I'm baffled; I'm mystified, I'm confused. The more I look up and read about
the conversion of sugar to ethylalcohol, the more confused I get. Virtually
everyone seems to state something else. The numbers go from 17 grams of
sugar for 1 vol.% of alcohol in a liter to as much as 21 grams or even more.
I know, I know: 180 grams of sugar convert theoretically into 92 grams of
alcohol. Density of alcohol is 0,794 (15C/15C), so 92:180 = 0,5111, so
0,5111 x 100 : 0,974 (density)= 0,6437. 17 grams of sugar = 17 x 0,6437 =
10.940 ml which gives 1,094 vol% in a liter. But somehow I don't believe
that. Apart from the fact that is is a theoretical yield, and you can"t get
that far in real life, I am missing the "shrinking factor" because 1 liter
of water and 1 liter of alcohol put together don't make up 2 liters, but
less. Now I don't know how to put things in the right spot. Help is wanted.
When I want to make a "light" wine I don't want to end up with far too less
alcohol.

I would appreciate the theory but would enjoy to also hear from the old
foxes in the art of winemaking. Lum?

Ed

Hi Ed

I was hoping that someone else would answer this one. I really don't
appreciate always having to be the bad guy when it comes to these
kinds of posts. (hint, hint) But - let me give it a try.

You are confusing the "theoretical" numbers with the real life, practical
numbers. (not an uncommon mistake it seems)
Theoretical values live in a perfect word, and yeast sure ain't perfect !!
In real life, sugar is
converted to alcohol by an inefficient living organism, so only the numbers
based on empirical data derived from_actual_experimentation are valid
since these are the numbers which tell us what yeast are capable of doing.
Thus, "theoretical" values are useless for practical winemaking. In fact,
to the extent that they only serve to confuse the unwary, they are
_worse_ than useless !! They certainly don't describe what actually
happens in_my_fermenters !! Quite frankly, I feel that such "theoretical"
values should be labeled as "off topic" in a group that is concerned with
_practical_winemaking !! (but that is just me I guess)

Ok, ok, end of rant. )

Anyway - unless or until you learn to separate the "theoretical" from the
real life numbers you are going to remain confused. It's fine to discuss
one or the other so long as you don't try to shuffle them together like
a deck of cards. Not the answer you were looking for but it's the best
one I have. HTH

Frederick


"de sik" > wrote in message
...
> I'm baffled; I'm mystified, I'm confused. The more I look up and read
> about the conversion of sugar to ethylalcohol, the more confused I get.
> Virtually everyone seems to state something else. The numbers go from 17
> grams of sugar for 1 vol.% of alcohol in a liter to as much as 21 grams or
> even more. I know, I know: 180 grams of sugar convert theoretically into
> 92 grams of alcohol. Density of alcohol is 0,794 (15C/15C), so 92:180 =
> 0,5111, so 0,5111 x 100 : 0,974 (density)= 0,6437. 17 grams of sugar = 17
> x 0,6437 = 10.940 ml which gives 1,094 vol% in a liter. But somehow I
> don't believe that. Apart from the fact that is is a theoretical yield,
> and you can"t get that far in real life, I am missing the "shrinking
> factor" because 1 liter of water and 1 liter of alcohol put together don't
> make up 2 liters, but less. Now I don't know how to put things in the
> right spot. Help is wanted. When I want to make a "light" wine I don't
> want to end up with far too less alcohol.
>
> I would appreciate the theory but would enjoy to also hear from the old
> foxes in the art of winemaking. Lum?
>
> Ed
>

So, let's follow up Fredrick's post with some applied theory (and feel
free to flame/enhance my comments if needed, Fredrick, as my experience
as a winemaker isn't enough to be exact, but as a scientist/engineer it
shoulf be enough to knock off the rough edges).

Reality never reaches the full extent of theory. So if you take the
most efficient measure of conversion to alcohol, you know that that's
your maximum alcohol content possible. Use brix measurements, and the
further past 1.00 you go, the closer to the theory you get. What
doesn't convert, well, that's the yeasties being inefficient and lazy
(One can almost hear the yeast equivalent of Donald Trump swimming
through the fermenter, sticking out his pseudopod, and squeaking
"you're fired"). The "fudge factor" you're looking for if actually
hidden in the published differences between the conversion rates: the
spread between a 17 grams and 21 grams of sugar for 1 vol.% of alcohol
in a liter is likely the practical range the different authors (and
their sources) have found for their real-life experience.

What this really means is that if you "design" your winemaking process
to make a % alcohol at the most efficient rate, you'll likely end with
a wine with a slightly lower alcohol content than you thought. It'll
actually make it easier to make a "light" wine. I've personally given
up on actually measuring final alcohol content, as, being cheap, I
can't find a good simple measurer (I've never run into a vinometer that
told me that distilled H20 was actually 0% alcohol, for instance,
although that may be how they sterilize that stuff... Hmmm...), and
now I just compute expected alcohol content from starting sugar content
from my hydrometer, and I might round off 0.5% alcohol if it were to
stop at .990 instead of .980.

Hope that helps,and any clarification I need from those who know even
more about this than I do, please hop in.

Rob

So, let's follow up Fredrick's post with some applied theory (and feel
free to flame/enhance my comments if needed, Fredrick, as my experience
as a winemaker isn't enough to be exact, but as a scientist/engineer it
shoulf be enough to knock off the rough edges).

Reality never reaches the full extent of theory. So if you take the
most efficient measure of conversion to alcohol, you know that that's
your maximum alcohol content possible. Use brix measurements, and the
further past 1.00 you go, the closer to the theory you get. What
doesn't convert, well, that's the yeasties being inefficient and lazy
(One can almost hear the yeast equivalent of Donald Trump swimming
through the fermenter, sticking out his pseudopod, and squeaking
"you're fired"). The "fudge factor" you're looking for if actually
hidden in the published differences between the conversion rates: the
spread between a 17 grams and 21 grams of sugar for 1 vol.% of alcohol
in a liter is likely the practical range the different authors (and
their sources) have found for their real-life experience.

What this really means is that if you "design" your winemaking process
to make a % alcohol at the most efficient rate, you'll likely end with
a wine with a slightly lower alcohol content than you thought. It'll
actually make it easier to make a "light" wine. I've personally given
up on actually measuring final alcohol content, as, being cheap, I
can't find a good simple measurer (I've never run into a vinometer that
told me that distilled H20 was actually 0% alcohol, for instance,
although that may be how they sterilize that stuff... Hmmm...), and
now I just compute expected alcohol content from starting sugar content
from my hydrometer, and I might round off 0.5% alcohol if it were to
stop at .990 instead of .980.

Hope that helps,and any clarification I need from those who know even
more about this than I do, please hop in.

Rob

Rob wrote:
> What
> doesn't convert, well, that's the yeasties being inefficient and lazy
> (One can almost hear the yeast equivalent of Donald Trump swimming
> through the fermenter, sticking out his pseudopod, and squeaking
> "you're fired").

OMG, this is the best HOWL I've had all year! And how vividly
instructive....

Diane

Took you a long time ;-). Found something though. Pieper, Bruchmann/Kolb in
"Technologie der Obstbrennerei" (Technology of fruitdistillates) (Yes,
written in German) state that 1 kg of fructose yields theoretically 0,6436
liter of alcohol. Pasteur however has proven that about 5 % of the sugar is
lost at the start of the process, when yeast in presence of oxygen does not
make alcohol but more yeast; makes glycerine in stead of alcohol; makes
acetaldehyd etc. Another 5 % goes down the drain by bacteria; while
fermenting some alcohol will disappear with the CO2 and when racking some
will be lost. At best you can make 0,56 liter of alcohol from 1 kg fructose
or glucose. That means that we have to use at least 18 grams of sugar for 1
%vol alcohol per liter. For me 18,5 grams works best.
Ed

No flowers, no bees,
no leaves on the tree,
no wonder;
november.


"frederick ploegman" > schreef in bericht
...
> Hi Ed
>
> I was hoping that someone else would answer this one. I really don't
> appreciate always having to be the bad guy when it comes to these
> kinds of posts. (hint, hint) But - let me give it a try.
>
> You are confusing the "theoretical" numbers with the real life, practical
> numbers. (not an uncommon mistake it seems)
> Theoretical values live in a perfect word, and yeast sure ain't perfect !!
> In real life, sugar is
> converted to alcohol by an inefficient living organism, so only the
> numbers
> based on empirical data derived from_actual_experimentation are valid
> since these are the numbers which tell us what yeast are capable of doing.
> Thus, "theoretical" values are useless for practical winemaking. In fact,
> to the extent that they only serve to confuse the unwary, they are
> _worse_ than useless !! They certainly don't describe what actually
> happens in_my_fermenters !! Quite frankly, I feel that such "theoretical"
> values should be labeled as "off topic" in a group that is concerned with
> _practical_winemaking !! (but that is just me I guess)
>
> Ok, ok, end of rant. )
>
> Anyway - unless or until you learn to separate the "theoretical" from the
> real life numbers you are going to remain confused. It's fine to discuss
> one or the other so long as you don't try to shuffle them together like
> a deck of cards. Not the answer you were looking for but it's the best
> one I have. HTH
>
> Frederick
>
>
> "de sik" > wrote in message
> ...
>> I'm baffled; I'm mystified, I'm confused. The more I look up and read
>> about the conversion of sugar to ethylalcohol, the more confused I get.
>> Virtually everyone seems to state something else. The numbers go from 17
>> grams of sugar for 1 vol.% of alcohol in a liter to as much as 21 grams
>> or even more. I know, I know: 180 grams of sugar convert theoretically
>> into 92 grams of alcohol. Density of alcohol is 0,794 (15C/15C), so
>> 92:180 = 0,5111, so 0,5111 x 100 : 0,974 (density)= 0,6437. 17 grams of
>> sugar = 17 x 0,6437 = 10.940 ml which gives 1,094 vol% in a liter. But
>> somehow I don't believe that. Apart from the fact that is is a
>> theoretical yield, and you can"t get that far in real life, I am missing
>> the "shrinking factor" because 1 liter of water and 1 liter of alcohol
>> put together don't make up 2 liters, but less. Now I don't know how to
>> put things in the right spot. Help is wanted. When I want to make a
>> "light" wine I don't want to end up with far too less alcohol.
>>
>> I would appreciate the theory but would enjoy to also hear from the old
>> foxes in the art of winemaking. Lum?
>>
>> Ed
>>
>
>

de sik wrote:
> I'm baffled; I'm mystified, I'm confused. The more I look up and read about
> the conversion of sugar to ethylalcohol, the more confused I get. Virtually
> everyone seems to state something else. The numbers go from 17 grams of
> sugar for 1 vol.% of alcohol in a liter to as much as 21 grams or even more.
> I know, I know: 180 grams of sugar convert theoretically into 92 grams of
> alcohol. Density of alcohol is 0,794 (15C/15C), so 92:180 = 0,5111, so
> 0,5111 x 100 : 0,974 (density)= 0,6437. 17 grams of sugar = 17 x 0,6437 =
> 10.940 ml which gives 1,094 vol% in a liter. But somehow I don't believe
> that. Apart from the fact that is is a theoretical yield, and you can"t get
> that far in real life, I am missing the "shrinking factor" because 1 liter
> of water and 1 liter of alcohol put together don't make up 2 liters, but
> less. Now I don't know how to put things in the right spot. Help is wanted.
> When I want to make a "light" wine I don't want to end up with far too less
> alcohol.
>
> I would appreciate the theory but would enjoy to also hear from the old
> foxes in the art of winemaking. Lum?
>
> Ed
>
>
Th erotically each molecule of sucrose (12 carbons) will yield 4
molecules of ethanol (8 carbons) and 4 carbons will be lost as CO2 if we
could carry out these reactions in a reactor. However, if we look at
where the carbon really goes (a process called metabolism) then
everything that the cell makes, cell walls, cell membranes, amino acids,
lipids, etc must be produced mostly from carbon that is supplied by the
sugar in the grapes and any additional sugar that is added. When we see
the residue in the bottom that is dead yeast we are basically looking at
sugar that was not used to produce ethanol. All of the pathways compete
for the carbon that we as wine makers wish would flow exclusively to
ethanol through fermentation.

Greg