Author Topic: Right RPM for stir plate?  (Read 16854 times)

S. cerevisiae

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Re: Right RPM for stir plate?
« Reply #30 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.   

Offline Wort-H.O.G.

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Re: Right RPM for stir plate?
« Reply #31 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.
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Re: Right RPM for stir plate?
« Reply #32 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?
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S. cerevisiae

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Re: Right RPM for stir plate?
« Reply #33 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.

S. cerevisiae

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Re: Right RPM for stir plate?
« Reply #34 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.

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Re: Right RPM for stir plate?
« Reply #35 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.
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S. cerevisiae

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Re: Right RPM for stir plate?
« Reply #36 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.

Offline Philbrew

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Re: Right RPM for stir plate?
« Reply #37 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.
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Offline morticaixavier

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Re: Right RPM for stir plate?
« Reply #38 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.

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Offline Philbrew

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Re: Right RPM for stir plate?
« Reply #39 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.
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Re: Right RPM for stir plate?
« Reply #40 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.
Ken- Chagrin Falls, OH
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https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

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Vienna IPA          O'Fest
Dort
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Cider                         
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Ger Pils
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S. cerevisiae

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Re: Right RPM for stir plate?
« Reply #41 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. 

Offline Philbrew

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Re: Right RPM for stir plate?
« Reply #42 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?
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S. cerevisiae

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Re: Right RPM for stir plate?
« Reply #43 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. 

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Re: Right RPM for stir plate?
« Reply #44 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.
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