"fresh" yeast

[reiternick]

Why would growing a single yeast into a culture provide a healthier yeast than that which is already in the fermented beer? I guess I don't understand why one is more "fresh" than another. They all were recentently budded from another yeast and come from ancestors that budded for millions of years, no?

From "Yeast" book by White:

"Chimay fermentation and yeast practices include a significant amount of laboratory testing. The brewers use new yeast cultures for every batch, and they centrifuge their beer three times to remove yeast after fermentation and add back yeast for bottle conditioning." page 49

I'ved only brewed 30 batches so far, but most of those are from a culture of Sacc Trois that I've kept going. From what I understand, it has probably mutated (~20 re-cultures is a lot from what I've read). Haven't noticed any off flavors yet....

Thanks all

-Nick

 

[Gnomebrewer]

It's not a healthier yeast culture than using one from fermented beer (it is a bit healthier - it hasn't come from an alcoholic, hoppy environment), it's more uniform (you know what you're getting and how that yeast will perform). Like you say, your re-cultured yeast has mutated by now - how much and whether it's in a good, bad or neutral way is variable. Yeast slurry (or washed yeast) that sits in the fridge for a long time will mutate as well - it's normally still viable, but might not perform quite as expected. If you're still happy with your recultured yeast, keep using it! I've used some strains for about 10 generations without problems, while others have changed after three or four.