Calculate abv after fruit additions

[bedman]

So I brewed a straight up American wheat. Og was 1.051. Transferred to secondary at 1.009 on top of vintners harvest blueberry fruit purée (49oz at 1.032-1.057 og) and blackberry fruit purée (49oz at 1.036-1.057). FG after 2 weeks of secondary was 1.006. Math slays me. I know I won't get the abv exact since I don't know the exact OG of the purées but I would like to know the range it might be in. Thanks! I may name it Barney Blood due to it looking like cloudy purple kool aid.


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[bedman]

Any idea?


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[pdxal]

If you assume 1.051 from the range of gravity for the purees you listed the ABV would be the same. Regardless, the effect will be negligible for 98oz of similar gravity liquid into a 5g batch.

http://www.themadfermentationist.com/2010/10/adding-fruit-to-beer-increases-alcohol.html

 

[Beernik]

Yeah, the problem with adding fruit is that you don't get net much, if any, additional alcohol because you are also adding water with the sugar.

Whole fruit is roughly 10ppg. If you are adding more than one pound per gallon wort, you aren't significantly affecting the ABV of a beer. Fruit purée has a greater ppg, but it's still not enough to raise the ABV much.

And when you run the calculation, it doesn't matter if you assume you add it before or after primary fermentation is complete. It works out to the same value either way.

 

[bedman]

Wow. That makes so much sense. I feel enlightened yet moronic. Haha.


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