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ABV calculation - back sweeting

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snoopthulhu

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How does back sweeting affect ABV calculations?

My wine started at 1.097 SG, and is now at the tail end of second stage fermentation, with a SG of 0.990 (still outgassing!!!). Calculations tell me that's approximately 14% ABV right now. However, it's a little dry for my taste, and I want to back sweeten it.

Do I recalculate based on SG after sweeting, or not, or...
 

jgmann67

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I liked it the first way... it drowsies in the calculations for me all the time. :db

Does it change the calculation going the other way, though? If it does, I think only negligibly.

Example: You ferment your wine down to 0.992 from 1.100, so your 23 liters of wine lands some where around (I'm guessing) 14.2% ABV. Then you add 500 ml of an FPac. I agree that the fact that your SG is now 0.998 doesn't increase the ABV unless you continue fermentation. But now, the 14.2% @ 23 Liters is X% @ 23.5 Liters. More volume = decreased ABV, but not in any noticeable way.

Is this right?
 
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Johnd

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I liked it the first way... it drowsies in the calculations for me all the time. :db

Does it change the calculation going the other way, though? If it does, I think only negligibly.

Example: You ferment your wine down to 0.992 from 1.100, so your 23 liters of wine lands some where around (I'm guessing) 14.2% ABV. Then you add 500 ml of an FPac. I agree that the fact that your SG is now 0.998 doesn't increase the ABV unless you continue fermentation. But now, the 14.2% @ 23 Liters is X% @ 23.5 Liters. More volume = decreased ABV, but not in any noticeable way.

Is this right?
'Tis perfectly correct. The effect with fpacks and simple syrup is more pronounced, they're made with water and change the volume more than straight sugar, which dissolves just fine in wine without added water.
 

snoopthulhu

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Does it change the calculation going the other way, though? If it does, I think only negligibly.

Example: You ferment your wine down to 0.992 from 1.100, so your 23 liters of wine lands some where around (I'm guessing) 14.2% ABV. Then you add 500 ml of an FPac. I agree that the fact that your SG is now 0.998 doesn't increase the ABV unless you continue fermentation. But now, the 14.2% @ 23 Liters is X% @ 23.5 Liters. More volume = decreased ABV, but not in any noticeable way.

Is this right?
This was my concern, changing the overall volume. Thanks all for the replies!
 

Julie

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Instead of using an FPac just take some wine out, heat it up, add the sugar and add it back.
 

Julie

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AHHH But don't you lose some alcohol through evaporation when you heat it up?


(Just kidding - being a PITA)
I am only taking out about a cup maybe two and I warm it up, do not boil. If I lose any alcohol it would be roughly .00something?
 

Scooter68

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Yup. minor loss from one cup. 16 cups to a gallon so if your ABV is solid (Above 12.5%) I don't see how that small loss would affect anything. IF you lost all the alcohol in one cup that would drop your 14% down to a hair over 13% - Still good.
 
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Julie

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Scooter68! Lol, when I responded I didn't see the "(Just kidding - being a PITA)"
 

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