The cold hard truth about rinsing yeast with boiled water

[RonPopeil]

OK so i understand the argument here but what would the proposed new process be if slanting isn't possible.

My typical process is actually for new vials of yeast. I make a large volume (3-4L) started at an OG of ~1.030 and pitch an entire vial to it. Once it flocs out I decant the clear fluid and pitch another large volume at ~1.050 OG. From the calculators I've used this should be around 350B cells per pint. I decant half of this fluid once the yeast flocs and then agitate it back up before bottling in sanitized jars.

So in this process the yeast is stored in a remainder of the second starter wort within an ice tea bottle or spaghetti sauce jar which i've kept tightly sealed. Aside from freezing: Is there a better way?

 

[RonPopeil]

Let me see if I have this correct:

- If I want to harvest yeast after fermentation and I'm going to use it to ferment another batch within 1 month, I can just grab some of the slurry from the fermentor and store it in a fridge before reusing it in another batch.

- If I want to harvest yeast after fermentation and I'm NOT going to use it to ferment another batch within 1 month (and I don't want to do agar slants and freezing), I can just grab some of the slurry from the fermentor, but every month, I should basically make a starter with it and feed it fresh wort to keep it viable.

Is that correct??

yeah same questions. and at this point how do i keep track of cell counts and keep my pitch rates in order?

 

[mtnagel]

yeah same questions. and at this point how do i keep track of cell counts and keep my pitch rates in order?

You should still be able to use MrMalty's "repitching from slurry" calculator. The thing that gets me though is the thin to thick slurry slider. You can get wildly different answers when you move that from side to side and I really don't know how to judge what I have.

I once harvested the "slurry" from the fermentor and it was so thick it was almost a solid (I don't like to leave any beer behind when transferring ). It wouldn't pour that's for sure. Even moving it to "thick," I'm sure mine was more concentrated than that. Kind of hard to predict quantities in that case. But I've always heard it's better to over pitch than under pitch, so I just guesstimated. Beer came out great!

 

[drksky]

So, I'm reading the Maltose Falcons article and came across this:

If you plan on storing the yeast for more than a couple weeks, it is best to wash the yeast with some yeast after a day or two in the refrigerator.

Wash the yeast with some yeast? Is this a typo?

 

[Bearfoot]

yeah same questions. and at this point how do i keep track of cell counts and keep my pitch rates in order?

I found this thread quite helpful. Had to download a scientific calculator widget but it was worth it.

 

[RonPopeil]

I found this thread quite helpful. Had to download a scientific calculator widget but it was worth it.

Thanks I'm going to have to check that out!

 

[Bottoms_Up]

https://www.homebrewtalk.com/f163/yeast-washing-illustrated-41768/

Thank you. I have seen that but wasn't sure that was the one being talked about. There's another great video of yeast washing on Billy Broaz's site:

http://billybrew.com/yeast-washing

 

[Orthobrewsky]

Nowhere in the text do the authors state that yeast should be rinsed with boiled water before repitching.

That's true, but I think you are splitting hairs just a bit and it's a hair I've already split when I mentioned that they did recommend rinsing with "sterile" water before repitching. Yes, spores can survive boiling, but I guess they can probably survive fermentation as well and if you leave your pot uncovered at all while chilling, some may be slipping in. Also, if you are using the same water for brewing that you use for rinsing, it is likely to have the same initial concentration of spores in it before exposure to air. Thus, I would think that the concentration of spores in the rinsed sample is likely to be a bit less than the concentration in the sample harvested as you recommend, considering that the boiled water started out the same as the brewing water and had less exposure to air.

While boiled wort is not sterile, it has 5.2 pH, which helps to keep wild microflora at bay until the culture can lower the pH even further. Boiled tap water usually has pH 7.0 or higher. Replacing the green beer with boiled water raises the pH of the culture.

And, as you have pointed out, alcohol is far more hostile to most of our common contaminants than to yeast. Those are some issues certainly worthy of consideration. When pondering them it occurred to me that simple (as opposed to thorough) rinsing, as is described on some pages referenced in this thread, probably gives us a sample for storage which is about half beer, so the pH might still be pretty decent and there would be enough alcohol to do some good too. So, since I had an old sample in the frig resulting from a simple rinse, I decided to do some tests. The liquid sitting above the yeast read as follows:

5.1 pH
2.3% ABV (The beer was 4.6%)



That still sounds somewhat protective and the added water thinned out the cake, allowing me to more readily separate yeast from trub. Finished beer has somewhat lower pH and higher alcohol, but rinsing also lowers the concentration of potential food for wild organisms and then the sample goes straight to the frig. Those electing for a thorough rinse would leave wild bugs nothing to eat, while losing the buffering capacity of the beer. However, they could easily adjust pH as is done to a greater degree in actual washing.

I'm convinced your recommendation has merits and advantages, but I'm not convinced that rinsing with boiled water is a bad thing and it has its own advantages. I think that the data from some experiments should be brought to light before concluding emphatically that one method is better than the other.

By the way, if you want to read a real brewing yeast textbook, pick up a copy of Brewing Yeast and Fermentation by Christopher Boulton and David Quain.

That looks very nice and I put it on my Amazon wish list. For now, the $80 price tag causes me to hesitate, but I thank you for the recommendation.

 

[AnOldUR]

So, this is the wrong way?

1. Always make an effort to transfer as little as possible hop and break material into fermentor. Never dry hop in primary.

2. Cold Crash primary a few days after fermentation is complete using a slow temperature ramp up. The cold crashing aids in dropping some of the less flocculent yeast.

3. Carefully tilt cold carboy so that all but an ounce or so of beer can be siphoned from on top of the compact cake.

4. Rinse cake with refrigerated water that has been boiled to sanitize. Swirl and give it a short time to settle. Decant leaving as much non-yeast trub behind as possible.

5. Place cold slurry immediately in fridge to keep yeast in its dormant state.

Works every time for me . . . (avatar worthy )

 

[mtnagel]

That is an impressive amount of very clean looking yeast! Well done.

FYI, Halloween is over

 

[AnOldUR]

That is an impressive amount of very clean looking yeast! Well done.

Thanks. Fifth generation Pacman rinsed from two carboys. Seventh generation of the same yeast is now fermenting an IPA. It might be a little extra work at transfor, but the nice thing about a large, fresh slurry . . . no need no stinkin' starter on brewday. Pull yeast from fridge, decant water, add chilled wort, shake and pitch.

 

[EarlyAmateurZymurgist]

But again, the test would have to include repeated use, not just the first collection. For example, if you were to reuse the yeast slurry, say after 7 or 8 times in subsequent brews, one would expect a considerable amount of dead, weak and mutated yeast cells as an accumulation of all those collections. Don't forget that if all the slurry is collected each time, then it would contain almost ALL of the trub associated with every previous slurry. Thus any test should represent repeated use, not just the first slurry.

First off, one should not collect all of the solids in one's primary fermentation vessel. By leaving enough green beer in the primary fermentation vessel to be able to swirl the contents back into suspension, waiting a few minutes for the heaviest fraction to settle out, and decanting the lightest fraction, one is almost guaranteed to collect mostly viable yeast cells while leaving behind most of the break and the dead yeast cells because dead yeast cells drop out suspension quickly. By not overpitching, we are guaranteed to have healthy ratio of live to dead cells. We can restore the vitality of a non-infected culture by underpitching and oxygenating,

The major elephant in the room with respect to repitching is contamination by house microflora. The primary reason why breweries limit repitching is due to cumulative contamination by wild microflora. Very few liquid cultures are 100% contamination free. House microflora can have an significant impact on flavor and performance. Most infections are pitched with the culture.

 

[EarlyAmateurZymurgist]

5. Place slurry immediately in fridge to keep yeast in its dormant state.

Yeast doesn't go dormant when stored under boiled tap water. It remains in the the stationary phase and starves to death. No liquid yeast culture is 100% wild microflora free. The only thing that keeps the wild microflora at bay while a culture is in the stationary phase is the low pH and/or the ethanol content of solution in which it is stored.

Saccharomyces cerevisiae is one of the most studied microorganisms on the planet. Yet, not one scientific paper exists that supports the practice of rinsing yeast with boiled tap water and/or storing it under boiled tap water. The practice is pure amateur brewer voodoo that is supported by conjecture. In order for a process to be scientifically sound, it must be based on a repeatable experiment that contained controls and a sound protocol for handling the cultures and measuring the results.

 

[Orthobrewsky]

.

Saccharomyces cerevisiae is one of the most studied microorganisms on the planet. Yet, not one scientific paper exists that supports the practice of rinsing yeast with boiled tap water and/or storing it under boiled tap water. The practice is pure amateur brewer voodoo that is supported by conjecture. In order for a process to be scientifically sound, it must be based on a repeatable experiment that contained controls and a sound protocol for handling the cultures and measuring the results.

Fair enough. Tell us about the details of studies which have shown rinsing with boiled tap water to yield bad results relative to not doing so. If people are saying emphatically that rinsing with boiled water is the way it ought always to be done, then they should prove it with careful science. Likewise, if someone says rinsing with boiled water should never be done due to bad results, then they should prove it with careful science.

 

[Orthobrewsky]

Page 168 and 169 go into detail about rinsing with sterile water. Pretty sure they're referring to boiled water. Copyright is 2010. Any links to where they changed their stand on this?

When they describe rinsing, they do use the word "sterile" in reference to the water. I do agree there is no practical difference for us since I don't know of any reason to think that the fermented beer over the yeast has less in the way of microbial impurities than boiled water.

Technically, telling us how to do it isn't a recommendation that we do it. The actual recommendation is near the bottom of page 155:

"Before you use the harvested yeast, you will want to rinse it to separate out the trub and dead cells."

 

[EarlyAmateurZymurgist]

Page 168 and 169 go into detail about rinsing with sterile water. Pretty sure they're referring to boiled water. Copyright is 2010. Any links to where they changed their stand on this?

Chris White is a Ph.D. biochemist. I believes that he knows the difference between sterile and sanitary. To most people who work in science, sterile means autoclaved.

I fairly positive at this point that Jamil wrote the bulk of yeast with Chris White acting in an advisory capacity. I work for a scientific research organization. I interact with scientists
every day. Yeast was clearly written by a non-scientist.

The funny thing is that Chris admits that storing yeast under beer is better than storing it under water when speaking to professional brewers. He also admits that the practice of separating yeast from green beer and non-yeast organic material using sterile distilled water and storing it under sterile distilled water has produced inconclusive results in his lab.

I admire your conviction, but my layman take would be that even if boiled water is not sterile, it’s plenty sanitary for our purposes. That a slurry stored at 35 degrees may not be totally dormant, but it’s plenty dormant for our purposes. And that if any bugs do get past your process, they are more likely to feast on the unfermentable sugars in old beer than boiled water. But I’m a machinist, not a scientist.

Any bugs that get past my process are bugs that one must eradicate from one's brewery with due haste, as they are beer spoilage bugs that result in brewery shutdowns.

What you are overlooking is that storing yeast under boiled water starves the culture to death. Dead yeast cells are a huge reservoir of nutrients. Yeast extract is basically the cell contents of autolyzed yeast cells. It provides an abundance of nitrogen and other nutrients on which bacteria cells can thrive. Storing yeast under green beer prevents wild microflora utilizing the nitrogen that is released when yeast autolyze.


By the way, I do consider "Yeast" to an authoritative reference on the subject of brewing yeast management. The authoritative text on the subject is "Brewing Yeast and Fermentation" by Boulton and Quain.

 

[Orthobrewsky]

I fairly positive at this point that Jamil wrote the bulk of yeast with Chris White acting in an advisory capacity. I work for a scientific research organization. I interact with scientists every day. Yeast was clearly written by a non-scientist.

I agree it was written for non-scientists, however...

"This is a book I wanted to write for a long time. I've written about yeast, spoken about yeast, and worked with yeast every day for what seems like forever. I wanted to put that information and more into one source. I began to write this book three years ago with my brother, Mike White. We put a lot of material together, but it was still missing something. When Jamil Zainasheff came into the project..."

--Chris White from "Acknowledgements" in the book "Yeast"

The funny thing is that Chris admits that storing yeast under beer is better than storing it under water when speaking to professional brewers. He also admits that the practice of separating yeast from green beer and non-yeast organic material using sterile distilled water and storing it under sterile distilled water has produced inconclusive results in his lab.

Does "inconclusive" mean yes, no, or neither?

 

[AnOldUR]

Chris White is a Ph.D. biochemist. I believes that he knows the difference between sterile and sanitary. To most people who work in science, sterile means autoclaved.

Well, here’s the quote from the book.

The question many homebrewers have is , “How do I select only the best yeast if harvesting the entire contents of the fermentor?” The answer lies in yeast rinsing.

He then goes on to describe rinsing with sterile water. So, what you’re saying is that he’s referring the autoclave that all of us have in our homes?

 

[EarlyAmateurZymurgist]

When they describe rinsing, they do use the word "sterile" in reference to the water. I do agree there is no practical difference for us since I don't know of any reason to think that the fermented beer over the yeast has less in the way of microbial impurities than boiled water.

Once again, it's the pH and the antiseptic known as ethanol, not microbiological purity that differentiates green beer from boiled water.

Technically, telling us how to do it isn't a recommendation that we do it. The actual recommendation is near the bottom of page 155:

"Before you use the harvested yeast, you will want to rinse it to separate out the trub and dead cells."

Chris White never mentions this practice when speaking before professional brewers, which leads me to believe that that addition to the book is Jamil's handiwork. I do not consider Jamil to be an authority on anything other than self-promotion.

 

[EarlyAmateurZymurgist]

Well, here’s the quote from the book.
He then goes on to describe rinsing with sterile water. So, what you’re saying is that he’s referring the autoclave that all of us have in our homes?

As I stated earlier, it is clear to me that Jamil wrote the lion's share of "Yeast." No scientist believes that boiled water is sterile because boiling only kills vegetative cells. In world of science, the word sterile has a definite meaning.


http://en.wikipedia.org/wiki/Sterilization_(microbiology)

 

[afr0byte]

Chris White never mentions this practice when speaking before professional brewers, which leads me to believe that that addition to the book is Jamil's handiwork. I do not consider Jamil to be an authority on anything other than self-promotion.

Presumably he saw that part of the book. Apparently he didn't have any great objections to it.

 

[Orthobrewsky]

Once again, it's pH and the antiseptic known as ethanol, not microbiological purity that differentiates green beer from boiled water.

I agree, but then why have you made much of the distinction between boiled water and sterile water in this thread?

 

[afr0byte]

Also, Jamil has mentioned that he uses a pressure cooker for his rinsing water (or did when he still homebrewed).

 

[boydster]

Well, here’s the quote from the book.
He then goes on to describe rinsing with sterile water. So, what you’re saying is that he’s referring the autoclave that all of us have in our homes?

Just so I understand... You're saying that the quote you are referring to about "the answer lies in yeast rinsing" from the book is to be taken at face value, but the quote where it states rinsing should be done with sterile water is open to interpretation? That argument doesn't hold much water. By the same token, one could say: Lots of people have a pressure cooker... Either this book is the one single truth about everything related to brewer's yeast, or it's not. I'm inclined to think it's the latter. There is a lot of great information in Yeast with practical applications, but it is by no means the be-all or end-all of yeast handling.

This thread is furthering a great discussion, and I'm enjoying reading through the debate as it plays out, but this book is being quoted like it is the last word on all things related to brewer's yeast. I'm guilty of quoting it myself, but let's consider what other well educated people have to say on the matter too. How many of us can say we've read Brewing Yeast and Fermentation that EAZ referenced to be able to comment on passages that might be in disagreement with Yeast? I picked up a copy of it about a month ago, but haven't even had a chance to open the cover yet due to moving. If Yeast is the most in-depth literature most of us have read, maybe we can agree that there may some subjectivity and, perhaps, even some inaccuracy in the book that we would better understand with a larger base of knowledge.

 

[mtnagel]

EAZ, you never answered this for me.

- If I want to harvest yeast after fermentation and I'm NOT going to use it to ferment another batch within 1 month (and I don't want to do agar slants and freezing), I can just grab some of the slurry from the fermentor, but every month, I should basically make a starter with it and feed it fresh wort to keep it viable.

Is that correct??

Can you please let me know what I'm supposed to do if I want to keep yeast longer than a month or so and I don't want to do agar slants and freezing?

 

[eastoak]

one thing is certain, jamil does not rinse yeast in his brewery with boiled water, neither does any other brewery.

 

[mtnagel]

They are reusing it very quickly I assume. I wouldn't need to rinse if I brewed every day either.

 

[afr0byte]

They are reusing it very quickly I assume. I wouldn't need to rinse if I brewed every day either.

Also, they can easily drop early trub, and easily select the middle of the yeast cake. Plus, they often repitch in to another batch of the same beer.

 

[EarlyAmateurZymurgist]

I agree it was written for non-scientists, however...

"This is a book I wanted to write for a long time. I've written about yeast, spoken about yeast, and worked with yeast every day for what seems like forever. I wanted to put that information and more into one source. I began to write this book three years ago with my brother, Mike White. We put a lot of material together, but it was still missing something. When Jamil Zainasheff came into the project..."

--Chris White from "Acknowledgements" in the book "Yeast"

There are sections of "Yeast" that were clearly written or dictated by Chris or someone formally trained in the field. However, the more applied sections were clearly written by Jamil. No scientist worth his/her salt would recommend rinsing yeast with boiled tap water. That's Jamil's handiwork. Once again, Chris never mentions the process when speaking before an audience of professional brewers.

Does "inconclusive" mean yes, no, or neither?

In the world of science, inconclusive is a way of saying that a scientist was unable to prove that a process, method, compound, therapy, etc. works as claimed.

The concept of storing yeast under water is based on study that was performed a couple of decades ago. The study was conducted in order to find ways to store cultures long term without refrigeration. The study claimed that small amounts of yeast can be maintained for years under sterile (i.e., autoclaved) distilled water if the culture has been separated from all nutrient sources.

I remember when the practice was introduced to the amateur brewing community back in the nineties. It was really big in the my area because the ATCC offered a course on the technique. Everybody and their brother (including yours truly) got in on the action. Somehow storing small amounts of yeast under autoclaved distilled water morphed into storing cropped yeast under boiled tap water via Internet forum postings.

Chris White stated that he was unable to produce conclusive results when attempting to generalize the technique to include storing crops under sterile water in his lab several years ago. If that situation has changed, I am positive that he would have produced a formal paper for the professional brewing community by now.


By the way, rec.crafts.brewing contributor Dave Whitman wrote an article on the process back in 1996.

http://www.brewery.org/brewery/library/SterileDW1096.html

In the article linked above, Dave makes it clear that boiled water is not sterile.

"Wort, distilled water, and all containers should be STERILIZED (not just sanitized). This means pressure cooking 20 minutes at 15 psi, or repeatedly boiling for 30 minutes on 3 days in a row."

The process of boiling water (or media) for three days in a row is known as tyndallization. The process works by boiling to kill vegetative cells, allowing a day for spores to germinate into vegetative cells, and boiling again to kill the germinated vegetative cells. After three days, it can be assumed that all spores that will germinate have germinated.

Another important part of the recipe is depriving the yeast culture of nutrients. Boiled tap water contains minerals and tiny amounts of colloidal matter, and it is darn near impossible to separate a cropped yeast culture from all of the green beer and organic material without using a centrifuge. Dave makes it clear in his article that the medium has to be completely nutrient free in order to force a complete shutdown of cell metabolism, which is key to the storage method.

"The concept is that in distilled water with no nutrients around, the yeast just go dormant. (That's why you want to avoid transferring any nutrient media when you grab the sample - you're TRYING to starve them). "

In the end, I abandoned the technique because the only advantage that it offered over storage on slants is that the cultures could be stored at room temperature. It did not simplify yeast management in a home brewery environment.

 

[EarlyAmateurZymurgist]

EAZ, you never answered this for me. Can you please let me know what I'm supposed to do if I want to keep yeast longer than a month or so and I don't want to do agar slants and freezing?

I am sorry for not answering your question. I planned to get to it, but thread kept scrolling.

Keeping a liquid culture alive without periodically repitching it is not a viable long-term storage strategy. You can periodically feed the culture by decanting the green beer and adding fresh bitter wort, but that's like putting a band-aid on a sucking chest wound. It may work for a while, but you will eventually have to replace the culture.

 

[EarlyAmateurZymurgist]

I agree, but then why have you made much of the distinction between boiled water and sterile water in this thread?

The distinction has to be made because we raise the pH of the solution and remove an antiseptic compound when we rinse yeast with water. If the culture wasn't infected before being rinsed with boiled water, you can bet that there is a good probability that it well be infected after being rinsed with boiled water. I do not support the practice of storing yeast under autoclaved tap water either, but at least we are giving it a fighting chance by not adding yet another source of infection to the mix while removing its force field.

 

[cervid]

I'm curious what spores or bacteria are such a concern that it really matters. we don't have to worry about, well anything gram positive, brett, lacto, pedio. Those are taken care of with the boiling of the water.

The only thing I can think of is botulism. the toxins from that get killed at 165, but the spores do live. However, considering where it comes from and how rare it is, it's not a concern. If it were present, it would survive in cans of beer people made, since they are not autoclaved. Also, the bacteria that could survive in the boiled water used to wash yeast will not survive mashing and fermentation, especially with the reduced lag time you get from pitching starters anyway.

So, I guess I'm wondering exactly which spores are of such a concern to make such a fuss about it. Maybe acetobacter.. but doesn't it require oxygen to multiply?

Although, because of how I harvest my yeast out of big starters, I am certainly convinced enough to not worry about washing it. It's more a theoretical exercise for those harvesting the crap from the bottom of a fermenter.

If, even the labs can't maintain the level of sterility being proposed by steam pressure sterilization, or the fact that wort isn't sterile, then what does it matter? Wash well, sanitize well either through a no rinse sanitizer or boiling, flame lips, turn off heat/AC, etc, etc.

 

[mattd2]

...Technically, telling us how to do it isn't a recommendation that we do it. The actual recommendation is near the bottom of page 155:

"Before you use the harvested yeast, you will want to rinse it to separate out the trub and dead cells."

But that is not telling you how to harvest the yeast, purely that before you use it the yeast should be rinsed; i.e. you would do the rinsing prior to pitching not after racking. So that quote does not definatively state if they are recomending storage under "sterile" water.

...In the world of science, inconclusive is a way of saying that a scientist was unable to prove that a process, method, compound, therapy, etc. works as claimed, but there is not significant evidence to confirm the intended results can not be acheived.
....

I would have to disagree with you there EAZ, Added one additional important point which completely changes what you have stated

 

[mattd2]

So we basically have imperical results from both methods of storing yeast that the both work. the type of storing yeast in mason jars that we are talking about is something that only homebrewers usually do - professionals would likely directly pitch one fermenter to another, so lets not get side tracked with what the pros do.

So what are the pros/cons for each method - I say next post every does should include their take on the pros/cons for both methods so we can be clear on what it is we are actually arguing

 

[EarlyAmateurZymurgist]

I agree, but then why have you made much of the distinction between boiled water and sterile water in this thread?

The distinction has to be made because we raise the pH of the solution and remove an antiseptic compound when we rinse yeast with water. If the culture wasn't infected before being rinsed with boiled water, you can bet that there is a good probability that it will be infected after being rinsed with boiled water. I do not support the practice of storing yeast under autoclaved tap water either.

 

[Orthobrewsky]

The distinction has to be made because we raise the pH of the solution and remove an antiseptic compound when we rinse yeast with water. If the culture wasn't infected before being rinsed with boiled water, you can bet that there is a good probability that it well be infected after being rinsed with boiled water. I do not support the practice of storing yeast under autoclaved tap water either, but at least we are giving it a fighting chance by not adding yet another source of infection to the mix while removing its force field.

I'm a bit confused. Are you saying you disagree with the guy who said this:

"Once again, it's pH and the antiseptic known as ethanol, not microbiological purity that differentiates green beer from boiled water."

 

[EarlyAmateurZymurgist]

So we basically have imperical results from both methods of storing yeast that the both work. the type of storing yeast in mason jars that we are talking about is something that only homebrewers usually do - professionals would likely directly pitch one fermenter to another, so lets not get side tracked with what the pros do.

You are trying to equate a time-honored, well researched practice of storing yeast under beer with the psuedo science of storing yeast under boiled tap water. The fatal flaw in your argument is that you are saying that science does not apply to amateur brewers.

 

[EarlyAmateurZymurgist]

I'm a bit confused. Are you saying you disagree with the guy who said this:

"Once again, it's pH and the antiseptic known as ethanol, not microbiological purity that differentiates green beer from boiled water."

No, I am disagree with what I wrote earlier. You are twisting what I what wrote earlier. The difference between boiled and sterile (autoclaved) water is that one is completely free of life. That difference doesn't make sterile (autoclaved) water a better choice than green beer.

 

[mattd2]

You are trying to equate a time-honored, well researched practice of storing yeast under beer with the psuedo science of storing yeast under boiled tap water. The fatal flaw in your argument is that you are saying that science does not apply to amateur brewers.

No, I am saying that for a homebrewer that may reuse a yeast for 5 or so generations and then discard and start again that the results from washing/storing with water is "good enough" that it does not end up with multiple failed batches - if it did everyone how did it would be complaining of infected batches with washed yeast.

My argument for not washing is - why bother. The way I see it you gain nothing from washing your yeast (spare one pint of beer!) and it introduces extra processes (and yes where there are extra processes there is the additional chance of infection).
Those that are arguing that washing gets rid of the trub - go back and re-read the OP. It is the same basic process as washing but using green beer instead of boiled water.

Edit: those that a Quoting Kai's experiments as a reason why water is better than beer - Kai was experimenting on yeast growth, not yeast storage. The factors that showed poor yeast growth are quite likely to be benificial for storage as they would also reduce other microorganism's chance at a healthy happy life. The only one that I do see as relevant is the high gravity beers, but this is because you have stressed you yeast druing fermentation and they are likely less viable because of this so you are starting at a weeker start point. Most of what I have read suggests to cut your losses with high gravity beers and start a new round.

Just a side note - because I said lets not do this I picked up some yeast from a brewery the other week. They had it stored in a 1/2 gallon jug with a stopper and airlock. this was yeast specifically for homebrewers to pick up. They did mention to use it within 2 weeks or otherwise make a starter.

The reason I was not storing yeast was the time/hassle of preparing to do so based on the washing technique on HBT. Now I will store as all I have to do is keep my mason jars clean ready to go. I might even branch out into some liquid yeast now ($20 - $30 a pop over here!)

 

[EarlyAmateurZymurgist]

They are reusing it very quickly I assume. I wouldn't need to rinse if I brewed every day either.

You are basing your practice on the false belief that rinsing yeast with boiled tap water is beneficial to the health of the culture, it's not. A culture needs to be kept as aseptic as possible, which is already difficult to do in a brewery setting. Biological quality control is the key to good beer. Most infections are pitched with the culture. Once again, it is easier to propagate a weak culture than it is to clean up an infected culture; therefore, a brewer should focus his/her attention at keeping his/her pitching as clean as possible from a biological point of view, not an ingredient point of view.