"pp" > wrote in message
om...
> "Lum" > wrote in message
>...
> > Ray & Andy,
> >
> > One mole of sugar produces 2 moles of alcohol. The molecular weight of
> > sugar is 180 and the molecular weight of ethanol is 46. So
theoretically,
> > 180 grams of sugar can produce 92 grams of alcohol. 92 divided by 180
is
> > .511 or 51.1 percent.
> >
> > But in practical fermentations, only 90 - 92 percent of the sugar
produces
> > ethanol. The rest of the sugar produces higher alcohols, acetaldehyde,
> > succinic acid, etc.
> >
> > In addition, some alcohol is blown off by the escaping carbon dioxide
gas.
> >
> > See Margalit, "Concepts in Wine Chemistry," page 56.
> >
> > Regards,
> > lum
>
> 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

"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

"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.

Going from 12 to 13 percent alcohol would indeed change the general
character of many wines, but making well balanced, high alcohol wines is not
necessarily difficult. Going from 13.1 to 14.1 percent alcohol results in a
big change in the tax due on commercial wine made in the USA. Of course,
the winemaker can control the alcohol content of the finished wine to some
extent by adjusting the starting Brix (one way or another).

> I believe she's been using the same yeast over the years, so it's not
> a change in the type of yeast.

If she has been propagating her own yeast for many years, I would suspect
the yeast has changed. On the other hand, if she is using dry yeast, then I
suspect the additional alcohol is due to some factor other than yeast.

Regards,
Lum
Del Mar, California, USA

"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

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
>
>

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
> >
> >
>
>

>
> **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

I think we now have the answer to this question. It's what they used
to call "the sound of silence". No one who actually understands this
stuff is going to contradict what the research scientists at UC Davis
have to say on this subject (except yourself).

We covered this material in our private discussion and our discussion
ended several weeks ago when you refused to accept this work as
a modern, authoritative reference. This same material has now been
covered in both this thread and the thread titled "Planning a ferment",
and you have once again ignored or rejected all arguments.

There is nothing more I can do for you, Ray. You will have to
somehow work this out on your own.

"frederick ploegman" > wrote in message >...
> 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
>

Margalit, who was already mentioned in this thread, has higher values.
In Concepts of Wine Chemistry, p. 57 - maximum theoretical yield comes
out as 65% by volume, average practical yield is estimated as 57% of
B, with references to literature that report experimental data in the
values of the actual measured yield of 55%-60% B.

Regards,

Pp

"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

"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

"frederick ploegman" > wrote in message >...
>
> 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

Alright, here is how the hydrometer PA scale does against some real
data. The numbers are from info sheets provided by Napa, Sonoma, and 1
Washington state winery. The wines are marked R (red) and W (white) as
this is significant.

The columns a Brix, final alcohol, PA per hydrometer, delta
(hydrometer - actual).

The PA per hydrometer was calculated by B * (12/22) = B * 0.545 (as
22B = 12PA).

The table is ordered by the delta.

Where B is given as a range, avg value was taken for simplicity.

Type B Final PA Delta
R 25.5 13.5 13.9 +0.4
R 26-27 14.5 14.5 0
W 25.6 14.2 14 -0.2
W 25.2 14 13.8 -0.2
R 24.8 13.9 13.6 -0.3
R 24-25 13.7 13.4 -0.3
R 26.8 15 14.6 -0.4
R 24.2 13.6 13.2 -0.4
R 26.4 15 14.4 -0.6
W 25 14.5 13.7 -0.8
W 23.8 13.9 13 -0.9
W 23.5 13.9 12.8 -1.1
W 23.5-25 14.5 13.3 -1.2
W 23.5 14.2 12.8 -1.4

Average delta all: -0.53; reds: -0.23; whites: -0.83

I'd say not too good overall, particularly for whites. The higher
alcohol in whites vs. reds makes sense and is well supported in
literature. But the formula systematically underestimates even reds in
this sample. Out of 14 wines, 6 are outside of the reasonable +-0.5
delta, with the worst case being -1.4 (that's Napa, Matanzas Creek
Sauv B 2001).

Based on this, I think I could argue that the PA scale on all of the
world's hydrometers leaves something to be desired.

Pp

pp wrote:

> "frederick ploegman" > wrote in message
> >...
>>
>> 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
>
> Alright, here is how the hydrometer PA scale does against some real
> data. The numbers are from info sheets provided by Napa, Sonoma, and 1
> Washington state winery. The wines are marked R (red) and W (white) as
> this is significant.
>
> The columns a Brix, final alcohol, PA per hydrometer, delta
> (hydrometer - actual).
>
> The PA per hydrometer was calculated by B * (12/22) = B * 0.545 (as
> 22B = 12PA).
>
> The table is ordered by the delta.
>
> Where B is given as a range, avg value was taken for simplicity.
>
> Type B Final PA Delta
> R 25.5 13.5 13.9 +0.4
> R 26-27 14.5 14.5 0
> W 25.6 14.2 14 -0.2
> W 25.2 14 13.8 -0.2
> R 24.8 13.9 13.6 -0.3
> R 24-25 13.7 13.4 -0.3
> R 26.8 15 14.6 -0.4
> R 24.2 13.6 13.2 -0.4
> R 26.4 15 14.4 -0.6
> W 25 14.5 13.7 -0.8
> W 23.8 13.9 13 -0.9
> W 23.5 13.9 12.8 -1.1
> W 23.5-25 14.5 13.3 -1.2
> W 23.5 14.2 12.8 -1.4
>
> Average delta all: -0.53; reds: -0.23; whites: -0.83
>
> I'd say not too good overall, particularly for whites. The higher
> alcohol in whites vs. reds makes sense and is well supported in
> literature. But the formula systematically underestimates even reds in
> this sample. Out of 14 wines, 6 are outside of the reasonable +-0.5
> delta, with the worst case being -1.4 (that's Napa, Matanzas Creek
> Sauv B 2001).
>
> Based on this, I think I could argue that the PA scale on all of the
> world's hydrometers leaves something to be desired.
>
> Pp

Would be interesting to see some data from Brix values closer to 22 Brix.
Do you have or could you get data in this area. 25+ Brix values are not
representative of grapes grown in the East. I am wondering if the error
might not be non linear and may in fact be opposite for lower Brix juice.

"pp" > wrote in message
om...
> "frederick ploegman" > wrote in message
>...
> >
> > 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
>
> Alright, here is how the hydrometer PA scale does against some real
> data. The numbers are from info sheets provided by Napa, Sonoma, and 1
> Washington state winery. The wines are marked R (red) and W (white) as
> this is significant.
>
> The columns a Brix, final alcohol, PA per hydrometer, delta
> (hydrometer - actual).
>
> The PA per hydrometer was calculated by B * (12/22) = B * 0.545 (as
> 22B = 12PA).
>
> The table is ordered by the delta.
>
> Where B is given as a range, avg value was taken for simplicity.
>
> Type B Final PA Delta
> R 25.5 13.5 13.9 +0.4
> R 26-27 14.5 14.5 0
> W 25.6 14.2 14 -0.2
> W 25.2 14 13.8 -0.2
> R 24.8 13.9 13.6 -0.3
> R 24-25 13.7 13.4 -0.3
> R 26.8 15 14.6 -0.4
> R 24.2 13.6 13.2 -0.4
> R 26.4 15 14.4 -0.6
> W 25 14.5 13.7 -0.8
> W 23.8 13.9 13 -0.9
> W 23.5 13.9 12.8 -1.1
> W 23.5-25 14.5 13.3 -1.2
> W 23.5 14.2 12.8 -1.4
>
> Average delta all: -0.53; reds: -0.23; whites: -0.83
>
> I'd say not too good overall, particularly for whites. The higher
> alcohol in whites vs. reds makes sense and is well supported in
> literature. But the formula systematically underestimates even reds in
> this sample. Out of 14 wines, 6 are outside of the reasonable +-0.5
> delta, with the worst case being -1.4 (that's Napa, Matanzas Creek
> Sauv B 2001).
>
> Based on this, I think I could argue that the PA scale on all of the
> world's hydrometers leaves something to be desired.
>
> Pp

Hi Pp

No serious student of winemaking would consider this to be "real data".
But I know that you are serious about this and I will try to give you
a serious answer here. To this end, let me give you an easy way to
evaluate this data for yourself.

Keep in mind that the maximum *theoretical* conversion rate is
about 0.60, and the maximum *realistic* conversion rate is about 0.55.
It is this realistic rate that we find on our hydrometers.

All you have to do is divide the end alcohol by the original BRIX to
see how this data compares to reality.

In your fist example we would divide 13.5(ABV) by 25.5(BRIX) and
get 0.529. This is slightly less than the expected 0.55 rate and would
lead us to expect that a small amount of sugar was unconsumed and
was left in the wine as "residual" sugar.

In your last example we would divide 14.2(ABV) by 23.5(BRIX) and
get 0.6043. This exceeds even the theoretical maximum (even
without _any_ losses) !! Obviously there is something seriously wrong
with these numbers.

I might also point out that in at least 3 of these examples they are unsure
of their original BRIX numbers, which automatically indicates that this
"real data" isn't credible.

There is of course a much easier way to do this. Since the "realistic"
calculations have already been done for us and appear in the PA
scale on our hydrometers, simply compare the end alcohol to the
original PA for that wine. If the end alcohol exceeds the predicted
(potential) alcohol, you automatically know that something has gone
wrong with your end alcohol calculation.
HTMS, HTH

Frederick

"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?"

In addition to wine I make a lot of beer. I use Wyeast liquid yeast and
prepare a starter for my 6 gallon batches. Once fermentation is complete I
reuse the yeast for another batch. I do this again for a third batch. To
reuse the yeast I pour the new batch of wort onto the yeast cake from the
previouse batch. There is a lot more yeast present for the second and third
batches. These batches always ferment down lower than the first batch, thus
creating more alcohol. Makes me wonder if the winemaker mentioned above is
using variable amounts of yeast and perhaps that is the reason for the
increased alcohol. Beer never ferments to zero like wine. Seems like the
only way you can end up with more alcohol in wine is to start with more
fermentables.

Bill Frazier
Olathe, Kansas USA