Saving yeast for years like sourdough?

Howdy all.

I have red through the "how to wash yeast" strains, and hear people saying that you can store it for months, or that you can reuse a yeast cake a few times before it goes bad. However, a sourdough starter can go for well over 100 years if you treat it right.

Is there a reason I can't get a yeast strain to last long for beer making, as long as I use it in a batch, wash the yeast afterward, store as per directed, use again, collect and wash again, etc.? It seems that if I keep feeding it wort and letting it grow and do its thing it should be fine, as these are new yeasts that I collect after every wort, not the same old worn out creatures.

This sounds viable, or do I need to purchase the same yeast after a few batches? I am fine with the yeast morphing into a home yeast blend if it happens to change over time. Seems kinda charming, actually.

Thanks for any thoughts!

well, yeast tends to mutate after a certain number of generations. i can't remember exactly how the calculation goes, but it seems to me it's after like 6 generations or something, but you can get more uses than 6 out of starting with one package of yeast. in theory, you can keep doing it as long as you want, but don't be surprised if it starts tasting odd after a while.

The big issue is contamination will inevitably result, some lacto/pedio or a wild yeast will get in at some point. Now if you wanted to make sour beers you should be good to go using bottle dregs or even in some cases sourdough starter as a yeast source. Also you have no good way to screen for mutations, this combined with the contamination will result in a lot of variability over time in attenuation and flocculation not to mention ester production. Also wild yeasts and bacteria tend to be better able to break down long chain dextrins which provide the body in normal beer.

You could quite happily make lambic style beers in a wooden barrel that you only have to innoculate once.

I've found that upon buying a new vial or smackpack of yeast, it is a lot less hassle in the long run to split the fresh vial or smackpack into several small cleaned and sanitized jars. That way I am always using a first generation yeast and when I want to go use that particular strain all I have to do is wake it out of dormacy by making an appropriately sized starter.

Knowing to break newly bought yeast into several jars for storage to keep it first generation is a good practice. There are ways to propagate your yeast stock, but I've never gone beyond a few generations. Plating yeast is the most efficient way to eliminate infections before they start, but it doesn't eliminate mutations. This is why I find it prudent to rejuvenate the whole stock by heading down to a reputable shop every couple of years or so.

Yes, contamination will inevitably set in. I have doubts about seriously brewers should take the oft-cited mutation concerns, but it's certainly true that it would cause you trouble sooner or later.

If you're willing to learn sterile technique, there is no reason you couldn't maintain yeast stocks indefinitely with regular subculturing and reasonable record-keeping, but it's probably more trouble than it's worth.

I submit that it SHOULD be exactly like maintaining sour dough. And like any living creature will require some maintenance to keep it happy. Consider it a pet, it needs food and water. Maybe some soft music and some gentle stroking. Have you come up with a name for it yet?