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From: rcd@opus.UUCP (Dick Dunn)
Newsgroups: net.wines
Subject: Re: Yeast strains and boozology (and headaches)
Message-ID: <1100@opus.UUCP>
Date: Tue, 19-Feb-85 15:13:28 EST
Article-I.D.: opus.1100
Posted: Tue Feb 19 15:13:28 1985
Date-Received: Wed, 20-Feb-85 13:53:24 EST
References: <522@hou5g.UUCP>
Organization: NBI,Inc, Boulder CO
Lines: 25

> ...different chemical goodies. It's the same as different
> beers/wines having different amounts of ethanol - it's not
> because individual breweries throw in different amounts of
> industrial alcohol, but because the yeast strain used for
> that brew dies off at that ethanol concentration...

Not true.  Most beer yeasts are capable of producing as much as 10-12% alc
(vol), which is about double what's typically present.  Wine yeasts can
probably tolerate 18-20% alc.  Fermentation stops either because all of
the fermentable sugars are gone--as with beers--or because the yeast is
intentionally killed off chemically--as with some wines.  The end product
is then generally either filtered or settled out (perhaps with flocculating
agents) to get rid of the remaining yeast, which can otherwise contribute
off-flavors.  Finally, almost all beers are pasteurized in order to ensure
that no viable yeast (or other microbeast) remains to nibble on the brew.

A few beers (from smaller breweries) are not filtered; the
yeast is left in and the last little bit of fermentation takes place in the
bottle in order to carbonate the beer.  It's like Methode Champenoise
except that the yeast stays in the bottle.  The yeast sediment from the
bottom of bottles of this sort can often be cultured into a usable yeast
for brewing if you're VERY careful to avoid contamination.
-- 
Dick Dunn	{hao,ucbvax,allegra}!nbires!rcd		(303)444-5710 x3086
   ...Relax...don't worry...have a homebrew.