Can I test total alcohol after fermentation is complete?

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Rice_Guy

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* there is a tool called a Vinometer that claims to do it. Mine sits on the shelf. JC, Purple Foot had the device.
* testing labs will run this in a lab, ATF wants a lab number for commercial wine so a lot of labs can do it.
* if you know the starting must gravity and finished wine’s gravity you can calculate the number. If you know what went into the recipe and finished gravity again you can do a mass balance and calculate.
 

cmason1957

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You can find someone who has an Ebulliometer, (approximate cost $1,000 US). I believe they are considered accurate enough for the TTB.
 

BernardSmith

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Here's a very low tech and inexpensive method of measuring the alcohol content of a wine or mead whose OG you don't have. It is inexpensive but it does require that you sacrifice a small amount of your wine.
1. Record the current SG of your wine (or mead).
2. Pour a known volume of your wine, say 200 ml, into a beaker and boil the wine until it is down to half. In this example, 100 ml. Alcohol boils off first and with this amount boiled off you will have boiled off 100% of the alcohol in the wine along with some of the water.
3. Replace the lost volume with distilled water and measure the SG.
4. Subtract the first SG from the second SG and apply this number to the calculator at https://www.musther.net/vinocalc.html#spiritindication
So, for example, if your initial gravity was 1.000 and your second reading was 1.015 this would be 15 and the calculator will show that 15 is equivalent to an ABV of 11.4%
 

Johnd

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Since alcohol boils at 173.1°F, could one heat a measured quantity of wine to 180°F for a some period of time sufficient to boil the alcohol off, then measure the difference in the before / after volume, then calculate the ABV?
 

cmason1957

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Since alcohol boils at 173.1°F, could one heat a measured quantity of wine to 180°F for a some period of time sufficient to boil the alcohol off, then measure the difference in the before / after volume, then calculate the ABV?
Isn't this, essentially what an ebullometer does? I've never used one, but I know it has something to do with a measured amount, boil off, then measure again.
 

sour_grapes

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Since alcohol boils at 173.1°F, could one heat a measured quantity of wine to 180°F for a some period of time sufficient to boil the alcohol off, then measure the difference in the before / after volume, then calculate the ABV?
Isn't this, essentially what an ebullometer does? I've never used one, but I know it has something to do with a measured amount, boil off, then measure again.
No, no, not quite right. For @Johnd, the problem with your scheme is two things. First, the "boiling point" of a solution depends on the composition, so it is not the case that ethanol "boils" at 173F regardless of what solution it is in. The second thing is that you will also be evaporating water during the time at 180F. I think this will become obvious to you if you were to heat a pot of water to 180 and then, say, hold a cool glass of water above it. You could dry out your entire sample at 180F if you waited a while.

And Craig, not quite. IIRC, an ebulliometer measures the temperature at which a solution starts boiling. The boiling temperature depends on the composition, allowing the ABV content to be inferred.

I have never tried it, but I think @BernardSmith 's suggestion is a good one.
 

Johnd

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No, no, not quite right. For @Johnd, the problem with your scheme is two things. First, the "boiling point" of a solution depends on the composition, so it is not the case that ethanol "boils" at 173F regardless of what solution it is in. The second thing is that you will also be evaporating water during the time at 180F. I think this will become obvious to you if you were to heat a pot of water to 180 and then, say, hold a cool glass of water above it. You could dry out your entire sample at 180F if you waited a while.
I assumed some water would be lost as well, but there must be a temp at which the alcohol comes out leaving most other liquids behind, or distilling wouldn’t work. Certainly, it’s not pure alcohol being produced. Guess with such a small sample size, even a little water loss would skew the results.
 

winemanden

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My thoughts on this, does it really matter as long as your wine tastes good.
I know someone will shoot me down on this, but there you go.
Regards.
 

cmason1957

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This is the part I absolutely love. I aced HS & college chemistry, and the laboratory work is very satisfying to me.
Back when I was in HS and College, I did my best to avoid the Chemistry classes. Too one in both places, got my B and ran away. I had to think to much for those classes and that interfered with drinking and back then, we just couldn't have that nonsense.

My thoughts on this, does it really matter as long as your wine tastes good.
I know someone will shoot me down on this, but there you go.
Regards.
I am with you, it doesn't really matter almost that much to me.
 

sremick

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My thoughts on this, does it really matter as long as your wine tastes good.
I know someone will shoot me down on this, but there you go.
I'm with you, that's why I'm not willing to spend any real money on testing equipment. The APV amount has 0 bearing on anything I do, how I make my wine, or whether it gets drunk. I know it's tradition to put it on the label, but how many people are like "oooh that's a 14% APV wine, I never drink anything above 13%". I will not be selling my wine commercially.

As long as the SG shows that fermentation is done, I'm good.
 

Rice_Guy

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The food drug and cosmetic act required this tradition, , 1910 or so
it's tradition to put it on the label,
As long as the SG shows that fermentation is done, I'm good.
I tend to agree with who cares? as @Cmaison @sremick. The label requirements give a 2% error level. The tax break is below 8% ABV. We are not commercial entities . . . 200 years ago we didn’t have the technology to ask the question . . . . Gosh I am sounding like an old fart now , ,
 

BernardSmith

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I think the question is a good one from a purely scientific perspective: can you determine the alcohol content of a sample of an unknown wine? and the answer is , yes. Is that something you need or want to know? Only you know the answer to that question. But you don't need to spend $100 or $1000 on finding the answer to the first question.
 

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