There is a good article on wikipedia http://en.wikipedia.org/wiki/Alcohol_by_volume
I states there are 2 methods of calculating the ABV and Iwas curious to know which wa sthe prefered method for the small craft brewer. maybe someone can let me know.
Where 1.05 is number of grams of ethanol produced for every gram of CO2 produced and .79 is the density of ethanol alcohol,
However, many brewers use the following formula:
- ABV = (Starting SG - Final SG) * 131
to be honest, most of them have a program that runs this calculation for them. As long as you have a hydrometer or a refractometer you can measure the starting and final gravity. Plug those into a program and it runs it for you.
ReplyDeleteThe other thing to keep in mind is temperature. To get an accurate starting/final SG, it has to be taken at 60 degrees F. So if you take your original gravity reading when the beer is still 100 degrees and your final gravity of the cold beer at 40 degrees, then your numbers will be off.
Again, there are simple programs that will adjust your readings based on the temperature and then calculate the ABV for you. I use BeerSmith for homebrewing, but there are also plent of free, online calculators like the one at http://www.rooftopbrew.net/abv.php
All that being said, I, as a homebrewer, use the 2nd formula if I calculate by hand, but craft brewers very well may use a different one.
Actually, here is a pretty cool site that does that calculation, as well as many others for you. Again, this is more on a homebrew scale, but I'd image it could be used for a production brewery as well.
ReplyDeletehttp://beercalculus.hopville.com/recipe
Thanks Chris for the info
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