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Author Topic: Shaken, not Stirred: The Stir Plate Myth Buster  (Read 15019 times)

Offline BaseWerks Brewing

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #45 on: September 23, 2020, 12:04:40 pm »
Quote
Quote from: Saccharomyces on September 19, 2020, 12:35:32 PM
Quote from: denny 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.

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.

So your telling me the night before a brew day I can make a 1.5 qt starter in a 1 gallon jug, shake in up really well, pitch 1 packet of yeast, then mix it up a bit more before setting it on the counter.  The next day I can brew a 10 gallon batch of a moderate strength beer and just pitch that 1.5 qt (~1500ml) starter and I'll be good to go? No matter if its a ale or a lager? Here I'm making 3000ml starters with a stir plate days before and decanting down before pitching.   Consider my mind blown.

Anything else I need to be aware of?  Need to use 02 before pitching it into the beer?  Would this be the same for 2nd generation yeast that was harvested a few weeks/month ago and stored in the fridge?

I have the yeast book that is pretty common place with homebrewers.  I have notes from that describing if you let the starter sit past high krausen it allows the yeast to store up glycogen reserves and I was thinking that was a good thing.  Forgive me if that has already be explained but I start getting lost when it comes to microbiology.
Andy K
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Offline Kevin

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #46 on: September 23, 2020, 12:40:36 pm »


So your telling me the night before a brew day I can make a 1.5 qt starter in a 1 gallon jug, shake in up really well, pitch 1 packet of yeast, then mix it up a bit more before setting it on the counter.  The next day I can brew a 10 gallon batch of a moderate strength beer and just pitch that 1.5 qt (~1500ml) starter and I'll be good to go? No matter if its a ale or a lager? Here I'm making 3000ml starters with a stir plate days before and decanting down before pitching.   Consider my mind blown.

Anything else I need to be aware of?  Need to use 02 before pitching it into the beer?  Would this be the same for 2nd generation yeast that was harvested a few weeks/month ago and stored in the fridge?

I have the yeast book that is pretty common place with homebrewers.  I have notes from that describing if you let the starter sit past high krausen it allows the yeast to store up glycogen reserves and I was thinking that was a good thing.  Forgive me if that has already be explained but I start getting lost when it comes to microbiology.

I'm pretty sure you can make your SNS starter the morning of brew day. That's what I have been doing for the past couple years.
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Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #47 on: September 23, 2020, 01:47:54 pm »


So your telling me the night before a brew day I can make a 1.5 qt starter in a 1 gallon jug, shake in up really well, pitch 1 packet of yeast, then mix it up a bit more before setting it on the counter.  The next day I can brew a 10 gallon batch of a moderate strength beer and just pitch that 1.5 qt (~1500ml) starter and I'll be good to go? No matter if its a ale or a lager? Here I'm making 3000ml starters with a stir plate days before and decanting down before pitching.   Consider my mind blown.

Anything else I need to be aware of?  Need to use 02 before pitching it into the beer?  Would this be the same for 2nd generation yeast that was harvested a few weeks/month ago and stored in the fridge?

I have the yeast book that is pretty common place with homebrewers.  I have notes from that describing if you let the starter sit past high krausen it allows the yeast to store up glycogen reserves and I was thinking that was a good thing.  Forgive me if that has already be explained but I start getting lost when it comes to microbiology.

I'm pretty sure you can make your SNS starter the morning of brew day. That's what I have been doing for the past couple years.

As long as it's at high krausen
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Offline Saccharomyces

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #48 on: September 23, 2020, 02:43:52 pm »
So your telling me the night before a brew day I can make a 1.5 qt starter in a 1 gallon jug, shake in up really well, pitch 1 packet of yeast, then mix it up a bit more before setting it on the counter.  The next day I can brew a 10 gallon batch of a moderate strength beer and just pitch that 1.5 qt (~1500ml) starter and I'll be good to go? No matter if its a ale or a lager? Here I'm making 3000ml starters with a stir plate days before and decanting down before pitching.   Consider my mind blown.

Anything else I need to be aware of?  Need to use 02 before pitching it into the beer?  Would this be the same for 2nd generation yeast that was harvested a few weeks/month ago and stored in the fridge?

I have the yeast book that is pretty common place with homebrewers.  I have notes from that describing if you let the starter sit past high krausen it allows the yeast to store up glycogen reserves and I was thinking that was a good thing.  Forgive me if that has already be explained but I start getting lost when it comes to microbiology.

You cannot make a 1.5L SNS starter with a gallon jug because the container needs to be at least 4 times, preferably 5 times the volume of a the starter medium.  A 1.5L stater would require a minimum of a 6L bottle.  Additionally, there is literally no difference between a 1.5L and 1L starter (please throw your yeast calculator away).  The yeast cell count grows exponentially, not multiplicatively. The difference between a 1L and a 2L starter is one replication period.  Yeast cultures grow a rate of 2^N where, the symbol "^" denotes raised to the power of and N is the number of replication periods.  What this growth rate means to the layman is that cell count in the yeast biomass contains 1, 2, 4, 8, 16 ... times the initial cell count at time 0, end of replication period 1, end of replication period 2,  end of replication period 3, end of replication 4.   In effect, the cell count is doubling every replication period because a mother cell buds a daughter cell every replication period and a daughter cell that was budded during one replication period becomes a mother cell during the next replication period.

It is true that yeast cells store glycogen in preparation for quiescence, but they do so as a safeguard against starvation.  Yeast cells also undergo morphological changes in order to prepare for starvation that have to be undone before they can go about rebuilding ergosterol reserves, which are significantly more depleted if a culture is allowed to ferment beyond high krausen.  In effect, allowing a starter to ferment out results in longer lag times and higher initial O2 requirements.  You should read my blog, starting with "Yeast Cultures are Like Nuclear Weapons."  The URL is: https://www.experimentalbrew.com/blogs/saccharomyces (thanks goes to Denny and Drew for providing me a place to blog).  You need to double click the title of each blog entry to see the entire text.
« Last Edit: September 23, 2020, 04:24:59 pm by Saccharomyces »

Offline BaseWerks Brewing

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #49 on: September 23, 2020, 07:43:54 pm »
Quote
You should read my blog, starting with "Yeast Cultures are Like Nuclear Weapons."  The URL is: https://www.experimentalbrew.com/blogs/saccharomyces (thanks goes to Denny and Drew for providing me a place to blog).  You need to double click the title of each blog entry to see the entire text.

Mark, will do.  I would already have read it but ran out of time while on my lunch break  :D
Andy K
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Offline 4dogbrewer

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #50 on: September 24, 2020, 05:34:25 am »
High krausen, how will I know when that happens? How long does it last? What do I do when I am past high krausen?

Offline 4dogbrewer

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #51 on: September 24, 2020, 06:36:07 am »
Making a starter on brew will be a challenge for me. Kind of busy with mashing and heating water. What about the night before brew day?

Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #52 on: September 24, 2020, 08:26:02 am »
Making a starter on brew will be a challenge for me. Kind of busy with mashing and heating water. What about the night before brew day?

I do it 24 hours before.  I think that's optimal.
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Offline Richard

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #53 on: September 24, 2020, 10:22:25 am »
Making a starter on brew will be a challenge for me. Kind of busy with mashing and heating water. What about the night before brew day?

As Mark said, you can start it earlier the day before and after a few hours you can put it in the refrigerator overnight. The cool temperature will slow the growth and effectively delay the onset of high krausen. I tried it this week and it worked great. I call this technique SNS The Next Generation: PICARD (Pitched In Container And Refrigerator Delayed).
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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #54 on: September 24, 2020, 12:59:56 pm »
Making a starter on brew will be a challenge for me. Kind of busy with mashing and heating water. What about the night before brew day?

As Mark said, you can start it earlier the day before and after a few hours you can put it in the refrigerator overnight. The cool temperature will slow the growth and effectively delay the onset of high krausen. I tried it this week and it worked great. I call this technique SNS The Next Generation: PICARD (Pitched In Container And Refrigerator Delayed).

And, when you have a newborn, you really don't know when you're going to brew.  I put it in the fridge for what ended up being 10 days and just decanted all the old liquid off of it.  With 2 minutes of pure O2 in the wort, it took off like a rocket!  What's old is new again, eh?

Offline tommymorris

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #55 on: September 24, 2020, 01:48:27 pm »
I call this technique SNS The Next Generation: PICARD (Pitched In Container And Refrigerator Delayed).
Nice!

Offline BrewBama

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #56 on: September 24, 2020, 03:19:35 pm »
I call this technique SNS The Next Generation: PICARD (Pitched In Container And Refrigerator Delayed).
Nice!



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Offline Kevin

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #57 on: September 25, 2020, 08:03:39 am »
Making a starter on brew will be a challenge for me. Kind of busy with mashing and heating water. What about the night before brew day?

Make it while the water is heating.
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Offline Wilbur

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #58 on: September 25, 2020, 10:28:04 am »
Do you have any sources I can read that support your arguments against stir plates?

Here is a better question; namely, have you 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 an 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.

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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 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 it 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.

A few more posts since I last checked this out...

I think people should use whatever method works for them. I've done SNS and used a stirplate, and I tend to use my stirplate. I've got a newborn, so once it's started I don't have to swirl or do anything to release CO2 from solution. I think there's also a huge number of homebrewers who've successfully used a stirplate without creating a "foul smelling thing."

TLDR Version:
  • It truly doesn't matter how you manage your starter as long as you provide enough oxygen and remove CO2 periodically.
  • CO2 toxicity is real, and swirling by hand or stirring gently with a stir plate will increase growth
  • CO2 blanket doesn't apply when there is fluid (gas) movement.
  • A stir plate can absolutely add O2 to wort, until there's sufficient yeast activity/CO2 output from the wort that positive pressure is created in the vessel which limits O2 ingress (Airlock activity/lag is typically 4+ hours, high krausen in 12-18)
  • Flavor profiles of yeast are relatively consistent through a range of pitch rates (strain dependent), so if your starter is off "optimal" by a few M/ml it's going to be fine.
  • "If you're using a stir plate, shaking, or aeration, the yield will be higher" Yeast J. Zainasheff & Chris White


I'd also say it's unfair to say no testing or research has been done regarding starters at a homebrew level. Take a look at "Yeast" by Chris White & Jamil Zainasheff. Your claims of "foul smelling things" also fly against the experience of many homebrewers, who use stir plates without issues.

Carbon dioxide toxicity is something that is confirmed by science. This is commonly tested in a bioreactor, with oxygen continuously supplied. With this optimal setup, yeast growth and health is slightly inhibited when CO2 becomes greater than 40% of the solution, and significantly inhibited at concentrations above 50%. From data collected by Die_Beerery, you can see that yeast will consume 10 ppm of dissolved oxygen in an hour. It thus seems self evident that without regular agitation, yeast growth will be limited.

https://www.themodernbrewhouse.com/wort-study-1/
https://pubmed.ncbi.nlm.nih.gov/786407/

Quote
Our tests showed that vigorously shaking a starter every hour results in approximately double the number of cells created when using a starter that is not shaken.
Yeast Whit & Zainasheff

Quote
The yeast will do best when the starter setup continuously releases the carbon dioxide they reate, keeps them in suspension and evenly distributed throughout the solution, and provides them with access to reasonable amounts of oxygen.
Yeast White & Zainasheff

Carbon dioxide is heavier than air, but that's not relevant when there's moving fluid. It might factor in an environment like a cave where there's no air movement, but actively fermenting yeast puts out CO2. This would only limit oxygen intake if you have an airlock in place, or the positive pressure of carbon dioxide put off by the starter exceeds the atmostpheric pressure. High krausen is typically achieved in 12-18 hours (White & Zainasheff), and many beers see airlock activity in 4+ hours so I think it's safe to say that a starter will take up O2 from the atmosphere for a few hours after yeast is pitched.

Hopefully this was rambling and incoherent enough, I had to piece it together in between a dozen or so diaper changes.

Offline denny

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Re: Shaken, not Stirred: The Stir Plate Myth Buster
« Reply #59 on: September 25, 2020, 10:51:47 am »
Since Chris White has been brought into this, I'll quote what he said to me when I told him about the SNS method....."that's great!  Homebrewers are too hung up on numbers"
Life begins at 60.....1.060, that is!

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