Andy

Yup - Ray and I argued this for more than a month. At one point we
even used the exact same UC Davis material that you are quoting
from here. I even pointed out the specific formula that UC Davis uses
to produce the PA numbers that we use in our charts, tables, and on
our hydrometers. All to no avail I'm afraid. In the end, we couldn't
even agree on a single, simple definition for the term "potential alcohol".
Thanks for your answer here.

Frederick

"JEP" > wrote in message
om...
> "frederick ploegman" > wrote in message
>...
> >
>
> I know where your going because Ray and I have had this discussion
> before. My literature from UC Davis says (paraphrasing):
>
> The theoretic maximum yield of ethanol is around .6 times the initial
> Brix. This would give a maximum yield of 13.2 ABV for a 22 Brix must.
> My reference goes on to say that .55 times the initial brix is really
> all we can get in practice, which would yield around 12.1 ABV. This is
> because a varying percentage of the sugar is used for other things and
> even if the fermentation does not stick, there is a percentage of
> sugar that ends up as other end products (like glycerol, pyruvate,
> acetate, acetaldehyde).
>
> Additionally, there are other organisms present in musts that will
> consume sugar but will not produce ethanol.
>
> In my opinion, even .55 times Brix is very optimistic for home wine
> making. We don't have the controls they use in the US Davis labs
> (temp., pitch rates, nutrient balance, etc.) and all of these things
> can effect the final ethanol production, as will the yeast using
> respiration rather than glycolysis (the yeast will favor glycolysis in
> a high sugar environment, but that doesn't mean respiration isn't used
> at all), and the fact we tend to under pitch so more of the sugar may
> be used for new cell production.
>
> After all that, I will answer your original questions.
>
> > Another question. Assuming a normal must, and a normal ferment that
> > does not "stick", if I set my original brix at 22, do I have a
reasonable
> > expectation that the wine will have ~12%abv when the ferment is
> > finished ??
>
> Reasonable, but optimistic (IMHO).
>
> > Any chance at all that I might end up with 13.2% ??
>
> Two chances, slim and nill unless you run this in a very controlled
> environment. In other words, your not making wine, your trying
> everything you can to get the most alcohol from the sugar.
>
> > 14.4% ?? Maybe even 16% ??
>
> Both of these are theoretically impossible. There just aren't enough
> sugar molecules to create this much alcohol. Of course if you
> concentrate the wine during or after fermentation by removing only
> water, all bets are off.
>
> >
> > Frederick
>
>
> Andy