Calculating ABV % after backsweetening

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wildhair

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Since % ABV stands for the Percentage of Alcohol by Volume - it only stands to reason that adding syrup or juice concentrate after fermenting will change that ratio. If you add more liquid (thereby increasing the volume) but you don't add any additional alcohol - you have decreased the % of alcohol in the new, larger volume.
I got some help with the math on the Home Winemaking FB page and put together a spreadsheet to assist others with the calculations. As I understand it - to calculate the ABV of your wine when it is dry - you take the beginning SG, subtract the ending SG (dropping the decimals) then divide the result by 7.36.
So - starting SG @ 1.090 > ending sg .990 = 1090 - 990 = 100. Divide 100 by 7.36 = 13.58% ABV.

I wanted to know because I have 5.5 gal of Dragon's Blood and my notes say last time I added 6 cans (12 oz each) of juice concentrate to backsweeten and boost the flavor. That's 72 oz (6 X 12) added to 704 oz (5.5 gal X 128 oz per gal) - almost a 10% increase in volume.
So now I have 776 oz (a bit over 6 gal) - but the same amount of alcohol. What would the NEW % ABV be??

If you input your starting and ending SG in the highlighted boxes (w/o decimal points) and your volume BEFORE adding sweetener and the volume of sweetener - it should do the calculations for you.

Unfortunately - I don't seem to be able to upload either and Excel spreadsheet or a Libre open source document - (.ods)

So - here's a link to get to it. It's in LibreOffice and Excel format for those of you that are Microsoft hostages. Let me know if you can't open it.

http://www.simpsontaxidermy.com/WinePage.html

Hope it helps someone.
 
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Hey. I found that spreadsheet, and it is very useful, but can anyone please explain the math here so I can understand it without using the spreadsheet and calculate it myself?
Any help is appreciated.
I don't often have to backsweeten with more the half cup simple syrup tops so I've never had to deal with cutting a batch with a quart or more of juice but now find a need to.
 

sour_grapes

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I am not 100% sure I understand the question, but here is an attempt to answer a question you MAY be asking! :)

Before backsweetening, you presumably know the ABV and the volume. Multiply those to determine the volume of ethanol you have. Then you add non-alcoholic ingredients. Now you have a new volume (but you have not added any alcohol). Divide the old ethanol volume by the new volume of the wine to get a new ABV.

Example:

You have 5 gallons of skeeter pee at 14% ABV. This means you have 5 gallons * 0.14 = 0.7 gallons of ethanol*. You then add 1 gallon of some simple sugar solution to your liking. Your wine is now 6 gallons total volume. Your new ABV is (0.7 gallon)/(6 gallons) = 11.7% ABV.

*To the expert reader: I am well aware that when you mix ethanol and water, volume is not conserved. That is WHY we specify ABV rather than some other ratio. However, that factor does not enter into this calculation because the beginning and ending results are similarly diluted.
 
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BernardSmith

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I may be wrong but my practice is to simply check the increase in volume that the sugar or syrup adds: so say the original volume was 5 gallons and the SG was 1.090 ( potential ABV of 11.8 %) but after adding the syrup the new volume is 6 gallons , To allow 5 gallons to be 1.090 there would need to be about 10 lbs of sugar total dissolved in the "water". Now, the volume is 6 gallons, we need to divide the 10 lbs by 6 = 1.67 lbs in each gallon, which would be an SG = 1.075 which is = 9.8% .
 
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Yes that was the question I was asking.
Like I said I rarely need to backsweeten. I usually make my wines sweet to begin with.

But in this instance I was making a test batch of pineapple/apple cider in a small 1 & 1/2 gallon batch. After a few days I stopped seeing activity in my airlock and added just a pinch of yeast energizer and the ferment ended up at 14% and the alcohol flavor is strong (I normally shoot for 9-10% to prevent this. I start my wines at 1.1 and stop at 1.03 or 1.02 this time it went to .99) so I'm planning on cutting it with apple and pineapple juice. These will likely be small amounts like a quart of apple and 16oz of pineapple. Which means ill have to convert volume to ounces (possibly quarts if I use 2 16oz pineapple) and will need to calculate the new ABV
 

BernardSmith

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Yes that was the question I was asking.
Like I said I rarely need to backsweeten. I usually make my wines sweet to begin with.

But in this instance I was making a test batch of pineapple/apple cider in a small 1 & 1/2 gallon batch. After a few days I stopped seeing activity in my airlock and added just a pinch of yeast energizer and the ferment ended up at 14% and the alcohol flavor is strong (I normally shoot for 9-10% to prevent this. I start my wines at 1.1 and stop at 1.03 or 1.02 this time it went to .99) so I'm planning on cutting it with apple and pineapple juice. These will likely be small amounts like a quart of apple and 16oz of pineapple. Which means ill have to convert volume to ounces (possibly quarts if I use 2 16oz pineapple) and will need to calculate the new ABV
How to do you stop that speeding bullet? I always use the amount of sugar I want for the final ABV and then allow the yeast to ferment brut dry and back sweeten. How do you successfully halt the yeast at 1.030? The colony size will be enormous and unless you are using indigenous yeast, they are not likely to be phased by K-meta.
 

Bmd2k1

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Given I'm making my first RJS BlackBerry Blast ....which has a BlackBerry Flavor blend to add post stabilized....

Got the same ABV ? Too....

Will know the ABV pre addition of blend....but ABV goes down based on Zero ABV addition. I suppose there's a ratio equation to solve...though the blend doesn't have any volume on it.

Cheers!
 

sour_grapes

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Given I'm making my first RJS BlackBerry Blast ....which has a BlackBerry Flavor blend to add post stabilized....

Got the same ABV ? Too....

Will know the ABV pre addition of blend....but ABV goes down based on Zero ABV addition. I suppose there's a ratio equation to solve...though the blend doesn't have any volume on it.

Cheers!

There is no law against, you know, measuring the volume of the blend pack. (See post #3 for procedure after that.)
 
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barryjo

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I am a firm believer in the KISS method. I use the Honneyman system wherein you take an OG, boil off the alcohol and reconstitue the volume, recheck for FG and use the chart to give ABV. More methods will be found at *fermcalc.com*. The process takes about 20 minutes. Most involve more math than I am comfortable with!
 
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BernardSmith

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Not sure that that is KISS but it is method of measuring the alcohol content of a wine directly , unlike using hydrometers which use density as an indicator for the sugar or the alcohol content as long as you know the starting gravity (density). Boiling off the alcohol present and replacing that with volume with distilled water allows you to more directly measure the alcohol content ... BUT you need to have access to the calculator as the math is not simple, is it? .
 

barryjo

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Not sure that that is KISS but it is method of measuring the alcohol content of a wine directly , unlike using hydrometers which use density as an indicator for the sugar or the alcohol content as long as you know the starting gravity (density). Boiling off the alcohol present and replacing that with volume with distilled water allows you to more directly measure the alcohol content ... BUT you need to have access to the calculator as the math is not simple, is it? .
I suggest you reread the process. The only math involved is subtracting the FG from the OG. Then looking up the conversion chart. And if you have previously copied the chart, it would be pinned on a wall next to the fermenter. Nearly all of the 20 minutes or so is devoted to the heating and cooling of the sample. Which is when I do my bottling.
And since water boils at about 212 degrees F., And alcohol at about 173 degrees F., an easy simmer is all that is needed. Reduce the volume by about half, cool and continue on.
 
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I am not 100% sure I understand the question, but here is an attempt to answer a question you MAY be asking! :)

Before backsweetening, you presumably know the ABV and the volume. Multiply those to determine the volume of ethanol you have. Then you add non-alcoholic ingredients. Now you have a new volume (but you have not added any alcohol). Divide the old ethanol volume by the new volume of the wine to get a new ABV.

Example:

You have 5 gallons of skeeter pee at 14% ABV. This means you have 5 gallons * 0.14 = 0.7 gallons of ethanol*. You then add 1 gallon of some simple sugar solution to your liking. Your wine is now 6 gallons total volume. Your new ABV is (0.7 gallon)/(6 gallons) = 11.7% ABV.

*To the expert reader: I am well aware that when you mix ethanol and water, volume is not conserved. That is WHY we specify ABV rather than some other ratio. However, that factor does not enter into this calculation because the beginning and ending results are similarly diluted.
Thanks for the explanation and simple example.đź‘Ť
 

winemanden

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Hmm! The jury's out on that one. If the ABV is too high she sees me through wine goggles and thinks I'm Tom Cruise. The trouble is at my age I'm no longer TopGun. I don't know who's most disappointed, me or her!:gn:slp:sl
 

sour_grapes

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Hmm! The jury's out on that one. If the ABV is too high she sees me through wine goggles and thinks I'm Tom Cruise. The trouble is at my age I'm no longer TopGun. I don't know who's most disappointed, me or her!:gn:slp:sl

Maybe it would make you feel better to realize that Tom Cruise is now 60 years old!
 

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