"pp" > wrote in message
om...
> "frederick ploegman" > wrote in message
>...
> >
> > Hi Pp
> >
> > I suspect that this is nothing more than another case of _misapplying_
> > that same old end alcohol formula that pops up every now and then.
> > Using this formula will _always_ produce answers that are 1-2%abv
> > *too high* !! Let me give an example of this:
> >
> > We start a ferment with an OG of 1.090 (22BRIX/12PA). We
> > ferment it down to an EG of 0.990. If we then use that end alcohol
> > formula, it will _try_ to tell us that we have 13.4%ABV in our wine,
> > which of course is wrong.
> >
> > Earlier in this thread, Andy gave us a definition of PA:
> > "...PA is Potential Alcohol, an estimate of the alcohol content if all
of
> > the sugar is consumed. If any sugar is left in the must, you will not
> > reach this potential..."
> >
> > Thus - Our original PA was 12. All of the sugar is consumed in
> > producing that 12%ABV. With no more sugar to consume, our
> > ferment comes to a halt, and there is _no way_ we can reach
> > 13.4%ABV in that wine.
> >
> > It's all very simple. Really !! Tell that lady she hasn't discovered a
> > mutated strain of yeast, she is only MISapplying that method of
> > determining end alcohol. If she doubts this, she can easily pay a
> > lab to test the wine to be sure. HTH
> >
> > Frederick
>
> Frederick:
>
> Only the winemaker could answer this for sure, but I doubt she's
> making simple errors like this. She's one of the best commercial
> winemakers in BC, with a degree from UC Davis. As for lab results, I
> would think she's doing that already but that's just a guess.
>
> As for the PA definition, it sounds reasonable, but I'm wondering what
> formula is being used to equate 22Brix with 12PA? Unless we know that
> we can't be sure the hydrometer PA scale is correct. Going back to
> Lum's post about alcohol yield from sugar, we should be able to
> calculate theoretical maximum PA for a given Brix - I think I saw the
> result in Margalit's Concepts in Wine Chemistry, but I'm waiting to
> get it from library, so can't answer that right now. Anw, I'm willing
> to bet that value is higher than 12PA.
>
> I have some info sheets at home from mostly Napa wineries with Brix,
> TA and final alcohol numbers, I'll try to look those up to bring some
> more data into this discussion.
>
> Pp

I wish you luck, Pp. I, for one, will be very much surprised if the PA
scale on all of the world's hydrometers turns out to be invalid.

Frederick