Ray

We have _lots_ of experts in this group, and these experts have access
to a wide variety of references. So why don't we just ask the folks
here _point blank_, and see what they can come up with.

Earlier, Andy wrote:
"...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)...."

**Question to the group: Does _anyone_ out there have any modern
reference that_contradicts_what UC Davis has to say on this subject
in any substantive way ????? TIA

Frederick


"Ray" > wrote in message
m...
> Frederick, It is easy to find references to respected authors that use
the
> equations. Can you provide references to respected authors that publish
> information indicating that these equations are wrong?
>
> Thanks
> Ray
>
> "frederick ploegman" > wrote in message
> ...
> >
> > "pp" > wrote in message
> > om...
> > > "Lum" > wrote in message news:<uutAc.480>
>
> > > > > Ar a recent talk, a professional winemaker here from BC mentioned
> that
> > > > > they were getting higher alcohol levels for the starting Brix than
> > > > > they used to, often by 1% or even more. She said this was
confirmed
> by
> > > > > other winemakers from the area. Her hypothesis was that the yeast
> were
> > > > > getting more efficient in alcohol production. This could have
large
> > > > > repercussions if that were indeed the case. I'm wondering if this
is
> > > > > happening in other, hotter areas, as well?
> > > > >
> > > > > Pp
> > > > > Vancouver, Canada
> > > >
> > > > Some types of wine yeast produce more alcohol than others, so the
> above
> > > > situation certainly seems possible. But, I don't understand what
the
> > "large
> > > > repercussions" would be.
> > > > Lum
> > > > Del Mar, California, USA
> > >
> > > Well, if the yeast got consistenly more efficient in producing
> > > alcohol, then the winemaking practice would have to adjust to that
> > > somehow, particularly in hot areas, otherwise we'd end up with hot,
> > > unbalanced wines, no? 1% is a lot as an average change.
> > >
> > > I believe she's been using the same yeast over the years, so it's not
> > > a change in the type of yeast.
> > >
> > > Pp
> > > Vancouver, BC, Canada
> >
> > 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
> >
> >
>
>