Newby question RE: cultivating yeast?

There are some procedures archived on the web, search for the brewing FAQ and you'll find them.

Briefly, the procedure requires aseptic techniques, the medium mentioned is malt, with agar added, and the culture is stored in the refridgerator for up to several months before you use it to make a starter, or repeat the process.

If your technique is poor, you'll contaminate your culture. If you keep it too long, it will die. If you repeat the process too many times, you may begin to select against your desired yeast in favor of a less desireable mutant strain.

You'll get better results just buying the yeast. I did use the fine lees from one batch of wine to make some hard cider, but that's as far as I took the yeast recycling.

Buy fresh and keep it sealed tightly in the 'fridge. Yeast is cheap.

Tom S

I did a bit of googling, and the Turbo yeast, like the original poster mentioned, is more expensive -- 6 USD$ for enough to ferment 25 liters to 22% alcohol. Its not like my 0.89 cents for a package of Lavin EC1118.

It appears turbo yeast can't be cultured the way wine or beer yeast can. Its not just the strain of yeast that gives 20% alcohol -- its the special nutrients loaded into the yeast as it goes dormant. You're not going to find those instructions online -- those are trade secrets.

poster

You're

secrets.

I pretty sure (with a little research) you could come up with a nurtient mixture that would work.

The major issue with reusing this yeast is that after sitting in a solution of 20% alcohol, the yeast may not be in the best of shape.

I would recommend that the OP take a fresh culture and make a large starter around SG 1.020 with lots of nutrients added (including O2). When the population has increased, take a portion of the starter for the current fermentation and then add more nutrient mixture to increase the population again.

Andy

This raises a question for me. If the wine is finished fermenting and the yeast has all settled out, is it alive but lacking in sugar/nutrients and thereby dormant, or is it just plain dead???? Hmmm?????

sugar/nutrients

Both. Some of the yeast will die off, but there will still be a lot of live cells that have just gone dormant because of a lack of sugar.

The problem with reusing the yeast is they may be very stressed out at this point, especially if they are in a high alcohol solution. They can have difficulty regulating what passes into and out of the cell. They are also usually very low on compounds required to maintain cell integrety.

Many/most of these compounds can be created by the cells but the process can result in an increase in undesirable chemicals in the wine depending on the available source chemicals.

Andy

Thank you very much for this excellent explanation! Bob

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