Quote:
Originally Posted by Daze
ABV Alcohol by volume this is the % of alcohol that a person end up with assuming all the original sugars are fermented out
PA potential alcohol this is the level of sugar in the mix prior to fermentation
If am approximating it I like to think of things in terms of PA the reason being is it makes things simple. I can then use a chart or my hydrometer to translate PA in to SG after the fact
conversion:
one pound of sugar per gallon is good for about 5% PA. I realize some things like honey take a little more and some sugars take a little less but for the purpose of approximating 1 pound to 5% per gallon is a good rule of thumb
All store bought juices and concentrates are required to have the sugar content on the label and that number is in grams so we need to know the number of grams in 1 pound 453.59237 Since we are approximating I make the math simple and round down to 450.
some recipes are in cups rather than pounds. 1 pound of sugar is on average about 2 cups.
The last thing you need to know is natural sugars if using fresh fruit or juice where you are unsure of the exact grams of sugar you will need to guess. With the exception of grape juice which has tones of sugar most juices (or 3 lbs of fruit to on gallon of water) will result in 180 to 450 grams of sugar with most of them being in the 200-300 range.
Math:
3 cans of apple concentrate 180g sugar each in 1 gallon, what is my PA OG and probable ABV assuming all the sugar ferments out.
180 *3 = 540g
540/450 = 1.2lbs of sugar
1.2 * 5 = 6% PA when you look at a conversion chart that will be an SG of 1.042
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I think answering some common questions is a great idea and I do applaud you taking the initiative to answer some. I see a few things in the ABV calculations that might need clarification.
ABV is alcohol by volume. It is the percentage of alcohol in the beverage calculated by volume. As the sugars ferment, the gravity goes down and the ABV goes up. All the sugar fermenting out is not linked to ABV. I believe your ABV definition actually defines PA. PA is the ABV if all the sugars ferment out.
Two cups is 16 oz liquid, but it is not 16 oz (one pound) of sugar. Different sugars have different weights per cup, but I would guess that most are 12-14 oz per two cups. Using one pound per two cups isn't a big deal if you're using a small amount, but the difference becomes substantial with larger additions.
I am not a fan of working in PA. I think specific gravity is much easier and more accurate. One pound of sugar contains 45 points of gravity. So, one pound of sugar in a one gallon batch raises the gravity by 45 points. One pound in three gallons would raise gravity by 15 points. etc, etc.
The example of a one gallon batch with 1.2 lbs of sugar from the apple concentrate would have a gravity of approx. 1.054 , which has a PA of closer to 7%
1.2*45=54 or 1.054
Another way of looking at it is: one pound of sugar is approx. 450 grams and will raise gravity in a one gallon batch by 45 points. 450 / 45 = 10 So, you can say that you get 1 point of gravity for every 10 grams of sugar per gallon. Dividing the grams of sugar per gallon by ten should give you an approximate gravity. The three cans of concentrate have 540 grams of sugar. 540 / 10 = 54 or 1.054 Make sense?
Also, I don't think you can compare a gallon of juice to 3 lbs of fruit in a gallon of water. For instance, a gallon of apple juice is approx. 8 lbs of juice. 3 lbs of apples will have significantly less sugar than 8 lbs of apple juice.