Alcohol Content - which method is best?

[BrewerBlue]

Greetings all,

Just wondering what method for computing alcohol content on a finished beer everyone is using. Gravity measurements? Lab Services? Ebulliometer readings? Others?
How accurate is each one and which ones are accepted by the government?
Thanks in advance.

[jipjanneke]

Lab might be 'best' in terms of accuracy, but not necessarily value or convenience.

In Australia, it depends on the volume of your production, and therefore the size of your brewery and your brew schedule, and therefore the size of your market. Up to 100,000L per annum you are permitted to simply calculate ABV via gravity difference via hydrometer. They don't stipulate a formula you must use - they just say that you need to use the formula that gives you the "correct result "(whatever that may be!) I reviewed the results of a few and chose one by Noonan, that seemed to give me the least ABV (and therefore least tax to pay). Probably, the tax office would require this to be checked against a lab test to prove the result, and then you would be ok. Haven't got around to this check yet.

Does anyone else have comparisons between lab results and various formulae based on gravity difference?

I found this method to be cheap, simple and instant. Just needed a hydrometer and thermometer. I have a formula for correcting gravity with temperature if you need it that worked well. How accurate it was, I'm not sure but it must have been ball-park and also good enough for the normal requirements of the tax office for a small brewery.

Once production volumes increase, the requirements change. Breweries producing more than 100,000 litres of beer per year are required to use approved measuring equipment for establishing the strength of their brews.

This equipment includes:
• gas chromatography
• near infra red spectrometry, and
• distillation followed by the gravimetric measurement of the distillate or by measurement in a density meter.

An independent approved authority must periodically calibrate measuring equipment.

So, this starts to get quite a degree more complex.

Don't know what the rules are in the US but some of this might give you a start...

[Sir Brewsalot]

Hydrometer with directional sense-check with my liver.

[Ted Briggs]

Drink 4 pints then drive to the nearest police station and ask for a breathalizer! ;)

[James Murray]

Starting Gravity minus Finishing Gravity multiplied by 105 multiplied by 1.25 will give you the ABV

[jason.koehler]

We use Brix, it's fast, easy, and doesn't require much time or equipment to do.

[Greenbrewmonkey]

Hello,

The methods jipjanneke suggested that the larger AU breweries must use would give you the greatest degree of accuracy. You can find labs, such as Brewing and Distilling Analytical Services (www.alcbevtesting.com), that will do all the heavy lifting for you.

BDAS is now fully TTB certified if that helps.

It is my understanding that the TTB only requires alcohol statements on malt beverage labels if they are required by state law. Many states don't require it, so you may not need to include it on your labels. If you do, the TTB requires that the stated alc. content be within 0.3 % of the stated value. I.e. 5% could be from 4.7% to 5.3% (wiggly room!) Last time I checked they didn't specify how it was to be determined, just that it was accurate.

Cheers,
Ron
Jolly Pumpkin Artisan Ales