Author Topic: Shaken, not Stirred: The Stir Plate Myth Buster  (Read 4850 times)

Online Saccharomyces

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #15 on: September 18, 2020, 08:39:04 pm »
Just casual observation, but I made a 10 gallon batch of lager (1.050 ish) that I pitched 2 separate SNS starters into.  A subsequent batch was pitched with just one 1 L SNS and it fermented out in roughly the same time frame as the 2 starter batch, certainly less than a days’ difference overall.  Just a couple data points and YMMV, of course.

That is because yeast cultures are like nuclear weapons in that close is good enough. :)

Offline jeffy

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #16 on: September 18, 2020, 09:22:27 pm »
I remember the very first AHA conference I went to in New Orleans in 1996.  A speaker there (she was either a lab person or a pro brewer) was making the claim that stir plate starters produce 4 times as much yeast as starters without a stir plate.  Of course that was along time ago, but that's what lead me to buy my first stir plate.
That was the same year that Larry Bell gave a talk about Eccentric beer and passed out a hand written page and a half list of all the ingredients including Levi Garrett chewing tobacco.  Good times.
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Offline narvin

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #17 on: September 18, 2020, 09:45:26 pm »
One question: I always shake my starters to aerate, but I noticed that the foam has little to no head retention unless I’m repitching yeast from a previous batch.  So when starting from a white labs pack, I can’t really get much foam in the jug.  I use canned starter wort (unhopped) that I make specifically for this, not DME.

The head falls fairly quickly do to the low gravity of the wort.  However, I can usually shake hard enough to transform around 500ml of wort into foam.  The starter in the photo in the blog entry contained 1L of starter wort before shaking. As one can see, the liquid line is near 500ml.

What I have noticed with British brewers is that they use ribbed 5L water bottles and get an amazing amount of foam.  The ribs are clearly causing turbulence that creates more foam that a straight-side container.

Interesting.  I may have to try a different container. When I throw in saved yeast from a previous batch, I can usually get a pretty good foam, possibly from some additional proteins from the beer or hops.  Without, I'm lucky if the foam is an inch or two in a 1 gallon jug.

Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #18 on: September 18, 2020, 10:13:55 pm »
Mark, I have a question...lately I've been brewing 12 gal. batches on the Grainfather G70.  I split them into 2 fermenters, 6 gal. each.  Is there any chance that a 1 qt. SNS starter could be split be split between the 2?  Theoretically, do you think it would work?  I have no problem giving it a go if you think it might be feasable.
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Offline Wilbur

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #19 on: September 18, 2020, 10:30:36 pm »
Do you have any sources I can read that support your arguments against stir plates?

Here is a better question; namely, have ever seen a stir plate mentioned in a published yeast research paper?  That is because a stir plate is not the correct device for cell culture.  The correct mechanical device is an orbital shaker.  That is what White Labs uses in the room where they grow seed cultures for propagation.   The use a stir plate in cell culture is amateur brewer creation that is based on an incomplete understanding of brewing yeast strains.  As I mentioned in my blog entry, brewing yeast strains do not need to be stirred to remain in suspension because they belong to the NewFlo phenotype and the claim that they can exceed maximum cell density is nonsense. Brewing yeast strains do not truly respire in wort above the Crabtree threshold, which causes overflow metabolism.  What they do is shunt O2 and carbon from the fermentative metabolic pathway to the respirative metabolic pathway for the production of ergosterol and unsaturated fatty acids (UFA) during the lag phase, the spinning the culture continuously adds O2 to the culture is based on not only not understanding how brewing yeast strains operate, it is based on faulty information because very little O2 is entering the flask after CO2 production occurs due to CO2 being heavier than air.   About the only beneficial thing spinning does is help to drive off CO2 gas.  Other than that, the downsides of a stir plate outweigh the upsides.

As far as to references, I have pieced a lot information together from various publications I have read over the years.  I did not cherry pick my information.  I continuously check for new research.  If you use the search term "brewers yeast respiration Crabtree." you will be rewarded with links to many publications.   

Here is one such link:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4429655/

The abstract from that publication.

"The capability to ferment sugars into ethanol is a key metabolic trait of yeasts. Crabtree-positive yeasts use fermentation even in the presence of oxygen, where they could, in principle, rely on the respiration pathway. This is surprising because fermentation has a much lower ATP yield than respiration (2 ATP vs. approximately 18 ATP per glucose). While genetic events in the evolution of the Crabtree effect have been identified, the selective advantages provided by this trait remain controversial. In this review we analyse explanations for the emergence of the Crabtree effect from an evolutionary and game-theoretical perspective. We argue that an increased rate of ATP production is likely the most important factor behind the emergence of the Crabtree effect."

Who ever made the claim that stir plates produce more yeast because they continuously aerate the culture knew nothing about how the Crabtree effect.

Quote
Isn't intense shaking also going to induce shear stress?

Yes, it will, which I noted in the blog entry.  As I mentioned, the starter can be pitched before or after shaking. If one pitches after shaking, it is best to gently shake the culture a second time to disperse the cells.

Quote
If you pitch the whole starter, then don't you usually pitch the early flocculating yeast anyway? Isn't pitching early flocculating yeast an issue with yeast cropping/sourcing?

I think that you are misreading into what I wrote or reading into it.  Both methods result in early flocculators.  The difference is that they are not held in suspension with an SNS starter.  The whole argument that a yeast culture needs to be spun to remain in suspension is demonstrates a lack of understanding of the NewFlo phenotype (you can Google that one too).

Quote
The last I feel often gets confounded, I feel I often read complaints against a particular method in hobbies when the method is independent of the end result. Is the primary issue using a stir plate, or pitching a starter that's fermented out? I typically use a stir plate but start my starter an hour or two before the brew day. When I'm done brewing, the starter is usually at high krausen and I pitch the whole thing.

It is primarily an issue of stir plates being promoted as the best way to make starters to new brewers, which is not based on peer-reviewed science.  It is based on amateur brewer dogma just a like the dogma of using a secondary fermentation vessel to avoid autolysis.  Luckily, the use of secondary fermentation vessels has died off.  My goal is to educate new and exiting brewers about the fallacy of promoting stir plates as the best way to make a starter because it is not backed up by science. The absolute best way to make a starter is to saturate the starter wort with an O2 bottle and a diffusion stone before the culture is pitched (pure O2 provides for a higher saturation level than air). However, that method imposes cost and the responsibility of keeping a diffusion stone sanitary.  As mentioned in the blog entry, my method of making a starter is not do all, be all method for making a starter.  What is is simple, low cost, and highly effective.  The proof is in the pudding that few of the people who have tried SNS after using a stir plate went back to using a stir plate.  Why would a brewer work harder than he/she needed to in order to achieve a comparable result?

By the way, I am not targeting you.  I expect to get heavy blow back from the blog entry.  People do not like to feel like they have been taken for a ride based on faulty information.
Targeting like this leads to more productive discussions about brewing. I'm not worried about it at all.

I've always understood stirring to be about removing carbon dioxide (shown to be toxic to yeast at high enough concentrations), at least after yeast starts reproducing. I'm also under the impression oxygen intake is limited by CO2 off gassing and creating a positive pressure effect, I believe CO2 being heavier than air is irrelevant when talking about moving gasses.

I don't have any beefs with SNS, I tend to use my stir plate to prevent blowoff with starters. It was also a gift, I probably wouldn't have spent any money on it either.

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Online Saccharomyces

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #20 on: September 19, 2020, 12:35:32 pm »
Mark, I have a question...lately I've been brewing 12 gal. batches on the Grainfather G70.  I split them into 2 fermenters, 6 gal. each.  Is there any chance that a 1 qt. SNS starter could be split be split between the 2?  Theoretically, do you think it would work?  I have no problem giving it a go if you think it might be feasable.

It should work for beers that are up to 1.060.   A lot of people used to pitch 500ml starters.  The only way to know for certain if it will achieve acceptable results for you is to try it.  I would be cautious with worts above 1.060, that is, unless you have access to an O2 bottle.  Higher osmotic pressure combined with increasing difficulty when it comes to dissolving O2 as gravity increases makes underpitching a risky endeavor.  High osmotic pressure leads to water being drawn out of the cells, which, in turn, causes a loss in turgor pressure.  Yeast cells without healthy cell walls and plasma membranes wrinkle and implode.

Offline mabrungard

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #21 on: September 19, 2020, 12:41:37 pm »
I like spinning and continuously aerating a starter to proof the yeast.  I do chill and decant the spent wort.  But then during chilled wort runoff, I run oxygenated wort into the beaker and give it some good shaking and let it get to work for a few hours before pitching. 
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Online Saccharomyces

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #22 on: September 19, 2020, 12:51:08 pm »
I remember the very first AHA conference I went to in New Orleans in 1996.  A speaker there (she was either a lab person or a pro brewer) was making the claim that stir plate starters produce 4 times as much yeast as starters without a stir plate.  Of course that was along time ago, but that's what lead me to buy my first stir plate.

Yes, that may have been the genesis of stir plate adoption, but it is based on faulty information.  That research did not include direct O2 injection. It did include periodic shaking, but not an intense initial shake in an oversized container to increase 02 absorption.  The periodic shaking was performed using an Erlenmeyer flask with not much in the way of headspace.  The focus was more on agitation than O2 absorption.  The one thing that we know for certain is that if a starter reaches high krausen, it has reached maximum cell density beyond which replication is for replacement only, which means that we can get an overall higher cell count in the sediment if we allow a starter to ferment beyond high krausen, but we cannot get get a higher viable cell count.  The liquid cultures that are being sold today are huge compared the liquid cultures that we used in the 90s.  Pitching a smack pack without a starter was pure lunacy because it resulted in lag times measured in days.  Very few sane people did it more than one time.  Today, a relatively new White Labs culture can be pitched into 5 gallons without a starter. That is because the cell count is so high.

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #23 on: September 19, 2020, 12:59:42 pm »
I like spinning and continuously aerating a starter to proof the yeast.  I do chill and decant the spent wort.  But then during chilled wort runoff, I run oxygenated wort into the beaker and give it some good shaking and let it get to work for a few hours before pitching.

The reality is that spinning is not necessary.  It adds absolutely no value because most brewing yeast strains do not need to be spun to stay in suspension because they belong to the NewFlo phenotype and the strains that are not NewFlo are Flo1. Now, adding O2 is on the money.

Offline Kevin

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #24 on: September 19, 2020, 01:51:40 pm »

... The proof is in the pudding that few of the people who have tried SNS after using a stir plate went back to using a stir plate.  Why would a brewer work harder than he/she needed to in order to achieve a comparable result?

Count me in that group. I stumbled upon a thread talking about the SNS method a little over a year ago and tried it. My stir plate has been on a back shelf gathering dust ever since.
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Offline chezteth

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #25 on: September 19, 2020, 02:08:08 pm »
I have used the SNS method with ales with great success. Now I'm curious about using this method with lagers.

If I brew a pilsner, how many packs of liquid yeast should I use in the 1 liter starter? Is one pack enough? Or, should I use 2 packs in the 1 liter starter? Or, should I make a larger starter with 2 packs?

Cheers,
Brandon

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Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #26 on: September 19, 2020, 02:38:40 pm »
Mark, I have a question...lately I've been brewing 12 gal. batches on the Grainfather G70.  I split them into 2 fermenters, 6 gal. each.  Is there any chance that a 1 qt. SNS starter could be split be split between the 2?  Theoretically, do you think it would work?  I have no problem giving it a go if you think it might be feasable.

It should work for beers that are up to 1.060.   A lot of people used to pitch 500ml starters.  The only way to know for certain if it will achieve acceptable results for you is to try it.  I would be cautious with worts above 1.060, that is, unless you have access to an O2 bottle.  Higher osmotic pressure combined with increasing difficulty when it comes to dissolving O2 as gravity increases makes underpitching a risky endeavor.  High osmotic pressure leads to water being drawn out of the cells, which, in turn, causes a loss in turgor pressure.  Yeast cells without healthy cell walls and plasma membranes wrinkle and implode.

Likely to be more like 1.065.  I'm gonna give it a go with WY1217.
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Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #27 on: September 19, 2020, 02:39:41 pm »
I like spinning and continuously aerating a starter to proof the yeast.  I do chill and decant the spent wort.  But then during chilled wort runoff, I run oxygenated wort into the beaker and give it some good shaking and let it get to work for a few hours before pitching.

Have you ever tried SNS to compare?  I feel like I get healthier yeast than when I used a stir plate.
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Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #28 on: September 19, 2020, 02:41:30 pm »
I have used the SNS method with ales with great success. Now I'm curious about using this method with lagers.

If I brew a pilsner, how many packs of liquid yeast should I use in the 1 liter starter? Is one pack enough? Or, should I use 2 packs in the 1 liter starter? Or, should I make a larger starter with 2 packs?

Cheers,
Brandon

Sent from my Pixel 2 XL using Tapatalk

I have made lagers with SNS many times.  One pack is enough.  When you talk about using more, you are falling into the cell count trap.
Life begins at 60.....1.060, that is!

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Online Saccharomyces

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #29 on: September 19, 2020, 03:17:38 pm »
I have made lagers with SNS many times.  One pack is enough.  When you talk about using more, you are falling into the cell count trap.

Brandon,

I will add to Denny’s comment by saying that yeast cell counts have been overblown in the amateur brewing community. I blame this phenomenon on the heavy use of brewing software. The yeast biomass grows exponentially at a rate of 2^n, where the symbol “^” denotes raised to the power of and n is the number of replication periods. Under optimal conditions the replication period is around 90 minutes. We usually use yeast below optimal growth temperature, which lengthens the replication period, but to drive this information home, the difference between 200B cells and 400B cells is one replication period. The difference between 200B cells and 800B cells is two replication periods. What matters is yeast cell health going into the fermentation and the amount of dissolved O2 in the wort.

If you would like to know more about this subject, read my blog entry entitled “Yeast Cultures are Like Nuclear Weapons” (https://www.experimentalbrew.com/blogs/saccharomyces/yeast-cultures-are-nuclear-weapons).
« Last Edit: September 20, 2020, 01:04:08 pm by Saccharomyces »