Yeast Ranching and Sterilization

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barnaclebob

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It seems that as soon as anyone mentions that they are propagating and or freezing yeast the sterilization nazis come out and start preaching and arguing about the definition between sterilization and sanitizing.

And by sterilizing I mean baking everything or putting it in an autoclave up to 240 degrees or whatever.

I understand that when saving small qtys of yeast on plates or slants that sterilization is important due to the relatively small qty of yeast cells in relation to possible contaminants. However I and many others aim to save 100billion cells at a time to eliminate starter steps.

Anyone have any good data on whether sanitizing with boiling water or starsan is more than likely good enough or not good enough in this case?
Does anyone else save yeast using normal brewing sanitizing protocols?
What beer ruining organisms can survive boiling or starsan and then grow in fermentation conditions better than yeast?

My thought is that for someone saving yeast at large enough qtys that sanitizing with boiling water and starsan has a high probability of being adequate for the same reasons that its adequate for starters and beer in general. I realize that each successive propagation will pick up more contaminants and I am going to use a 10 generation limit. I'm willing to take the risk that my yeast will outcompete any contaminates and that any contaminates that don't die wont reproduce at a rate greater than the yeast. Picking up wild yeast while pouring or swabbing seems to be an equal risk for people who sterilize as well.
 
Anyone have any good data on whether sanitizing with boiling water or starsan is more than likely good enough or not good enough in this case?
Does anyone else save yeast using normal brewing sanitizing protocols?
What beer ruining organisms can survive boiling or starsan and then grow in fermentation conditions better than yeast?

Are you talking about sanitizing your equipment? Of course it is good enough. It is just like making a batch of beer, and the common sanitation steps are sufficient for that process. I save small stock quantities of yeast and large, pitchable quantities of yeast, often from the same upscale. The commonly prescribed sanitation methods are good enough, because, as you mentioned:

my yeast will outcompete any contaminates and that any contaminates that don't die wont reproduce at a rate greater than the yeast.

I would venture that more people attempting to save yeast follow the starsan sanitation approach as opposed to full-on sterilization. However, as you also mentioned, sterile conditions are more important with small quantities of yeast. No beer spoilage bacteria/yeast can survive boiling. The only thing that can are the spore-producers, but the fermentation conditions of the wort do not favor the transition into vegetative, growing cells.

I can't think of any reason why you should not attempt to save yeast following common sanitation methods, assuming you are using them correctly. Full sterilization is certainly not a requirement for yeast harvest/storage. There is a difference between sanitation and sterilization, of course, but that shouldn't stop you.
 

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