sugar to alcohol vol %

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

Reply to
de sik
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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. :o)

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

Reply to
frederick ploegman

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

Reply to
Rob

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

Diane

Reply to
dkistner

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 news: snipped-for-privacy@enews3.newsguy.com...

Reply to
de sik

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