Hi, long time lurker here. I am very interested in traditional brewing practices, and in researching the methods used in the past it is very hard to find information about yeast, primarily because brewers were unaware of its existence until recently. I would like a mixed strain yeast that I can reculture infinitely. The goal would be to develop a mix of yeasts that would be a 'house blend' and would mutate over time. The reculturing technique would be scooping off the yeasty head of active beer, using the sludge at the bottom of the fermenter, or simply pouring part of the old batch into the new one. The fermenter will eventually be a wooden barrel, so that should help to carry the yeast over between batches.

Is it feasible to continue this for years? Will yeast mutations cause undrinkable beer? The alternative is to use wild yeast in every batch, which would allow an amount of consistency and reduce the chances of contamination of the yeast culture. Is this a better option? If so, what types of wild yeasts are good for making beer? I know specific wild yeasts are associated with certain plants, what plants can I grow that will have tasty yeasts on them?

Thank you very much for your time. If possible, answers to both sets of questions would be very helpful. Looking forward all the info this year!

-Will in Oregon

RESPONSE:

Will,

I assume you will produce ale styles if you want to use traditional brewing practice. In this case reusing the yeast for indefinite times is house blend possible. There are a couple of breweries which reuse their yeast for more than 10 years now. You will have some mutations over time like changes in flocculation, sugar use and so on... but undrinkable is a very subjective measure. I probably have a different definition of undrinkable than you do. The most common yeasts in beer are Saccharomyces species but you can also find some Brettanomyces (see lambic beers) or Torulaspora.

Wild yeasts in beer are not so much originated from plants/raw materials than from the environment in your fermentation room (air, fermentation vessel...). All yeasts that are originated from malt or hop will be killed during the boiling of the wort. One way to get the "wild" yeast from your house flora is to leave strong hopped wort without yeast in an open fermentation vessel and wait until it starts to ferment. You will have initially all kinds of yeast and bacteria in your wort but the hop and the fermentation products (alcohol and CO2) will be selective and only a few yeast species and bacteria will survive in the finished beer.

You can crop the yeast start a new batch. If the beer is to your liking you can use the crop yeast as your "house blend".

Tobias