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You are here: Home --> Forum Home --> Brewing Forum --> Brewing Discussion --> What makes yeast wild?

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mutedog
Washougal, WA
29 Posts


inspired by a short conversation I had on twitter earlier. What do you consider to be wild yeast?

It seems there are a number of competing definitions out there.





Posted 34 days ago.

Matt
Charter Member
Normal, IL
341 Posts


Huh, never thought about this. I guess I consider wild yeast anything that isn't made commercially in a lab, so no wyeast, no white labs, no professional breweries. 



Posted 34 days ago.

homebrewdad
Charter Member
Birmingham, AL
2480 Posts


I'd agree with Matt.  Anything that isn't professionally cultivated.



Posted 34 days ago.

ingoogni
nl
314 Posts


Anything that is not domesticated, but from a brewers point of view more specific also anything that is not S.cerevisiae or S.uvarum (or what it is called nowadays). Even if we think a Brett from a lab is not "wild" we still call it that to keep the vocabulary in line.




Posted 34 days ago.

mutedog
Washougal, WA
29 Posts


So I have a 'wild' yeast that I've been using for 3+ years. It's (probably) not brett. Is it still wild?



Posted 34 days ago.

Matt
Charter Member
Normal, IL
341 Posts


Did you cultivate it yourself from a fruit or something?



Posted 34 days ago.

mutedog
Washougal, WA
29 Posts


yes



Posted 34 days ago.

Matt
Charter Member
Normal, IL
341 Posts


Wild! In my opinion



Posted 34 days ago.

uberg33k
Charter Member
The Internet
314 Posts


Yeast stops being wild once it undergoes enough selective breeding that it develops characteristics that distinguishes it from its originator.  Is your yeast starting to behave differently now than when you first captured it?  If so, it's no longer wild.

I'd even say that a lot of lab grown Brett is probably no longer wild.  Same thing with most bacteria, especially those that have developed hop tolerance.




Posted 34 days ago.

chino_brews
Charter Member
Eden Prairie, MN
301 Posts


Well one way to look at is by analogy to the animal kingdom: an animal is no longer wild when it is domesticated.

So when is yeast domesticated?, you might ask. Looking to the animal kingdom again, an animal is domesticated when it is tamed to cooperate with us and do a job we need it to do. Further, a hallmark of all domesticated animals that were not quit recently domesticated is that it has been bred by natural selection to perform better for its human purpose. Thus, herding dogs are bred to be good at running, herding, and protecting flocks of animals, sled dogs are bred to be strong for pulling sleds, to have a pulling instinct, and do well in the cold, and retrievers are good at swimming and retrieving waterfowl. These changes are visible in the genomes of the breeds.

You could look at plants in the same light.

As far as yeast, they were domesticated initially when captured and reused for brewing (as opposed to "wild yeasts" in new open air fermentations, where the yeast is not maintained), and were further adapted for the purpose (whether intentionally or not) by techniques such as using brooms or twigs to hold and innoculate yeast, top or bottom cropping, etc.

Also, because yeast can reproduce every 90 minutes, the domestication process can occur very rapidly.

To sum up, I'd say any yeast that a brewer maintains for brewing purposes has become domesticated and "not wild" after some small number of successive repitches as long as it has stabilized around some consistent performance characteristics.




Posted 34 days ago.

ingoogni
nl
314 Posts


Domestication of Silver foxes

Reproduction of yeast is fast, but only once a brew there is selective pressure. To get real selection you need to select the "best" yeast from several batches and continue with that one and repeat the process several times. But yes, it takes relative few batches with consistent selection criteria to create domestication.




Posted 34 days ago.

mutedog
Washougal, WA
29 Posts


I sort of agree with uberg33k and chino_brews here.

I'd say a yeast is no longer wild when certain things are known about it. Like what is the optimal fermentation temperature range, what is its attenuation, what types of flavors can be expected from it. So with this definition there are varying degrees of domestication, my 'wild' yeasts are mostly domesticated, but I haven't tried them in a number of temp ranges so I don't know what to expect if I tried to ferment them at lager temps or at 100F but I know what to expect when I do typical ale temp ranges. I know sort of what to expect as far as attenuation though I haven't specifically measured it (typically they are 'high' attenuators) and I know what sort of flavors to expect from most of them, though a few I haven't done long term tests to see if brett character shows up or not.

So I don't think any yeast or bacteria you buy from a lab can really count as wild; its behavior is well known and you generally know what to expect from it when you pitch it in your wort.




Posted 34 days ago.

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