Homebrewers Association | AHA Forum

General Category => Yeast and Fermentation => Topic started by: S. cerevisiae on June 16, 2015, 11:20:00 am

Title: Yeast propagation at White Labs
Post by: S. cerevisiae on June 16, 2015, 11:20:00 am
I hope that everyone who took the White Labs tour noticed the big orbital shaker table in the propagation lab.  I did not see a single stir plate in use at White Labs.
Title: Re: Yeast propagation at White Labs
Post by: denny on June 16, 2015, 11:38:48 am
I hope that everyone who took the White Labs tour noticed the big orbital shaker table in the propagation lab.  I did not see a single stir plate in use at White Labs.

I'll stop using mine as soon as I get a big orbital shaker table!  In the meanwhile, I've proven to myself that a stir plate works better and faster than any other method I've tried.
Title: Re: Yeast propagation at White Labs
Post by: brewinhard on June 16, 2015, 11:44:30 am
I hope that everyone who took the White Labs tour noticed the big orbital shaker table in the propagation lab.  I did not see a single stir plate in use at White Labs.

Was there any oxygen being pumped into this at all? 
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 16, 2015, 11:52:29 am
Not that I saw, but I only was able to get a glimpse of the room.  The flasks appeared to be standard Erlenmeyer flasks instead of Fernbach flasks.   A Fernbach flask looks like a squat Erlenmeyer flask. Fernback flasks are made for shaking.
Title: Re: Yeast propagation at White Labs
Post by: rjharper on June 16, 2015, 12:01:57 pm
It's a lot easier (and cheaper) to put a dozen flasks on a shaker table, than line up 12 spinning magnets. I did notice they still use foil crimped around the mouth of the flask, just like us!
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 16, 2015, 01:03:54 pm
Actually, a shaker table is the preferred laboratory device for propagating yeast.  What shaking does is aerate the culture in a low stress way.  Spinning the stir bar fast enough to aerate a culture on a stir plate can place significant shear stress on the cells, resulting in an unhealthy culture. That's why many stirred cultures smell foul.
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 16, 2015, 01:05:50 pm
By the way, a shaker table the size that is used at White Labs is significantly more expensive than a comparable number of stir plates.
Title: Re: Yeast propagation at White Labs
Post by: rjharper on June 16, 2015, 01:31:50 pm
Actually, a shaker table is the preferred laboratory device for propagating yeast.  What shaking does is aerate the culture in a low stress way.  Spinning the stir bar fast enough to aerate a culture on a stir plate can place significant shear stress on the cells, resulting in an unhealthy culture. That's why many stirred cultures smell foul.

Very interesting. I'm certainly not going to go against your yeast advice Mark. And I only push the stir bar fast enough to get things moving and roused, not to force a maelstrom in the flask!
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 16, 2015, 02:29:23 pm
In my humble opinion, stir plates have been sold to home brewers based on claims that do not hold up under close inspection.  Stirring briskly enough to aerate a culture can result in unhealthy cells due to shear stress.  Stirring slowly does not add much in the way of value because most brewing strains are either non-flocculent or exhibit NewFlo flocculation (FLO is the name for the set of genes that control flocculation).  NewFlo strains remain in suspension until glucose, mannose, maltose, sucrose, and maltotriose reach a genetically set level, and non-flocculent strains seem to want to remain in suspension forever; hence, cells that exhibit either type of flocculation will remain in suspension long enough to achieve maximum cell density without stirring.

Now, there are those who claim that stirring results in higher cells counts.  However, I have never seen viability stain results accompany these claims.  A solution is capable of supporting a maximum number of viable cells.  This number is known as the maximum cell density. Yeast cultures are self-moderating in that all new biomass growth is for replacement purposes only after maximum cell density has been reached. 

The goal of making a starter should be to reach maximum cell density while preserving cellular health, which is why I promote pitching a well-aerated starter at high krausen.  High krausen occurs when maximum cell density has been reached. One should experience high krausen with a 1 to 2 liter starter roughly 12 to 18 hours after inoculation.  Older cultures will take longer to reach high krausen than newer cultures.  Allowing a starter to ferment beyond high krausen results in unnecessary ergosterol and unsaturated fatty acid depletion.  Allowing a starter to ferment to completion places the cells in the yeast equivalent of hibernation.

Title: Re: Yeast propagation at White Labs
Post by: jeffjm on June 17, 2015, 07:59:27 am
I completely get the idea of having the cells be active.  On the other hand,  I don't want to dilute my batch with several liters of starter wort. How can you minimize the amount of starter wort pitched while keeping the cells active?
Title: Re: Yeast propagation at White Labs
Post by: denny on June 17, 2015, 08:58:16 am
In my humble opinion, stir plates have been sold to home brewers based on claims that do not hold up under close inspection.  Stirring briskly enough to aerate a culture can result in unhealthy cells due to shear stress.  Stirring slowly does not add much in the way of value because most brewing strains are either non-flocculent or exhibit NewFlo flocculation (FLO is the name for the set of genes that control flocculation).  NewFlo strains remain in suspension until glucose, mannose, maltose, sucrose, and maltotriose reach a genetically set level, and non-flocculent strains seem to want to remain in suspension forever; hence, cells that exhibit either type of flocculation need help remaining in suspension long enough to achieve maximum cell density.

Now, there are those who claim that stirring results in higher cells counts.  However, I have never seen viability stain results accompany these claims.  A solution is capable of supporting a maximum number of viable cells.  This number is known as the maximum cell density. Yeast cultures are self-moderating in that all new biomass growth is for replacement purposes only after maximum cell density has been reached. 

The goal of making a starter should be to reach maximum cell density while preserving cellular health, which is why I promote pitching a well-aerated starter at high krausen.  High krausen occurs when maximum cell density has been reached. One should experience high krausen with a 1 to 2 liter starter roughly 12 to 18 hours after inoculation.  Older cultures will take longer to reach high krausen than newer cultures.  Allowing a starter to ferment beyond high krausen results in unnecessary ergosterol and unsaturated fatty acid depletion.  Allowing a starter to ferment to completion places the cells in the yeast equivalent of hibernation.

Mark, I hope you know that I have great respect for your knowledge and experience.  But what am I to do when my direct experience contradicts that knowledge?  I don't have the equipment to count cells or assess viability.  I have to base my techniques solely on performance and results.  For many years, I simply shook my starters as you advise.  It worked fine.  But once I was given a stir plate, I found that I could grow more yeast in a shorter time than shaking.  In addition, I got (subjectively) better results using the yeast grown on a stir plate.  So, how do I reconcile my results with your advice?
Title: Re: Yeast propagation at White Labs
Post by: brewinhard on June 17, 2015, 09:23:52 am
I completely get the idea of having the cells be active.  On the other hand,  I don't want to dilute my batch with several liters of starter wort. How can you minimize the amount of starter wort pitched while keeping the cells active?

+1.  That is my major concern as well.  How does one handle this issue?
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 17, 2015, 09:33:37 am
As I have mentioned many times on this forum, yeast cultures are kind of like nuclear weapons in that one only needs to be within a reasonable distance from one's target in order to accomplish the task.   The difference in propagation time between a 1L starter and a 2L start is one replication period (approximately 90 minutes); hence, very little is gained by pitching 2L starter.  Nothing is gained by pitching a 2L starter that has reached quiescence over pitching a 1L starter at high krausen. 

In my humble opinion, modern home brewing yeast pitching dogma is doing more harm than good.  My discussions with the brewers at White Labs only confirmed this belief.  I have pitched as little as 3 billion cells per liter of wort and as much as 20 billion cells per liter of wort.  Both pitching rates created good beer.  The difference between the two extremes is that the 3 billion cells per liter rate allowed the yeast to express its unique character whereas the 20 billion cell pitching rate produced a more generic flavored beer.  Granted, one has to pitch more cells per liter with high gravity beers, but that's only because high osmotic pressure coupled high ethanol levels take their toll on yeast cells, and it is more difficult to dissolve O2 in high gravity wort than it is in lower gravity wort.

Those who have tried my starter method have reported improved fermentation characteristics. A large part of that improvement is pitching at high krausen.  A starter made with extra light DME (e.g., Briess Pilsen) that is shaken until the media is mostly foam at the beginning of fermentation, and not stirred will be very neutral in flavor.  A 5% increase in final boil gravity will allow for a dilution rate of 1L per 5 gallons.  I guarantee that pitching at high krausen instead of waiting until quiescence has been reached will cut your starter volume in half because the cells have not depleted their ergosterol and unsaturated fatty acid reserves, nor have they undergone the survival-related morphological changes that occur at the end of fermentation.  A 1L starter that is pitched at high krausen will usually double cell count-wise by the time that a 2L starter that is pitched after quiescence had been reached exits the lag phase.  The net O2 load from the 1L starter will also be lower because one half of the cells at this point came into the game with non-depleted ergosterol and UFA reserves.  This difference results in a healthier fermentation.

If that information is not enough to convince you, the difference between pitching 200 billion cells and 400 billion cells is insignificant when pitching normal gravity wort.  The maximum cell density for 1L of wort is approximately 200 billion cells.  This limit is controlled by cell size.  The maximum cell density for a 5-gallon batch is 19 * 200 billion = 3.8 trillion cells; hence, neither pitching rate will saturate a 5-gallon batch of wort without significant growth.  As the cell count grows at a rate of 2n, where n equals elapsed clock time divided by the number of minutes in a replication period (around 90 minutes under ideal conditions), the minimum number of doubling periods that are required for each starter size to saturate the wort are as follows:

four_hundred_billion_cell_starter_replication_periods = log(3,800 / 400) / log(2) =  log(9.5) / log(2) = ~4 (arithmetic ceiling taken)

two_hundred_billion_cell_starter_replication_periods = log(3,800 / 200) / log(2) =  log(19) / log(2) = ~5 (arithmetic ceiling taken)

Title: Re: Yeast propagation at White Labs
Post by: narcout on June 17, 2015, 10:00:24 am
I have pitched as little as 3 billion cells per liter of wort and as much as 20 billion cells per liter of wort.  Both pitching rates created good beer.  The difference between the two extremes is that the 3 billion cells per liter rate allowed the yeast to express its unique character whereas the 20 billion cell pitching rate produced a more generic flavored beer.

four_hundred_billion_cell_starter_replication_periods = log(3,800 / 400) / log(2) =  log(9.5) / log(2) = ~4 (arithmetic ceiling taken)

two_hundred_billion_cell_starter_replication_periods = log(3,800 / 200) / log(2) =  log(19) / log(2) = ~5 (arithmetic ceiling taken)

At what point does the number of replication periods begin to have an effect on beer flavor?  I suppose it probably depends on strain and other factors, but are there any studies on this that you are aware of?
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 17, 2015, 01:16:44 pm
At what point does the number of replication periods begin to have an effect on beer flavor?  I suppose it probably depends on strain and other factors, but are there any studies on this that you are aware of?

That is a good question for which I do not have a definitive answer.
Title: Re: Yeast propagation at White Labs
Post by: Steve Ruch on June 17, 2015, 03:41:15 pm
I hope that everyone who took the White Labs tour noticed the big orbital shaker table in the propagation lab.  I did not see a single stir plate in use at White Labs.

I'll stop using mine as soon as I get a big orbital shaker table!  In the meanwhile, I've proven to myself that a stir plate works better and faster than any other method I've tried.

So, get a stir plate?
Title: Re: Yeast propagation at White Labs
Post by: narvin on June 17, 2015, 05:32:50 pm
Actually, a shaker table is the preferred laboratory device for propagating yeast.  What shaking does is aerate the culture in a low stress way.  Spinning the stir bar fast enough to aerate a culture on a stir plate can place significant shear stress on the cells, resulting in an unhealthy culture. That's why many stirred cultures smell foul.

Mine smells delightful, thank you very much  :D
Title: Re: Yeast propagation at White Labs
Post by: narvin on June 17, 2015, 06:06:31 pm

In my humble opinion, modern home brewing yeast pitching dogma is doing more harm than good.  My discussions with the brewers at White Labs only confirmed this belief.

After trying their beers at the tasting room, I'm not sure I trust their palate on brewing advice.  They know how to grow yeast, but I don't think they've figured out the optimal fermentation parameters for making any of the beer styles they had on tap last week.

I'm not going to make a beer with 5% DME... period.  Canned wort is even worse, since the malt oxidation is so extreme by the time I pop the top that it smells like honey.

Given that I don't have time to shake a starter more than once at the beginning, using a stir plate creates more yeast slurry than not using one, every time.  This makes it easier to get to my desired pitch rate for a given beer style.  I decant and pitch the slurry from the bottom, just like every commercial brewery that doesn't top crop.  The yeast is viable after staining.  The beer is happy.  The times I've been disappointed, actually, are when I start directly with a White Labs pitch  :)
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 17, 2015, 09:46:01 pm
Given that I don't have time to shake a starter more than once at the beginning, using a stir plate creates more yeast slurry than not using one, every time.  This makes it easier to get to my desired pitch rate for a given beer style.
 

A stir plate does not allow one to exceed maximum cell density.  A stir plate does not provide much in the way of aeration when run at a speed low enough to prevent shear stress.  Any increase in yeast biomass is the result of cells that have kicked the bucket.  Continuous propagation overcomes the maximum cell density problem by continuously removing yeast cells.

Quote
I decant and pitch the slurry from the bottom, just like every commercial brewery that doesn't top crop.

However, that's not how breweries perform an initial pitch.  Breweries that do not own a propagator usually start by inoculating an initial amount of wort at a rate of 1L of purchased yeast per barrel.  This initial inoculation is stepped at a rate of 10 to 1 when the propagation media reaches approximately 50% attenuation. 

Quote
  The yeast is viable after staining.  The beer is happy. 

Please post microscope photo a methylene blue stained slide of your yeast. 

Quote
The times I've been disappointed, actually, are when I start directly with a White Labs pitch

No one is suggesting that one should perform a direct pitch.  One of the critical things that a starter does when using White Labs yeast is allow the yeast cells to wake up and reverse the survival-related morphological changes that they underwent at the end of batch fermentation at White Labs in a relatively low density, high yeast cell to wort volume environment.  This step is critical because the remaining viable cells have usually had time to consume a good percentage of their glycogen stores. 
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 17, 2015, 09:48:41 pm
So, get a stir plate?

You do not need waste money on a stir plate.  Do yourself a favor search the forum using the terms "shaken, not stirred" and "James Bond Method."  You probably already own everything that you need to make a healthy starter using this method.
Title: Re: Yeast propagation at White Labs
Post by: narvin on June 18, 2015, 07:46:00 am
Given that I don't have time to shake a starter more than once at the beginning, using a stir plate creates more yeast slurry than not using one, every time.  This makes it easier to get to my desired pitch rate for a given beer style.
 

A stir plate does not allow one to exceed maximum cell density.  A stir plate does not provide much in the way of aeration when run at a speed low enough to prevent shear stress.  Any increase in yeast biomass is the result of cells that have kicked the bucket.  Continuous propagation overcomes the maximum cell density problem by continuously removing yeast cells.

 

Agreed, but a stir plate does help reach maximum cell density for a large starter (3-4L) in my experience, which is very helpful when making 10 gallons of lager or high gravity ale.

Quote
Quote
  The yeast is viable after staining.  The beer is happy. 

Please post microscope photo a methylene blue stained slide of your yeast. 

I'll do that after my next starter, as long as I can get my cell phone camera to cooperate with my student microscope's eyepiece.
Title: Re: Yeast propagation at White Labs
Post by: denny on June 18, 2015, 09:26:25 am
I hope that everyone who took the White Labs tour noticed the big orbital shaker table in the propagation lab.  I did not see a single stir plate in use at White Labs.

I'll stop using mine as soon as I get a big orbital shaker table!  In the meanwhile, I've proven to myself that a stir plate works better and faster than any other method I've tried.

So, get a stir plate?

Got one and use it every time I make a starter.
Title: Re: Yeast propagation at White Labs
Post by: denny on June 18, 2015, 09:30:14 am
So, get a stir plate?

You do not need waste money on a stir plate.  Do yourself a favor search the forum using the terms "shaken, not stirred" and "James Bond Method."  You probably already own everything that you need to make a healthy starter using this method.

Fortunately, one was given to me, so no money wast wasted.  And I still can't reconcile my personal results with your "best practices".  My own experience is that using a stir plate and decanting produces better beer at my house than shaking the starter and pitching at high krausen.  I respect the science, but I must be in some sort of Bermuda Triangle of non-science since it doesn't work like that for me.
Title: Re: Yeast propagation at White Labs
Post by: mchrispen on June 18, 2015, 10:21:45 am
I am actually working on a blog article looking at this. A friend spent the big bucks on an orbital shaker table some time ago. I have a stir plate. Planning to pressure cook wort and the stir plate, shaker table and shake method and do some viability and counting, fermentation with split batch wort. I may try to weave in a dry v rehydrated version as well... but with very rough manufacturer cell estimates in dry yeast, not sure it would be valid.

In the "Selecting Yeast Based on Strain.... yada longest seminar name ever" Kevin Lane said their pitching rates were based on biomass (dry weight) and not cell counts, advice that follows closely with Mark's recommendations. They are also adjusting their viability recommendations quite a bit. I was pretty surprised frankly... it's a large shift from the White Labs and Wyeast advice, but it was also seemed to be inferred that WL was propagating to mass in their new process and that the cell counts were significantly increased in their new process/packaging.

I was surprised in Kevin's advice on pitching dry and not rehydrated, but apparently they don't see in their labs the significant yeast die off from pitching into wort that others have reported. I "seem" to get better results with rehydration, but willing to admit personal bias. I spoke with him briefly after - he said the difference was really in lag times and not in ester/phenol expression. It was a bit boggling as I have done side by side tests with meads (1.100 gravity must) and the results were very different between 71B-1122 dry pitch and rehydration with GoFerm (as recommended by Schramm and Pietz), with the sugar break feedings.
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 18, 2015, 05:26:29 pm
I am actually working on a blog article looking at this. A friend spent the big bucks on an orbital shaker table some time ago. I have a stir plate. Planning to pressure cook wort and the stir plate, shaker table and shake method and do some viability and counting, fermentation with split batch wort. I may try to weave in a dry v rehydrated version as well... but with very rough manufacturer cell estimates in dry yeast, not sure it would be valid.

I was reading a paper on shaker tables last night.  One thing I found interesting was that the author claimed that the media volume should be no larger than 25% of the flask volume in order for the technique to be most effective.  This publication parallels my finding with well-shaken starters.  In the case of the shaker table, a media volume of 25% or less of the flask volume increases the surface area that is exposed to air.  My rationale for having at least that much extra volume is that it allows for expansion during shaking. Media (wort in this case), when expanded to foam, has significantly more surface area than media in pure liquid form.  I wonder how much more effective a stir plate spun at a slow enough speed to prevent shear stress would be if the media volume was limited to 10% of the flask volume.  Given two flasks of the same size with the same amount of media, the flask placed on the shaker table would have a larger amount of surface area than the flask placed on a stir plate due to the shaker table's orbital pattern causing the media to slosh up on to the sides of the flask.
Title: Re: Yeast propagation at White Labs
Post by: majorvices on June 19, 2015, 04:20:48 am
I have never noticed any negative effects from shearing when making starters on a stir plate and feel comfortable recommending that as a propagation technique.

I like the comment made by Narvin about "After trying their beers at the tasting room, I'm not sure I trust their palate on brewing advice." Similar experience on my end. Yeast biologists grow great yeast, and maltsters malt great malt and hop growers grow great hops but when I have tasted their beers I have not usually been very impressed. Leave the brewing to the brewers.
Title: Re: Yeast propagation at White Labs
Post by: toby on June 19, 2015, 07:30:45 am
I thought the point of the beers in the tasting room was to compare what different yeast strains do to the same base beer.  In that vein, the 'standard' yeast should be a good beer (which applied to the two flights I tasted), and then anything 'off' in the others is going to be the result of the interplay of the style with that yeast strain.  I get the impression they don't try to get complimentary flavors as much as highlight what the yeast does.  Some of those wind up making an interesting and different good beer, and some wind up being a train wreck.
Title: Re: Yeast propagation at White Labs
Post by: narvin on June 19, 2015, 07:32:50 am
I thought the point of the beers in the tasting room was to compare what different yeast strains do to the same base beer.  In that vein, the 'standard' yeast should be a good beer (which applied to the two flights I tasted), and then anything 'off' in the others is going to be the result of the interplay of the style with that yeast strain.  I get the impression they don't try to get complimentary flavors as much as highlight what the yeast does.  Some of those wind up making an interesting and different good beer, and some wind up being a train wreck.

Yes, but I didn't love the' standard' beer of any style.  The closest was the hefe with 300, but it still wasn't my favorite.
Title: Re: Yeast propagation at White Labs
Post by: mabrungard on June 19, 2015, 07:46:04 am
Keith, I haven't found detriment to my stirred starters since I typically stir slowly and use a 3" stir bar. But I don't doubt that a shaken vessel could be better than stirred. My point is that this appears to be a case of 'good and better'. Stir plates are still good and should be used, if you have one. Most of us won't have the opportunity to move up to a shaker like White Labs has.
Title: Re: Yeast propagation at White Labs
Post by: toby on June 19, 2015, 08:34:23 am
Yes, but I didn't love the' standard' beer of any style.  The closest was the hefe with 300, but it still wasn't my favorite.
I wouldn't expect to love any of their beers though.  I would just expect them to be middle of the road examples (something I would score in the mid-30s in a comp for example).  Their goal isn't to make beers I love.  It's to propagate and sell yeast.  They only have a tasting room to highlight what the yeast can do.
Title: Re: Yeast propagation at White Labs
Post by: narvin on June 19, 2015, 08:59:33 am
Yes, but I didn't love the' standard' beer of any style.  The closest was the hefe with 300, but it still wasn't my favorite.
I wouldn't expect to love any of their beers though.  I would just expect them to be middle of the road examples (something I would score in the mid-30s in a comp for example).  Their goal isn't to make beers I love.  It's to propagate and sell yeast.  They only have a tasting room to highlight what the yeast can do.

Agreed.  I wasn't necessarily disappointed since the comparison was interesting, but I wouldn't follow their brewer's advice for making beer above all others.
Title: Re: Yeast propagation at White Labs
Post by: hopfenundmalz on June 19, 2015, 09:04:29 am
When I got my stir plate, a friend in the club gave me some stir bars that have a "raised ring" in the center that the bar rotates on. He said that those were easier in the yeast than a flat stir bar.

Any thoughts?
Title: Re: Yeast propagation at White Labs
Post by: Joe Sr. on June 19, 2015, 09:21:54 am
So, get a stir plate?

You do not need waste money on a stir plate.  Do yourself a favor search the forum using the terms "shaken, not stirred" and "James Bond Method."  You probably already own everything that you need to make a healthy starter using this method.

Fortunately, one was given to me, so no money wast wasted.  And I still can't reconcile my personal results with your "best practices".  My own experience is that using a stir plate and decanting produces better beer at my house than shaking the starter and pitching at high krausen.  I respect the science, but I must be in some sort of Bermuda Triangle of non-science since it doesn't work like that for me.

You two need to agree to disagree and stop arguing about stir plates.  You're going to drive me mad.

Personally, I like my stir plates.  I think they've helped me to improve my pitching rates.  But do whatever works for you. 

People get too dogmatic about things sometimes.  There is more than one route to the production of great homebrew, and that's one of the great things about the hobby.

I'll do it my way, you do it your way.
Title: Re: Yeast propagation at White Labs
Post by: denny on June 19, 2015, 09:25:13 am
When I got my stir plate, a friend in the club gave me some stir bars that have a "raised ring" in the center that the bar rotates on. He said that those were easier in the yeast than a flat stir bar.

Any thoughts?

Don't know if they are or not, but that's what I use.  I also use a gal. jug for my container, so I'm at least somewhere in the ballpark of Mark's comment about limiting wort size.
Title: Re: Yeast propagation at White Labs
Post by: erockrph on June 22, 2015, 09:28:46 pm
I have never used a stir plate, so I cannot comment on their effectiveness or detriment, but I can say that they are absolutely not necessary. I have always followed the "shake it whenever you walk by it" method of aerating starters, and it has always worked fine. I did notice a big improvement when I started using the "Shaken, not stirred" method of starter aeration. My starters have taken off more rapidly, smell better (I take this as a subjective sign of yeast health), and have noticeably shorter lag times when pitched.

I'm not saying that everyone needs to toss their stir plate, but it is by no means a required piece of equipment. Your money is much better spent on a temp controller, a new keg, a sack of grain, etc. - unless you're a gadget addict and just want one for the fun of it.
Title: Re: Yeast propagation at White Labs
Post by: denny on June 23, 2015, 09:32:29 am
I have never used a stir plate, so I cannot comment on their effectiveness or detriment, but I can say that they are absolutely not necessary. I have always followed the "shake it whenever you walk by it" method of aerating starters, and it has always worked fine. I did notice a big improvement when I started using the "Shaken, not stirred" method of starter aeration. My starters have taken off more rapidly, smell better (I take this as a subjective sign of yeast health), and have noticeably shorter lag times when pitched.

I'm not saying that everyone needs to toss their stir plate, but it is by no means a required piece of equipment. Your money is much better spent on a temp controller, a new keg, a sack of grain, etc. - unless you're a gadget addict and just want one for the fun of it.

I don't think anyone was implying that you have to have a stir plate (or shaker table!).  I know I certainly wasn't.  I did the shake thing for years and it worked fine.  I've found that a stir plate lets me make starters in a shorter period of time, but I still wouldn't have one of someone hadn't given me an old one.
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 23, 2015, 09:19:21 pm
I did notice a big improvement when I started using the "Shaken, not stirred" method of starter aeration. My starters have taken off more rapidly, smell better (I take this as a subjective sign of yeast health), and have noticeably shorter lag times when pitched.

There's nothing magical about my method. It's just a low cost, low-tech way to dissolve O2 into wort that's based on physics.  Wort in foam form has a huge amount of surface area compared to wort in liquid form.  Foam maximizes the gas to liquid interface because gas-liquid foams have a very high specific surface area.  The yeast analogy of Denny's claim that malt wants to become beer is yeast cells want to multiply if given O2, carbon, and room to multiply. 
Title: Re: Yeast propagation at White Labs
Post by: majorvices on June 24, 2015, 04:11:02 am
Keith, I haven't found detriment to my stirred starters since I typically stir slowly and use a 3" stir bar. But I don't doubt that a shaken vessel could be better than stirred. My point is that this appears to be a case of 'good and better'. Stir plates are still good and should be used, if you have one. Most of us won't have the opportunity to move up to a shaker like White Labs has.

No disagreement from me. I don't use a stir plate very often any longer but I can honestly say that it improved the quality of my homebrew over standard starters. I also have great, perhaps better, luck with constant aeration starters. I'm sure a shaker table is the best of both worlds, and from a lab perspective Mark is absolutely correct. But from a practical perspective he is way off the mark. It's like telling someone they can't get to work in their Honda Civic because a BMW435i is the preferred method by Car and Driver magazine.
Title: Re: Yeast propagation at White Labs
Post by: S. cerevisiae on June 24, 2015, 10:51:06 am
I stand by my assertion that a stir plate is an unnecessary expense that most modern home brewers are led to believe is a necessary expense.  Agitation does not buy much with most brewing strains because they are NewFlo strains.  The keys to healthy growth are adequate O2 and carbon.
Title: Re: Yeast propagation at White Labs
Post by: denny on June 24, 2015, 11:01:48 am
I stand by my assertion that a stir plate is an unnecessary expense that most modern home brewers are led to believe is a necessary expense.  Agitation does not buy much with most brewing strains because they are NewFlo strains.  The keys to healthy growth are adequate O2 and carbon.

My stir plate was free.  And it does a demonstrably better job for me than just shaking the jug when I go by.