Just say "no" to yeast rinsing (a.k.a. yeast washing in amatuer brewer terms)

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I had never thought about freezing the wort before @Hanglow , that's genius. Could you give a little more detail? When to sterilise, how do you defrost etc.

This has been an interesting thread as I have started looking into reusing/ranching yeast and a more reliable way to start brews and minimise some variables at my disposal without spending £xxx on equipment.
I too am looking at using the data from Kai Troester that is compiled into brewers friend calculator for a yeast starter, which happens to use a stirrer. I just like the way it has tried to approach it with a small amount of predictability (using the grams of sugar to cell growth), which means I don't need to dive too deep into cell culturing.

Interesting about shear stress though, I will definitely be opting for a cylindrical stirrer and at a speed just enough to ensure mixing of the air and the wort.

Being a chemist, I love any excuse for a stirring plate :laugh8:, but I do like the simplicity of a "Shake n Bake" approach. I say if they are both achieving the same quality of beer, that the brewer enjoys, then let em have at it. I am glad to have come across this though and feel both methods should be side by side in books for the homebrewer to choose
 
@Burtsbeets Just make your recipe 1l larger than you want, and put that extra litre in a freezable container. Ice cream containers are good. When you want to make a starter for your next beer, defrost the wort (sometimes I don't defrost, just put the icey wort into the pan and heat) and bring to a boil. Cool quickly - I place the pan in a sink with cold water and ice, and move the pan about to cool it quick to about 20c, should only take about ten minutes or so. Then shake and make your starter.
 
I started harvesting yeast about 3 years ago primarily to save money but then discovered other benefits as well. All the beers that I pitched with harvested yeast took off quicker, finished sooner and with better attenuation. Good times all round.

Initially these repitches were with unwashed slurry but I found that when I used washed yeast in later batches that fermentation was slower to take off and the beers took longer to ferment out and also finished with a slightly lower ADF. I thought this might be that because they were later generations of the same yeast, the yeast had gotten ‘tired’. However, when I used a later generation of unwashed slurry harvested from a beer made with the washed yeast, fermentation went back to taking off quicker and was faster to reach terminal gravity and again the ADF improved. It’s for this reason that I don’t wash harvested yeast any more.

I recently made a beer with the slurry of a 21st generation of a Mangrove Jack’s M44 yeast and it fermented down to 1.010 from an OG of 1.045 in three days. The airlock was bubbling away a few hours after pitching and the finished beer is clean tasting with the clarity that I’ve come to expect from this yeast.
 
But White Labs themselves recommend the use of a stir plate for making yeast starters...



I find it hard to believe that they would be sucked into perpetuating a homebrew myth if there were not some evidence to support it


First off, the information on Kai's site needs to be viewed with the same skeptical eye with which many forum members are viewing my information. While some of the information is very good, some of it is also incorrect to the point of being very bad practice. For example, the way Kai demonstrates making plates is completely wrong. One never processes plates in a pressure cooker/autoclave. That is surefire way to make plates that are mold factories, especially in a home brewing lab. The correct way to pour plates is to dry sterilize the glass petri dishes in an oven at 170C for an hour. The media is placed in a covered glass container and processed in pressure cooker/autoclave at 15psi for 15 minutes and allowed to cool to between 49 and 60C before carefully lifting one side of the lid on a petri dish up only far enough to be able to pour enough agar-based media to cover the bottom of the dish before putting the cover back down. This technique works with pre-sterilized plastic plates as well. It results in significantly less condensation forming on the lids of the petri dishes. The condensation is insignificant enough that it will evaporate during proofing. Why did Kai not know that before writing his article? While Kai is clearly a very bright guy, it kind of calls into question his microbiology cred.

The White Labs video confounds me as well because it is not a practice White Labs uses in-house. White Labs does not use stir plates for in-house culturing. They use a sizeable multi-level orbital shaker in their main starter propagation room with shaker flasks. Shaker flasks resemble Erlenmeyer flasks, but they have baffles in the bottom to create turbulence and are usually squatter to improve air/liquid specific surface area. Some people use Erlenmeyer flasks with an orbital shaker, but the correct piece of lab glassware is the shaker flask. The funny thing is that Chris White stated that amateur brewers tend to be way too wrapped around the axle with respect to cell counts when I discussed the use of stir plates and yeast in general with him at NHC San Diego in 2015.

The reality is that no matter what is claimed a culture cannot exceed maximum cell density per ml because yeast cultures are self limiting. We are talking about viable in cells when we are discussing maximum cell density. If a starter reaches high krausen (i.e., a solid head forms on it) before it exhausts the carbon sources in the wort (sugar is carbon bound to water), it can be assumed to have reached maximum cell density for the volume of wort in the starter because high krausen occurs when a yeast culture reaches maximum cell density (i.e., high krausen marks the end of the exponential growth phase). Maximum cell density is based on actual yeast cell size (some yeast cells are larger than others), but a general rule of thumb is 200 million cells per ml, which means that a 1L starter that reaches high krausen can be assumed to have 200 billion cells. If we pitch the entire starter at high krausen into 23L of work, we end up with 24L of wort. If that bothers people, then they should concentrate their wort enough to allow for the dilution because pitching at high krausen results in a significant reduction in lag time, which is part of the secret sauce of SNS. Pitching the entire contents of a starter does not bother me, and I only pitch into 20L of wort most of the time, so the dilution is greater. I just adjust for it by having a slightly higher end of boil gravity than my target original gavity.

Now, getting back to our 200 billion cells in what is now 24L of wort. That number of cells yields a cell density of 200,000,000,000 / 24000 = ~8.33 million cells per milliliter. Using George Fix's rule of thumb that one should pitch 750,000 cells per ml of wort per degree Plato, 8.33 million cells per milliliter is good enough to pitch 8.33 / 0.75 = 11.11 Plato (~1.045 S.G.). However, in practice, a 1L starter pitched at high krausen will handle worts up to 16 Plato (1.065) with ease, that is, as long as we have a sound wort aeration.

With that said, we have to be more careful with high gravity wort because of two things; namely, much higher osmotic pressure and the increased difficulty of dissolving O2; therefore, affecting plasma cell membrane health if too much exponential growth is required to reach maximum cell density for a batch or wort. Higher gravity wort has a lower O2 saturation threshold for any given temperature than lower gravity wort, which means that we cannot support as much healthy cell growth. Osmotic pressure is phenomenon where water is drawn to the side of a semi-permeable membrane (the yeast cell cell plasma membrane in this case) with the highest solute content. Wort can be thought of as a solvent (water) and a solute (malt sugars) that is dissolved into the solvent. The solute on the wort side of the cell wall is much higher than it is inside of the cell, which results in water being drawn out of the cells, leading to the loss of cell membrane turgor pressure, which, in turn, results in cell shrinkage and wrinkling, and if taken to an extreme, cell implosion. There is also the additional threat posed to the culture by the higher alcohol levels found in high gravity beers. The page shown below is from page 220 in an article entitled "The Effects of Osmotic Pressure and Ethanol on Yeast Viability" in an issue of the Journal of the Institute of Brewing.

4k4QkEv.jpg

The image on the bottom left is what lager yeast cells look like when subjected to a 20% w/v (an S.G. of 1.083) sorbitol solution. As one can see, the cells have indentations from the loss of turgor pressure. The image on the right is what happens after yeast cells are exposed to 10% ethanol.

For the forum member who wants a detailed explanation of the SNS method, here is a link to the original SNS post I made on Jim's Beer Kit back in 2015: Shaken, not Strirred - Home Brew Forum

For those who want cell counts with respect to SNS, once again, SNS is about the fact that yeast cultures do not need to be spun, they need dissolved O2 at the time of pitching. SNS is based on a physical property of foam that allows one to diffuse a significant amount O2 into wort in a low-tech way coupled with two rules of thumb; namely, the maximum cell density for a 1L starter can be assumed to be 200 billion cells and pitching at high krausen results in optimal use of the ergosterol and unsaturated fatty acids (UFA) reserves that were built by the mother cells that were alive during a starter's lag phase. By pitching at high krausen, we avoid wasting ergosterol on replacement-only replication (remember, yeast cultures are self-limiting; therefore, they only replicate to replace cells that have died after maximum cell density has been reached). That is what occurs if we allow a starter to ferment past high krausen, and that is what most people who are using stir plates are doing. They are wasting ergosterol and UFA reserves that will need to be replenished when the culture is pitched into wort, driving up dissolved O2 demand. Not only that, allowing a starter for ferment out results in morphological changes that need to be reversed during the lag phase, which, in turn, lengthens the lag phase.

In the end, people are going to believe what they want to believe. Nothing I write is going to convince anyone with a closed mind. It does not bother me. I have been swimming upstream for quite a while and I only stand my ground when I know I am right. The shear number of people who have tried SNS and either parked or gave away their stir plates is evidence enough that the method is based sound principles. I stand on my belief that yeast calculators attempt to impose precision where none exists. Rules of thumb are good starting points, but only experience with a culture in one’s brewery teaches one what is needed. Like most breweries, I never pitch high gravity wort with a starter. I always use slurry harvested from a healthy standard gravity batch. A yeast culture almost always performs better on a second or third pitch than it does on the first pitch. That is what is known as a brewery best practice.
 
I absolutely have an open mind and change it when i see data. You saying 'closed mind' is what apologists do to try to undermine people that have genuine questions when they've got nothing, and it's a weakness, and an ugly one. I'm a big fan of rehydration of dry yeast; wasn't intially but then I saw experimental data that was beyond compelling. You can spout theory all you like but until there are experiments to back it up the model it's just wishful thinking.

Did you come up with shaken not stirred? Is this your baby and you want it to become a legacy? Do you want to have some impact on the brewing world? Are you in need of validation? Then get some data.

When college kids were still in school I heard about some people getting stuff like this tested for a crate of beer. Not going to happen for a while.

We'll all give you your ticker tape parade when it's all a bit more than "Well my friend Billy says..." And I mean this. If this is a great method I will scramble to the top of the flagpole and scream it to the stars.... when there's reason to do it.
 
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Yes, SNS is my creation and no, I am not looking for validation. I kept it to myself for two decades before presenting it as a option for making starters. Trust me, it was met with a lot more resistance than you are giving me. However, one by one, people tried it and adopted. I was away from the hobby from the summer of 2016 until the summer of 2020, so it was not me who was pimping SNS. It was people who tried the method and found it to be simple and effective. In fact, I was blown away by the extent my method had been adopted. I could care less if you are anyone else adopts my method. I have nothing to gain by it. I have had a successful career in my chosen profession. Addtionally, you can talk about the "minds being closed" as an argument used by people with a weak argument. However, that is a BS argument used by people with closed minds. When I came back to the hobby in 2013 after being away for several years, I did not cry foul by the number of people who claimed that stir plates where the greatest thing since sliced bread. I went along with the narrative until my results with stir plate did not match the claims. I went back to my old method which was simpler and more effective. My only dog in this fight is my desire to save people money by not purchasing a "not needed" piece of equipment that was not designed for cell culture. No one question the people who claim that stir plates are superior to all other methods, but their controls in their experiments are weak. A 1L starter that is periodically shaken in a 2L flask is not going to perform like a 1L starter that is originally shaken into foam in a 4L container.

I will leave you with this challenge. If you try my method and you do not see equal or better results, I will go away and never post to this forum again. Until then, you need to be quiet and act like you have functioning gray matter. You, my friend, come across as a paper tiger.
 
...snip... My only dog in this fight is my desire to save people money by not purchasing a "not needed" piece of equipment that was not designed for cell culture. No one question the people who claim that stir plates are superior to all other methods, but their controls in their experiments are weak. A 1L starter that is periodically shaken in a 2L flask is not going to perform like a 1L starter that is originally shaken into foam in a 4L container.

I will leave you with this challenge. If you try my method and you do not see equal or better results, I will go away and never post to this forum again. Until then, you need to be quiet and act like you have functioning gray matter. You, my friend, come across as a paper tiger.
If someone was just starting out and wanted to use liquid yeast instead of dried then I'd suggest they try your method since it doesn't require kit beyond a demijohn, I may give it a try as it would be a simple way to go from collected slurry from a batch to a pitch for the next one. Despite having a conical for 2 years I've yet to harvest from a batch as it's just been easier to overbuild starters, mostly because I can track cell count better. Even if the calcs on absolute counts are off they at least provide me with a repeatable method for starters and my beers ferment as expected. I found this thread where you said much the same as here and the idea of consistent biomass was interesting; 50 ml of slurry in a SNS starter for a typical batch is a pretty easy starting point. Although I was amused at the difference in the other members' response to your comments between here and there. :-)

However, criticizing other peoples experiments when you have only anecdotal evidence of your own procedure is a bit cheap. You're only real "data" is that the beer ferments out fine, which they generally do with stirred starters too, so this is a handy way to build starters without a stirplate, but it's not necessary "better" than a stir plate. The issue here is that your argument is coming across more like "get rid of your stirplate and do things my way because insert wall of microbiology says so" rather than, "hey, I've been doing starters this way, it works pretty well and doesn't need a stirplate, give it a try if you fancy." That way you wouldn't have had a few of us challenging your opinion because you wouldn't have been trying to prove a point (or appearing like it while shifting the burden of proof on to us).
 
I know it's not scientific, and there isn't any data... but I've just come across this about 1:17:15 in

 
Exactly @Zephyr259. I stumbled across the SNS back in 2015 and adopted it as I had a freshly emptied, clean and sanitised 5L Ashbeck Spring Water, bottle that had previously contained Starsan solution. The beer came out fine. Thoughts of sourcing or building a stir plate became redundant soon after.

Equally, had I a stir plate, I'd likely of continued using it if I was happy with my beers.
 
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I have perhaps gone the other way on this. I started with the SNS method after reading about it elsewhere and and was happy with it, however after a while I built a stir plate (possibly because I believed the hype) and have been using it since.

That might be surprising to the OP but I'll explain why. For me, and I suspect I'm not alone in this, what concerns me most of all is 1) which method will produce the best/most reliable results, and 2) which method is easiest.

Did I notice any increase in quality when I moved from SNS to stir plate? Nope. But I also didn't notice any drop in quality either. Which brings me to the second point, and I don't think I can say the SNS method is any easier. I boil and chill the starter wort in an Erlenmyer flask, add the yeast, and put it on the stir plate. It could be argued that this is easier because there's no need to sanitise a second container. Obviously the time taken to build the stir plate (~30 mins) and the cost of parts (<£10) would need to be factored in too, and for someone who doesn't have a stir plate I would happily recommend your SNS method.

@saccharomyces, going back to the theory though, much of your argument is based on the assumption that a starter on a stir plate will be completely fermented out, which of course is counterproductive. But what if the stirred starter was instead pitched at high krausen as you recommended in your SNS method? I know you mention other negative effects of the stir plate such as shear stress, but in a gently stirred starter what effect will this have in practical terms?

These are genuine questions by the way, I'm not being obtuse and I really appreciate you taking the time to post. I for one wish there were more of these technical posts on the forum :hat:
 
Contrary to what proponents of stir plates say, a yeast culture does not need to be stirred in order for the cells to remain in suspension. Most brewing strains exhibit what is known as the NewFlo phenotype, which means that the cells will remain in suspension as long as there are sugars that inhibit the flocculin coating (the yeast equivalent of Velcro) on a yeast cell wall from binding to other yeast cells (a.k.a. flocculation). Do you not find it to be curious that the stiring cultures is promoted by amateur brewers, yet, no mention is ever made about stirring wort? That is because it is yet another example of non-science-based amatuer brewing dogma. If you to understand why stir plates are a waste of money, please read my blog entry entitled "Shaken, not Stirred: The Stir Plate Myth Buster" (Shaken, not Stirred: The Stir Plate Myth Buster | Experimental Homebrewing).
My experience in the matter is that to make yeast its faster with a stir plate. I made one. Use it to make more yeast. Also when I pitch said yeast theres reduced lag time for the fermentation to begin. I would never stir beer in the bucket. No need to introduce o2 there. But for a nice yeast culture, why not?
 
I imagine both ways work well and any difference would not be noticeable on a homebrew scale. Anyone testing the two methods would need to use wort from the same batch and ferment under the same conditions, then a difference may be detectable.

When I use liquid yeasts I use a stir plate as this is what I was led to believe was best. @saccharomyces is obviously very passionate about about SNS method and has a lot of compelling arguments for it but like others have pointed out there is no data to back it up which I am curious about... getting cell counts done on a number of different starters prepared under the same conditions with the 2 different methods would actually be fairly easy to do and would go a long way to validating the theory, it would also be quite interesting - so with so much passion for the method and having spent a lot of time to argue for it why not also spend the time to back it up?

If shown to be better I would change but for now all the calculators online favour the stir plate method for cell count and Im not going to try and make my own calculator (with no data to use for any of the calculations).
 
I was on looking at stir plates and stumbled across this thread 🤨
Up until this point I have been making my starter in a pot on the hob, adding it to my 3 litre flask. Chilling in the sink then pitching my liquid yeast.
I would give it a good swirl every time I passed it. Decant then pitch normally 2 to 3 days later.
I would then use the slurry from that batch to brew my next. Normally stepping the abv up. So my last brew was a Czech pilsner using wyeast 2278. I used 1/3 of that yeast cake on a doppelbock.
Next will be WLP 530 for a Belgian single then use the yeast cake for a triple.
So back to the question stir or not to stir. I am lost 😢
 
So back to the question stir or not to stir. I am lost 😢
I think that the conclusion would have to be theory unproven due to the lack of laboratory quality data but there is a very strong logical science based argument to say that continuous stirring is not a good idea and may actually be detrimental.
Personally I plan to give the shake method using a large jar a try and see if it works for me.
I have a stir plate but it won't bother me if it becomes redundant.
Contributors have been complaining about the lack of data but real qualitative data is very hard to come by. It's not just cell count it's also about cell health and possibley other factors too. Would probably make a good final year project on a BSc brewing degree course perhaps, but it would not be a trivial exercise to do it properly.
I think that this has been a very interesting thread overall, lots of food for thought & experiment. I might even get round to reading that book on yeast that I have on my bookshelf!
 
I think that the conclusion would have to be theory unproven due to the lack of laboratory quality data but there is a very strong logical science based argument to say that continuous stirring is not a good idea and may actually be detrimental.
Personally I plan to give the shake method using a large jar a try and see if it works for me.
I have a stir plate but it won't bother me if it becomes redundant.
Contributors have been complaining about the lack of data but real qualitative data is very hard to come by. It's not just cell count it's also about cell health and possibley other factors too. Would probably make a good final year project on a BSc brewing degree course perhaps, but it would not be a trivial exercise to do it properly.
I think that this has been a very interesting thread overall, lots of food for thought & experiment. I might even get round to reading that book on yeast that I have on my bookshelf!
All very true points, I think at homebrew level we'd have to measure things like lag times and how close the main batch gets to it's limit of attenuation via a fast ferment test, but it's not as straightforward a thing to provide evidence for as other things.

The Yeast book is a good read, I've not read Malt, but think it's mostly focused on malting which isn't so helpful for homebrewers, of the other 3 Yeast was my favourite from science and readability points of view.
 

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