ABV Does Not Match ABV in the Brewing Classic Styles Book

• • SVA Brewer With Over 50 Brews From United States of America
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Hi ya Scott ,

You'll see in the BCS book, just under the OG and FG, a thing called "ADF". This is short for 'apparent degree of attenuation'. Basically, this means how much of the 'sugars' in your wort your yeast will be able to eat up and convert to alcohol and CO2. In the book it lists an ADF of 81%. You need to type that 81 into Section H as follows...

2015-08-30_19-19-36.jpg

Unless you type a figure in that field, the BIABacus assumes a very reasonable 75% ADF or 'apparent attenuation' and this will usually server you well. In fact, I think the 81 is a little high for the yeasts suggested.

Attenuation also depends on many factors apart from the yeast used. [EDIT: I just saw that Josh has alluded to this above]. It's a complex area and not one to get really worried about.

One final question you might have is that even after typing in 81 into section H, the BIABacus only reads out 5.0% ABV not 5.1%. This will be basically due to some lack of precision in the info supplied. For example, go to Section R and type in 1.0085 as your actual final gravity type in 81.4 into Section H and you will get matching answers for ABV. (You'll still have a 0.1 discrepancy on ABW though and this will most likely due to the ProMash formulas not using as many decimal places as the BIABacus in their basic formulas.)

Also have aread of this post on Number Respect and Disrepect


PP

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