Planning a ferment

Set it at 1.000 then add enough alcohol to bring it up to 12% ABV. It's the only way to hit 12% exactly. I worked this out to about 18.5 US fl. oz of Everclear to 1 US gallon of wine (well really distilled water to get a starting SG of 1.000).

There is no way you will hit exactly 12% ABV when working with yeast, the best you can do is a ball park estimate. There are just way to many variables that are out of your control.

I think a must with an original SG = 1.090 - 1.093 (brix 21.5 - 22 ) should get you in the ball park of 12% ABV.

Andy

For once I agree completely with Fred! The only way to hit it exactly is mix it from scratch. (Fred and I have a running battle on calculating alcohol.) There are different methods of calculating potential alcohol. And then you have to determine the actual alcohol yield after it is finished. No guarantees on hitting your target. No real guarantee that it will end as bone dry as you wish but that is controllable to some extent. You can only aim. By Fred's method, he would say you would hit 12%. I would say you may hit 13% with the same method. No agreement there. Just pick a method and make what you get. If it turns out too hot, lower the SG in the next batch.

Ray

Andy

Thank you.

Frederick

Andy

Another question. Assuming a normal must, and a normal ferment that does not "stick", if I set my original brix at 22, do I have a reasonable expectation that the wine will have ~12%abv when the ferment is finished ?? Any chance at all that I might end up with 13.2% ??

Frederick

I know where your going because Ray and I have had this discussion before. 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).

Additionally, there are other organisms present in musts that will consume sugar but will not produce ethanol.

In my opinion, even .55 times Brix is very optimistic for home wine making. We don't have the controls they use in the US Davis labs (temp., pitch rates, nutrient balance, etc.) and all of these things can effect the final ethanol production, as will the yeast using respiration rather than glycolysis (the yeast will favor glycolysis in a high sugar environment, but that doesn't mean respiration isn't used at all), and the fact we tend to under pitch so more of the sugar may be used for new cell production.

After all that, I will answer your original questions.

Reasonable, but optimistic (IMHO).

Two chances, slim and nill unless you run this in a very controlled environment. In other words, your not making wine, your trying everything you can to get the most alcohol from the sugar.

Both of these are theoretically impossible. There just aren't enough sugar molecules to create this much alcohol. Of course if you concentrate the wine during or after fermentation by removing only water, all bets are off.

Andy

Andy

Yup - Ray and I argued this for more than a month. At one point we even used the exact same UC Davis material that you are quoting from here. I even pointed out the specific formula that UC Davis uses to produce the PA numbers that we use in our charts, tables, and on our hydrometers. All to no avail I'm afraid. In the end, we couldn't even agree on a single, simple definition for the term "potential alcohol". Thanks for your answer here.

Frederick