I recently brewed a cream ale and added 5 lbs of blackberries to the secondary. The base ale came in right around 6%. The recipe calculator I use did not adjust the ABV to include the added sugars from the fruit addition. Seems to me the addition of that much fruit would boost ABV to some degree. Also, I was listening to a podcast recently that suggested to add sugars to the secondary to further boost alcohol.What is the best way to calculate/estimate the final ABV when adding fruit or sugar into secondary?
Sugar adds about 45 ppm, meaning one lb. in one gal. adds 45 gravity points. Fruits differ. We have a chart of average fruit ppg in Experimental Homebrewing and I’m sure there are sources online. We list blackberries at 40 ppg. Which seems high when I think about it.
So the addition of 5 pounds of blackberries to 5.5 gallons would be near 40 ish gravity points total? If the gravity of the cream ale was 1.013 when blackberries were added that would bring it to 1.053 or there abouts? After the fruit is completely fermented, the difference from now until then would be added to final ABV? Or am I wrong?
You’re correct assuming our number is correct. I looked around and now I think it’s right, although it seems really high.
It seems very high. Given those numbers, 1.053, and assuming it would finish at or near the cream ale 1.013 +/- it would add 5-6% to the original ABV?
My hydrometer after adding the blackberries only reads 1.018, not sure how accurate this would be given the sample is only the liquid, none of the solids from the puree. If this was accurate, and it were to finish at the original 1.013 it would be about .66% alcohol added to the original 6% Of the base cream ale, correct?
According to the USDA, 100g of blackberries contain about 5g fermentable sugars, i.e. they are 5% sugar. Assuming the berries were well-macerated and all that sugar is available to the yeast, your 5 lbs should thus be the equivalent of 0.25 lb of glucose. Plug this value into your recipe and you’ll get an idea of the alcohol the berries contribute.
https://fdc.nal.usda.gov/fdc-app.html#/food-details/173946/nutrients
This actually seems a bit closer to my actual measurement, assuming again the blackberries ferment to at or near the gravity of the base ale.
By my calcs, I believe blackberries yield 2.1 2.3 ppg (when using sucrose as the reference standard)
That sounds about right to me. I know when I add blackberries to a high gravity mead must, it actually lowers my gravity because of dilution rather than increasing it.
Unless you are able to do a distillation analysis it is just going to be a close guess. Even the packaged aseptic purees give a range.
Absolutely. It’s an agricultural product with different varietals, growers, and growing seasons. Variability should be expected.