Quincer
New Member
Is there a way to test the alcohol content of your beer?
Alcohol Content?
- Thread starter Quincer
- Start date
Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:
Not really to "test" it, but it's very easy to do. You take the original gravity of the wort, and subtract the finishing gravity, and just multiply it to get a good estimate of the final alcohol by volume (ABV) percentage.
The actual formula is (OG-FG) x 131= ABV.
The actual formula is (OG-FG) x 131= ABV.
Welcome to HBT!
I know what the alcohol content in my beer is because I make it and I take readings. What is it you are trying to find out? Are you questioning a particular beer you made or wondering about beer in general.
I know what the alcohol content in my beer is because I make it and I take readings. What is it you are trying to find out? Are you questioning a particular beer you made or wondering about beer in general.
llazy_llama
Well-Known Member
Drink 12 of them, then write a letter to an old friend you haven't talked to in years or an ex-girlfriend. The next morning, if you have that "oh hell, what did I do???" feeling, you'll know.
On a serious note, if you head down to the Brewing Software section of this forum, and download Beersmith, you should be able to plug in your recipe (assuming you know the OG, FG, and a few other key points) and get an estimate. If you're staring at a batch of finished beer now, with no recipe on hand, it may be too late. I'm sure there's a way to find out, but it's probably not time/cost effective.
On a serious note, if you head down to the Brewing Software section of this forum, and download Beersmith, you should be able to plug in your recipe (assuming you know the OG, FG, and a few other key points) and get an estimate. If you're staring at a batch of finished beer now, with no recipe on hand, it may be too late. I'm sure there's a way to find out, but it's probably not time/cost effective.
Quincer
New Member
Exactly the reason I was asking.
If you post the recipe you used, we could probably give you a really good guestimate.
winzerz
Well-Known Member
well IF you had access to a refrigerated centerfuge and a gas chromatograph
you could find out exactly how much was in yer beer
but what are the odds of that lol
:rockin:
you could find out exactly how much was in yer beer
but what are the odds of that lol
:rockin:
That's funny... is it honestly that easy??
What a jerk I am... For the last few years I've been calcing Alcohol By Weight and then using that to do ABV.
ABW = 76.08*(OG-FG)/(1.775-OG)
and then...
ABV = (ABW*(FG/.079))/100
Luckily I had it plugged into an Excel spreadsheet so all I ever did was just type in the OG and FG... but I still feel stupid.
:cross:
yes, it's that easy. I'm mathematically challenged, so I don't do any difficult calculations. Even I can do this one.
Ok... when I do the simple way on the "way, way, way over the top Utopia clone" thread OG/FG of 1.160 and ,1.040 (current... not final)
... I get 15.7%
When I do my crazy super-cmoputer method, I come up with 19.4%... apparently my super computer method is way off??? That's weird because intuitively, all of my beers for the last few years always SHOULD be and taste like the ABV's that I've calced using that long way.
... I get 15.7%
When I do my crazy super-cmoputer method, I come up with 19.4%... apparently my super computer method is way off??? That's weird because intuitively, all of my beers for the last few years always SHOULD be and taste like the ABV's that I've calced using that long way.
If you have a precision scale, it's fairly easy. Add exactly 100 grams of brew to a small jar. Heat the jar in a waterbath at 180F. Monitor the temperature of the beer, when it goes over 175F all of the alcohol is gone. Weigh again. The difference is your percent alcohol by weight.
remilard
Well-Known Member
A couple of points:
None of these formulae are going to be exact, they are approximations.
Gas chromatography is indeed in the best way to measure this and so we generally prefer approximations that can be performed with a number of hydrometer readings.
I believe the Cape Brewing approximation is better than the 131 approximating however I think Cape Brewing is doing it wrong. In the numerator you ought to be subtracting the real final extract and not the apparent final extract. Also this ought to be performed in degrees plato not SG terms.
The two approximations ought to agree quite closely if the Cape Brewing approximation (due to Balling) is being used correctly.
Here is an HBD post from George Fix on the Cape Brewing method.
HOMEBREW Digest #880 Wed 13 May 1992
Note that Fix claims that the Balling approximation is subject to error as large as 3%-5% (percent error, not in absolute terms) and the 131 approximation is a bit rougher.
None of these formulae are going to be exact, they are approximations.
Gas chromatography is indeed in the best way to measure this and so we generally prefer approximations that can be performed with a number of hydrometer readings.
I believe the Cape Brewing approximation is better than the 131 approximating however I think Cape Brewing is doing it wrong. In the numerator you ought to be subtracting the real final extract and not the apparent final extract. Also this ought to be performed in degrees plato not SG terms.
The two approximations ought to agree quite closely if the Cape Brewing approximation (due to Balling) is being used correctly.
Here is an HBD post from George Fix on the Cape Brewing method.
HOMEBREW Digest #880 Wed 13 May 1992
Note that Fix claims that the Balling approximation is subject to error as large as 3%-5% (percent error, not in absolute terms) and the 131 approximation is a bit rougher.
remilard
Well-Known Member
Not all of the alcohol will be gone, just like not all water is gone once you have heated it to 100 C. Confounding the issue is that water dissolves alcohol extraordinarily well. Also some of the water will have evaporated.
Empirical evidence suggests that alcohol in beer can not be reduced much more than by half in a household kitchen. Mary Beth Raines posted about this on HBD. Nobody but her appears to have ever performed this experiment and actually measured the result and then written about it publicly.
Quincer
New Member
I didn't realize the recipe had the ABV. It's 4.0% to 4.5%. A little vague but close enough. Thanks for your help.
American Light
3.3 lbs. Plain Light Malt Exract
1 lb. Plain Light Dry Malt Extract
1 lb. Rice Syrup Solids
1 oz. Sterling Hops (Bittering)
1/4 oz. Sterling Hops (Finishing)
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