view.  One of the upgrades to my brewery that I am planning this year is a move to stainless fermentation vessels.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 18, 2015, 06:22:45 PM
I'm going to pick on you here. Do you have a reference for this? What is the total count of awards won, and the % of non-stir vs stir? I've not seen competitions require the brewers to list what method of yeast propagation they used, but im new. Did they used to collect that info? Do any of these include awards won prior to the invention of electricity? Because that kind of unfairly stacks the deck in favor of the stirplatephobic hyperbole.

If we are counting NHC awards, then non-stir plate awards dwarf stir plate awards because the universal use of a stir plate is a relatively new thing.  If we are counting local competitions, then the numbers may be more even because of the explosion of local competitions.   

With that said, home brewers made award winning beers for three decades before a stir plate became a "must have."  The data is just not there to prove that stir plates have improved the overall quality of beer.  What has improved the overall quality of home-brewed beer is access to higher quality/fresher ingredients (we used to get product for which there was no professional market), ready-made gear,  and the dissemination of knowledge.

like anything new in brewing, its appropriate to create like sample sizes for comparison. while stir plates are relatively new as you say, given the equal time period (say last 5-years for instance) of stir plate use compared to non stir plate use, great beers were produced (whether award winning and medal counting or not).
Title: Re: Right RPM for stir plate?
Post by: narcout on January 18, 2015, 06:44:59 PM
I am going to try this.

It's hard!  I pitched my starter at 10:00 Wednesday night.  At 6:30 Thursday morning, it was already at high krausen.  By the time I got home from the gym after work on Thursday night, it was 8 o'clock and it had already fermented out.

My dunkel seems to be fermenting pretty strongly though

Next time, I'll have to ask my wife (who gets home from work a few hours earlier than I do) to stick it in the fridge for me.

One of the upgrades to my brewery that I am planning this year is a move to stainless fermentation vessels.

That is a seriously worthwhile upgrade.
Title: Re: Right RPM for stir plate?
Post by: denny on January 18, 2015, 06:45:27 PM
The data is just not there to prove that stir plates have improved the overall quality of beer.  What has improved the overall quality of home-brewed beer is access to higher quality/fresher ingredients (we used to get product for which there was no professional market), ready-made gear,  and the dissemination of knowledge.

I'd say my stir plate may have improved the quality of my beer.  But the main advantage has been quicker and easier yeast starters.
Title: Re: Right RPM for stir plate?
Post by: denny on January 18, 2015, 06:47:36 PM
My non-attempered fermentations run a degree or two higher in HDPE plastic buckets than they do in glass carboys, so it's real.  If you are using attemperation, then it does not matter what you use as a fermentation vessel.

With that said, my main aversion to HDPE plastic as a fermentation vessel material is biological followed closely by its odor retaining properties.  Regardless of how well one cleans and maintains one's gear, HDPE is a wild microflora magnet.   They only way that I have found to de-funk an HDPE bucket is filling it with caustic, and I prefer to avoid working with that stuff.  While I am not a fan of glass from a safety point of view, it beats HDPE plastic hands down from a microbiological point of view.  One of the upgrades to my brewery that I am planning this year is a move to stainless fermentation vessels.

I guess I'll just have to resolve myself to the fact that my beer sucks, then, and I'm not sophisticated enough to know the difference.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 18, 2015, 06:47:45 PM
like anything new in brewing, its appropriate to create like sample sizes for comparison. while stir plates are relatively new as you say, given the equal time period (say last 5-years for instance) of stir plate use compared to non stir plate use, great beers were produced (whether award winning and medal counting or not).

However, no data exists that clearly demonstrates that stir plates have improve the quality of home-brewed beer, which means that a stir plate is an unnecessary expense for most home brewers, especially brewers who are on a tight budget like I was when I first started to brew over twenty years ago.

On a different note, I just purchased a Corning 1395-5L (5000ml) media bottle to keep the Corning 1395-100 (100ml) media bottles that I use for first-level starters company.


Corning 1395-100 media bottles filled with autoclaved wort

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/MediaBottles_zpseed0bf41.jpg)

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/MediaBottle_zpsdff03f83.jpg)


Corning 1395-5L (the mother of all media bottles, that is, except for its bigger brother the 1395-10L)

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/hugemediabottle_zps9f619a1b.jpg)
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 18, 2015, 06:51:58 PM
I guess I'll just have to resolve myself to the fact that my beer sucks, then, and I'm not sophisticated enough to know the difference.

I am certain that your beer does not suck, but it has more to do with your level of expertise than any single step or piece of gear that you use.  A great musician can make beautiful music on a low-end instrument.  A poor musician will struggle to produce music that people can stand on a high-end instrument.
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 18, 2015, 07:02:17 PM

Brewing my 100th IPA beer right now. I am all about the hops. I have no problem whatsoever fermenting them at 68 and getting completely clean , super hop flavored beer. In fact I have found zero benefit to fermenting at 64 vs 68. In the summer it's 68, in the winter it's 64-66. If I thought there was a perceivable increase in quality, I would ferment them year round at the cooler temperature.

Whenever I look at a gold medal recipe, the fermentation temperature is rarely ever as low as 64, with 66-68 being the norm. Commercial recipes suggest those temps as well- even though most commercial brewers were/are homebrewers, if there were some great discrepancy I think they would make sure and correct it when giving recipes out for homebrewing.

In matters of opinion there is no argument, because you can't account for taste.

Yep, like I said, personal preference. As for pro brewers, a fair number ferment under pressure which inhibits ester formation , so it's 'apples to oranges' in terms of their temps. I'm willing to bet if you polled this forum, the vast majority of brewers (including the pro ones) ferment ales under 68F. I'm not saying it can't be done well.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 18, 2015, 07:11:15 PM
like anything new in brewing, its appropriate to create like sample sizes for comparison. while stir plates are relatively new as you say, given the equal time period (say last 5-years for instance) of stir plate use compared to non stir plate use, great beers were produced (whether award winning and medal counting or not).

However, no data exists that clearly demonstrates that stir plates have improve the quality of home-brewed beer, which means that a stir plate is an unnecessary expense for most home brewers, especially brewers who are on a tight budget like I was when I first started to brew over twenty years ago.


my data exists..and im sure a few others on here have data that exists. my beers have definitely improved with stir plate. that's not to say that if i had your yeast management equipment and testing equipment and knowledge, that I couldn't produce good results also.  just not as practical for most.
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 18, 2015, 07:22:52 PM
I'm going to pick on you here. Do you have a reference for this? What is the total count of awards won, and the % of non-stir vs stir? I've not seen competitions require the brewers to list what method of yeast propagation they used, but im new. Did they used to collect that info? Do any of these include awards won prior to the invention of electricity? Because that kind of unfairly stacks the deck in favor of the stirplatephobic hyperbole.

If we are counting NHC awards, then non-stir plate awards dwarf stir plate awards because the universal use of a stir plate is a relatively new thing.  If we are counting local competitions, then the numbers may be more even because of the explosion of local competitions.   

With that said, home brewers made award winning beers for three decades before a stir plate became a "must have."  The data is just not there to prove that stir plates have improved the overall quality of beer.  What has improved the overall quality of home-brewed beer is access to higher quality/fresher ingredients (we used to get product for which there was no professional market), ready-made gear,  and the dissemination of knowledge.
Maybe, but much of your award argument is based on your opinion rather than known gathered data, and the notion that award winning equates to best. I can't prove this, but I'm betting some of the more recent award winners are far superior to those from decades past. In the home brew world at least, maybe not so much gap in the pro world.

I'm tracking with you on your key point, I just think you are needlessly stretching a notion to make that point. A stirplate, in and of itself,  is no more devil than angel. I think your point is that they dont aerate like some might be lead to beleive, and you can crash before they completely ferment out. That's the gold nugget I found in this thread
Title: Re: Right RPM for stir plate?
Post by: klickitat jim on January 18, 2015, 07:26:33 PM
One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels.

Once again, though, your objection is more theoretical than actual, at least in my experience.  In practice, having used carboys, buckets, and cornies, the difference in thermal conductivity makes little to no difference in actual use.  Your experience may differ from that, but mine is that they work equally well in terms of thermal conductivity.
Denny, as an author of a how to book, what problems could you face by telling new brewere to place glass carboys on concrete?
Title: Re: Right RPM for stir plate?
Post by: denny on January 18, 2015, 07:49:30 PM
I guess I'll just have to resolve myself to the fact that my beer sucks, then, and I'm not sophisticated enough to know the difference.

I am certain that your beer does not suck, but it has more to do with your level of expertise than any single step or piece of gear that you use.  A great musician can make beautiful music on a low-end instrument.  A poor musician will struggle to produce music that people can stand on a high-end instrument.

But you just a much as said that buckets are unsuitable for fermentation.  That's what I use.  How can expertise overcome that?
Title: Re: Right RPM for stir plate?
Post by: denny on January 18, 2015, 07:53:42 PM
One of the reasons why I hate plastic buckets is that HDPE has the lowest thermal conductivity rating of the "big three" materials that are used in the construction of fermentation vessels.  Stainless has a terminal conductivity rating of 16 watts per meter kelvin (W/(m·K)). Glass has a thermal conductivity rating of 1.05 W/(m·K).  HDPE plastic has a thermal conductivity of 0.42 W/m-K.   In essence, HDPE traps heat better than any of the materials commonly used in constructing fermentation vessels.

Once again, though, your objection is more theoretical than actual, at least in my experience.  In practice, having used carboys, buckets, and cornies, the difference in thermal conductivity makes little to no difference in actual use.  Your experience may differ from that, but mine is that they work equally well in terms of thermal conductivity.
Denny, as an author of a how to book, what problems could you face by telling new brewere to place glass carboys on concrete?

I imagine there could be liability issues.  In EHB, we had to place disclaimers on things like gathering your own mushrooms or using caffeine powder.  Not to mention, having broken carboys by placing them on carpeted concrete floors, I couldn't in good conscience advise anyone to do it.
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 18, 2015, 07:58:35 PM
  Not to mention, having broken carboys by placing them on carpeted concrete floors, I couldn't in good conscience advise anyone to do it.

Yeah, wish I had a 'do over' on the 2 I broke back then. Glad it wasn't worse than it was.
Title: Re: Right RPM for stir plate?
Post by: narcout on January 19, 2015, 12:35:59 AM
On a different note, I just purchased a Corning 1395-5L (5000ml) media bottle to keep the Corning 1395-100 (100ml) media bottles that I use for first-level starters company.

Damn, those things are expensive! What's the advantage over a 5L flask, other than the screw top?
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 19, 2015, 03:25:48 AM
Damn, those things are expensive! What's the advantage over a 5L flask, other than the screw top?

The autoclavable GL45 screw cap is a major advantage when shaking, and a Corning 4995-6L screw-cap Erlenmeyer flask is even more expensive (Corning does not make a 5L screw-cap Erlenmeyer).  There is also an autoclavable pouring ring under the screw cap that makes accurate pouring much easier.  Plus, it is much easier to find NOS (new old stock) surplus large media bottles than it is NOS large screw cap Erlenmeyer flasks, and I never purchase any screw cap lab glassware used because one does not know what was previously stored in used glassware.  Purchasing used means replacing the cap(s), which usually have to be purchased in quantity.  For example, I purchased a sizable lot of NOS Corning 125mm x 20mm screw cap culture tubes.  The tubes came with unused caps, but they were the wrong size cap (someone must have mixed up the lot).  I wound up having to order 192 caps at a cost of around $70.00 + shipping from a scientific supply house, which made a great deal an okay deal.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 19, 2015, 03:35:54 AM
But you just a much as said that buckets are unsuitable for fermentation.  That's what I use.  How can expertise overcome that?

You are more than likely meticulous with your cleaning, sanitation, and handling.  You are also fermenting low, which will prevent most native flora from starting.   If your ales improved when you went below 66F, here's your sign.

Post-posting addition:

By the way, I did not say that buckets were unsuitable for use as fermentation vessels. I stated my reasons why I consider HDPE buckets unsuitable for use in my brew house.  A brewer can use anything that he/she wants as a primary fermentation vessel as long as he/she is aware the downsides.  Glass definitely has a major downside in that it is fragile and breaks into sharp pieces.  However, glass is also non-porous; therefore, it blocks gas exchange and does not harbor microflora. It's also easier to sanitize and sterilize.  It is up to a brewer to decide if a non-porous, much easier to sanitize surface is worth the extra risk. 
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 19, 2015, 04:25:11 AM
I'm willing to bet if you polled this forum, the vast majority of brewers (including the pro ones) ferment ales under 68F.

I am willing to bet that if you polled this forum, you would find that the vast majority of all-grain brewers batch sparge.  What does that tell you?  It tells me that they were steered toward the process on forums such as this one just as new brewers are steered toward temperature-controlled fermentation and rinsing yeast with boiled water on forums such as this one.  A hobby that was built on rugged individualism is starting to experience "groupthink," which does no one good in the long run.
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 19, 2015, 01:40:19 PM
I'm willing to bet if you polled this forum, the vast majority of brewers (including the pro ones) ferment ales under 68F.

I am willing to bet that if you polled this forum, you would find that the vast majority of all-grain brewers batch sparge.  What does that tell you?  It tells me that they were steered toward the process on forums such as this one just as new brewers are steered toward temperature-controlled fermentation and rinsing yeast with boiled water on forums such as this one.  A hobby that was built on rugged individualism is starting to experience "groupthink," which does no one good in the long run.

Except in this case, the 'groupthink' very likely produces damn good beer, which is the goal,no ? Or is the goal for everyone to take your advice ?  My liking my beer fermented at cool temps better than higher temps doesn't make me a blind follower - it means I've made a lot of beer and prefer it that way. Just like I prefer batch sparging for its simplicity - I couldn't give a damn if it works for somebody else. I brew beer for me first and foremost, though I'd be happy to share.  ;)
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 19, 2015, 04:11:40 PM
I would hope that the goal of every brewer would be to keep an open mind, not take the "What I am doing works for me, so why try something different?" approach to brewing.  The only approach that I can think of that is more dangerous to the future of home brewing is the lemming approach of following the crowd without question.  If every home brewer took either of these approaches to home brewing, we would still be making beer from cans of Pabst Blue Ribbon malt extract and baker's yeast.

When it comes to yeast management, my goal is and has always been to make the process simpler and more foolproof.  I have done so because I have propagated almost every culture that I have used in brewing from one of these since batch #4:

(http://i699.photobucket.com/albums/vv356/tonestack/Brewing/CCyeast1_zpsdc754fa7.jpg)

If I took the approach to yeast propagation that most home brewers take today, it would take me a week or more to propagate a culture from slant.  Using the method outlined in this thread, I can go from a 4mm nichrome loop scrape from a slant to a healthy pitchable culture in as little as two days.

Contrary to what many forum readers may assume, I am not using any hi-tech equipment to maintain and propagate my yeast bank.  The basic process and equipment that I use have been around since the end of the nineteenth century.  While I use fancy lab glassware today, I started out using 4oz baby food jars for slants, plates, and sterile liquid media because the liners on the caps of baby food jars can withstand repeated autoclaving.  I did so because I was on a tight brewing budget at that point in time.  I continued to use 4oz baby food jars for my absolutely sterile first-level starters for ten years after I started to use screw cap culture tubes for slants and glass and pre-sterilized plastic petri dishes for plates.  I only switched to using 100ml media bottles instead of 4oz baby food jars because my sources for used baby food jars dried up, and I have more disposable income than I did when I first started to brew.

In essence, while the Internet has made high quality labware and culturing supplies available to people with non-laboratory addresses, I can teach a brewer how to maintain a healthy yeast bank on solid media using a home pressure canner/cooker, glassware found in a supermarket, and agar flakes found in most health food stores.  There's no freedom like being free from the major yeast suppliers.   There's also no freedom like having every brewing culture that has been deposited in culture collections around the world at one's disposal as well as the ability capture and isolate wild microflora.

In closing, nothing is learned by playing it safe and waiting for someone else to try something new or revisit something old with a new perspective.  If one is not producing a less than stellar batch from time to time that cannot be attributed to an accident, one is not growing as a brewer. I have tried many different approaches to yeast management since I started to maintain yeast bank.  Some approaches have worked, but most have produced less than desirable results.  I routinely pitch yeast cultures for which I have almost no brewing data into batches of wort that I spent four or more hours producing.  I have no idea as to how the batch will turn out or if I have selected the right recipe for the culture.  Heck, I do not even know if I am pitching a spoilage strain that I spent a c-note or more acquiring because the information available for most culture collection strains is minimal at best.  However, I learn something new with every pitch.  The information that I have shared about practical yeast management on this forum came about from theory plus practice, which is the engineering method of learning.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 19, 2015, 04:26:19 PM
I would hope that the goal of every brewer would be to keep an open mind, not take the "What I am doing works for me, so why try something different?" approach to brewing.  The only approach that I can think of that is more dangerous to the future of home brewing is the lemming approach of following the crowd without question.  If every home brewer took either of these approaches to home brewing, we would still be making beer from cans of Pabst Blue Ribbon malt extract and baker's yeast.

great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 19, 2015, 04:33:41 PM
I would hope that the goal of every brewer would be to keep an open mind, not take the "What I am doing works for me, so why try something different?" approach to brewing.  The only approach that I can think of that is more dangerous to the future of home brewing is the lemming approach of following the crowd without question.  If every home brewer took either of these approaches to home brewing, we would still be making beer from cans of Pabst Blue Ribbon malt extract and baker's yeast.

great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"

^^^^^^.  Whirlpool hopping, experimenting with non traditional ingredients............
Title: Re: Right RPM for stir plate?
Post by: denny on January 19, 2015, 05:47:00 PM
I would hope that the goal of every brewer would be to keep an open mind, not take the "What I am doing works for me, so why try something different?" approach to brewing.  The only approach that I can think of that is more dangerous to the future of home brewing is the lemming approach of following the crowd without question.  If every home brewer took either of these approaches to home brewing, we would still be making beer from cans of Pabst Blue Ribbon malt extract and baker's yeast.

great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"

Exactly right!  I didn't start doing any of those things becasue someone else simply said to do them, and I hope people don't look at my advice like that.  Collect info, analyze it through the filter of your experience, try it and decide for yourself if it works for you.
Title: Re: Right RPM for stir plate?
Post by: S. cerevisiae on January 19, 2015, 05:47:17 PM
great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"

Ken, let me ask you a couple of questions.  How many sparging techniques have you studied and practiced to the point where you actually developed a level of expertise that elevated you above that of rank beginner?  How many yeast propagation techniques have you practiced to the point where you feel that you can achieve maximum performance out of the technique?  If the answer to either question is one, maybe two, then how do you know that the techniques you are using are best of breed? 

Throughout this discussion, you have attempted to argue the point that many brewers get acceptable results from stir plates; therefore, why should they try something different?  However, I have brought to light in more than one post that the smell and taste of a healthy culture does not differ from that of unhopped beer, and the goal of a starter is to increase healthy biomass that is ready to go to work upon pitching.   Off-aromas and off-flavors are signs that a culture is stressed, and a stressed culture is an unhealthy culture.   No one argues that off-aromas and off-flavors are often signs of yeast stress in a fermentation.  Yet, brewers who use stir plates go through great extents to decant their "foul" starter wort without questioning why their starter wort is foul.  A healthy starter is pitchable without decanting.

Remember, all of the techniques that you mentioned were the result of someone taking a chance as well as the heat for going against commonly accepted practice.  I know that I what I am asking people to try goes against what they do or have read on forums.  I guarantee that everything that I have posted in this thread is backed up by years of applying theory in an attempt to truly understand how the organisms that actually make beer work in a practical setting. 
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 19, 2015, 06:09:29 PM
great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"

Ken, let me ask you a couple of questions.  How many sparging techniques have you studied and practiced to the point where you actually developed a level of expertise that elevated you above that of rank beginner?  How many yeast propagation techniques have you practiced to the point where you feel that you can achieve maximum performance out of the technique?  If the answer to either question is one, maybe two, then how do you know that the techniques you are using are best of breed? 

Throughout this discussion, you have attempted to argue the point that many brewers get acceptable results from stir plates; therefore, why should they try something different?  However, I have brought to light in more than one post that the smell and taste of a healthy culture does not differ from that of unhopped beer, and the goal of a starter is to increase healthy biomass that is ready to go to work upon pitching.   Off-aromas and off-flavors are signs that a culture is stressed, and a stressed culture is an unhealthy culture.   No one argues that off-aromas and off-flavors are often a sign of yeast stress in a fermentation.  Yet, brewers who use stir plates go through great extents to decant their "foul" starter wort without questioning why their starter wort is foul.  A healthy starter is pitchable without decanting.

Remember, all of the techniques that you mentioned were the result of someone taking a chance as well as the heat for going against commonly accepted practice.  I know that I what I am asking people to try goes against what they do or have read on forums.  I guarantee that everything that I have posted in this thread is backed up by years of applying theory in an attempt to truly understand how the organisms that actually make beer work in a practical setting.

for simplicity sake, let me say this: i'm not even remotely saying or suggesting my practices are the best, the only way, or qualify me or my beer as "the best".

i can tell you with certainty that when I try something different, and I can perceive the positive difference in the finished product...that's as real as it gets. Ive failed more times than succeeded in the beginning. I can say Ive continued to explore the possibilities and have adapted accordingly. I don't do things just because someone says its the way to do it-instead, I evaluate the proposition, consider the facts, and then decide if experimentation is in order.....more often than not I'll give it a shot out of curiosity.

So have my brewing practices, processes, and method's changed over the last 3-years-absolutely! Has my beer improved significantly, and to the point I'm proud to say I have a really good finished product- again, absolutely. Will there be more opportunity to improve- absolutely.

Contrary to what you may think, I'm not saying your suggestions about starters and yeast management are wrong. I'm just feeling your position in this thread has taken a turn towards saying , "if you don't do it the way outlined and you use a stir plate, your beer cant be as good as the beer made without a stir plate following the yeast management practices you've outlined here". its just not that simple IMO.

EDIT: FWIW, my starters don't stink and really don't taste foul at all. Just tasted london ale starter this weekend for my porter-tastes like beer, smells like beer. on stir plate low speed for about 18hrs, cold crashed, and mostly decanted before pitching.
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 19, 2015, 06:38:51 PM
On a final note (said all i can say), my only hope is new (and seasoned alike i guess) brewers take away the following from this thread:  We are not curing cancer here...we are brewing beer. At the end of the day, just enjoy what you are doing, ask questions and challenge everything. By doing so you'll free yourself to the possible, and somewhere along the journey you'll find a path you can call your own.  If whatever you do in the process of making beer works for you and you're happy with your finished product...that's all that really matters.

For the love of beer-peace out!  ;D
Title: Re: Right RPM for stir plate?
Post by: hopfenundmalz on January 19, 2015, 06:41:44 PM
I would hope that the goal of every brewer would be to keep an open mind, not take the "What I am doing works for me, so why try something different?" approach to brewing.  The only approach that I can think of that is more dangerous to the future of home brewing is the lemming approach of following the crowd without question.  If every home brewer took either of these approaches to home brewing, we would still be making beer from cans of Pabst Blue Ribbon malt extract and baker's yeast.

great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"

The Bruelosophy schedule is pretty much what I have been doing for the last 3-4 years. Most of what I got was from Kai's page. Comments. Go on gravity, as sometimes I start the D-rest after 4 days for a 12 P beer, or it might take 6 or more for a 20+ P beer that is fermented at 48F. Check the flavor during the D-rest, you might not need 5 days. Crash to -1C (30.2F if you are SI challanged). Give it time to clear.
Title: Re: Right RPM for stir plate?
Post by: denny on January 19, 2015, 06:41:59 PM
On a final note (said all i can say), my only hope is new (and seasoned alike i guess) brewers take away the following from this thread:  We are not curing cancer here...we are brewing beer. At the end of the day, just enjoy what you are doing, ask questions and challenge everything. By doing so you'll free yourself to the possible, and somewhere along the journey you'll find a path you can call your own.  If whatever you do in the process of making beer works for you and you're happy with your finished product...that's all that really matters.

For the love of beer-peace out!  ;D

GOLD STAR!!!!

(http://www.trickymisfit.com/goldstar.gif)
Title: Re: Right RPM for stir plate?
Post by: HoosierBrew on January 19, 2015, 06:44:24 PM
On a final note (said all i can say), my only hope is new (and seasoned alike i guess) brewers take away the following from this thread:  We are not curing cancer here...we are brewing beer. At the end of the day, just enjoy what you are doing, ask questions and challenge everything. By doing so you'll free yourself to the possible, and somewhere along the journey you'll find a path you can call your own.  If whatever you do in the process of making beer works for you and you're happy with your finished product...that's all that really matters.

For the love of beer-peace out!  ;D

^^^^^^^^^^^ Gold star, also. 
Title: Re: Right RPM for stir plate?
Post by: Wort-H.O.G. on January 19, 2015, 06:46:40 PM
I would hope that the goal of every brewer would be to keep an open mind, not take the "What I am doing works for me, so why try something different?" approach to brewing.  The only approach that I can think of that is more dangerous to the future of home brewing is the lemming approach of following the crowd without question.  If every home brewer took either of these approaches to home brewing, we would still be making beer from cans of Pabst Blue Ribbon malt extract and baker's yeast.

great points.  this is how brewers navigated to using stir plates, batch sparge, brulosophy lager schedule, etc....-"open mind to trying something different"

The Bruelosophy schedule is pretty much what I have been doing for the last 3-4 years. Most of what I got was from Kai's page. Comments. Go on gravity, as sometimes I start the D-rest after 4 days for a 12 P beer, or it might take 6 or more for a 20+ P beer that is fermented at 48F. Check the flavor during the D-rest, you might not need 5 days. Crash to -1C (30.2F if you are SI challanged). Give it time to clear.

Jeff- I agree on the gravity reading. first time I did it, i felt it was a tad early for day 5 to ramp up. I'm finding for me, i start the clock from first signs of fermentation, and therefore around day 6 im in the 60% attenuation range. its then i start the ramp up in temps.
Title: Re: Right RPM for stir plate?
Post by: Hooper on January 21, 2015, 01:55:33 AM
When I saw the start of this thread, I laughed out loud. Now 11 pages in...What an interesting read and I learned some things along the way. I guess you can't judge a book by it's cover...
Title: Re: Right RPM for stir plate?
Post by: TMX on January 25, 2015, 11:17:13 PM
I have read every post of this thread at least twice, and some of them up to 5-6 times.  I have had several PM conversations with Mark, and he has been very helpful in helping me understand his method.  I brew 10 gallon batches, and today I ordered 2 1 gallon jugs with poly screw caps to give his method a try.

I do not have a LBS that I care to deal with that had the jars, so less than $20 later (free shipping) I have the items I need to try something new that may improve my beer.

For some reason, if I can't get the results I am looking for, then worst case I have 2 1 gallon growlers for carrying my home brew to a friends house.

I got stale and stuck with my approach to brewing, completely going against the reason I started in the first place.  As brewers, almost everything we do gas against the grain, or is off the beaten path; being unable to accept, try, or at least contemplate a new technique is just strange to me.

I have an Irish planned for my next brew day, I will report back with the results and pics, if i can remember to take them.

Tim
Title: Re: Right RPM for stir plate?
Post by: brewday on January 25, 2015, 11:33:40 PM
I have read every post of this thread at least twice, and some of them up to 5-6 times.  I have had several PM conversations with Mark, and he has been very helpful in helping me understand his method.  I brew 10 gallon batches, and today I ordered 2 1 gallon jugs with poly screw caps to give his method a try.

I do not have a LBS that I care to deal with that had the jars, so less than $20 later (free shipping) I have the items I need to try something new that may improve my beer.

For some reason, if I can't get the results I am looking for, then worst case I have 2 1 gallon growlers for carrying my home brew to a friends house.

I got stale and stuck with my approach to brewing, completely going against the reason I started in the first place.  As brewers, almost everything we do gas against the grain, or is off the beaten path; being unable to accept, try, or at least contemplate a new technique is just strange to me.

I have an Irish planned for my next brew day, I will report back with the results and pics, if i can remember to take them.

Tim

Nice!  Yes, updates please.

I just pitched my second no-stir starter since this thread began.  The first was kegged this morning and I'll probably get around to sampling it by mid week.
Title: Re: Right RPM for stir plate?
Post by: TMX on January 26, 2015, 12:58:02 AM
@brewday

let us know your thoughts so far on the James Bond (shaken not stirred) method.....
Title: Re: Right RPM for stir plate?
Post by: brewday on January 26, 2015, 01:59:28 AM
The first is a 1.057 American Amber and the second is a 1.055 ESB.  I've brewed them a few times before.  Both got the Fullers strain.  I used the Mr. Malty YC to determine starter size with one smack pack.  I'm using a 5L flask, pure O2, stopper w/airlock and crashing at high krausen.  No stir plate.

I crashed the Amber starter (1.9L) at 18 hours and decanted.  I actually missed high krausen I think, judging by the braun hefe (or is that bruno hefe, eh Keith?  ;D) on the flask.  I have no idea what the final yeast count was, but there was a lot of yeast.  Besides, I think the point of this method is volume of viable, non-stressed yeast vs total stirred volume.  Anyway, there was a lot if yeast.  Fermentation seemed typical for the most part, though it did finish lower than usual (1.010 vs 1.012-13).  This is the Amber Ale that I referenced in another thread regarding quick turnaround time.

For the ESB today, a 1.1L starter, crashed at 13 hours, decanted and pitched 5 hours later.  This one's going to comp, which says a lot about my confidence in this method.

We'll see what happens!


Title: Re: Right RPM for stir plate?
Post by: bbt95762 on June 03, 2017, 11:40:52 PM
I'd always thought the main point of the stir plate was to knock the CO2 out of suspension, as CO2 in the wort discourages/slows yeast growth.  Thanks for all the pointers in the thread, I'll just keep it at a slow speed.
Title: Re: Right RPM for stir plate?
Post by: 69franx on June 13, 2017, 08:04:49 PM
Kind of neat that this got such a late reply. Looking back at the first page, it seems to be the beginnings of Mark's explanation of SNS, or at least very early in that discussion. Thanks for bringing this back to life
Title: Re: Right RPM for stir plate?
Post by: bbt95762 on June 13, 2017, 09:18:32 PM
yah, noticed that after I'd replied - probably should have just not replied :)
Title: Re: Right RPM for stir plate?
Post by: 69franx on June 14, 2017, 03:16:27 AM
No it's an awesome, life changing thread

Sent from my XT1635-01 using Tapatalk

Title: Re: Right RPM for stir plate?
Post by: Philbrew on June 14, 2017, 02:55:12 PM
Kind of neat that this got such a late reply. Looking back at the first page, it seems to be the beginnings of Mark's explanation of SNS, or at least very early in that discussion. Thanks for bringing this back to life
Yeah, it's where SNS got its name.  On page 5 I lamely attempted some humor and posted:
"S. cerevisiae,
You should go by James Bond 007.  Shaken not stirred, you wouldn't want to bruise the yeast. :-)"

The name stuck (the SNS part).
Title: Re: Right RPM for stir plate?
Post by: 69franx on June 14, 2017, 03:53:03 PM
Awesome. I went back and read the first and last 2 pages again. Guess I had forgotten how heated this debate was 2.5 years ago. Like I said, glad it popped. Ack up on the radar

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