Lost track of ABV

I brewed a beer and 3 months later added 3lbs of cherries and a brett strain.  What would this add to a beer’s abv?  My only reading is my OG and I haven’t taken any others along the way.  Ballpark figure, or a rough idea of how I could get a more accurate reading in the end??

Approximately 1%.

Probably not much really. Fruit adds sugar but also volume. Often the added volume makes the result close to zero or sometimes it’s even negative. You could guesstimate by converting the brix of cherry juice and guessing how much juice is in 3lbs. Convert brix to SG and calculate a weighted average.

That’s actually quite good to know! Thanks man. I learned something new today…

Now that I’m on a computer I can type this out.

I asked the internet, and it says that sweet cherries have a brix ~20 (SG = 1.083), tart cherries are ~13 (SG = 1.053), and that 3lbs of cherries contain 1.25 quarts of juice. So you can see that sweet cherries will probably raise OG of most beers, though probably only a little. However, tart cherries added to a beer with OG > 1.05 will actually lower OG.

Calculate a ‘revised’ OG from this formula.

(Wort OG * Wort Volume) + (Juice OG * Juice Volume)
-------------------------------------------------------------      =    New OG of Wort + Juice
                  (Wort Volume + Juice Volume)

For example - tart cherry juice added to 5 gallons of 1.070 OG beer.

(1.070 * 20 quarts) + (1.053 * 1.25 quarts)        21.4 + 1.32
-------------------------------------------------    =  --------------  =  1.069
                    21.25 quarts                                      21.25

I’d call the cherries a wash for all practical purposes. I’d be more concerned with how far down the Brett takes it. I’d just take a gravity now and use your original OG measurement for calculating your ABV.  ABV equations are just estimates anyways, so this will get you close enough.

According to research we did for the book, sweet cherries have about 79 ppg and sour about 65 ppg.

What is ppg?

Points/lb./gal.  The number of gravity points you get from one lb. in one gallon.

Seems high  :-.…because as a comparative measure regular 2-row lends roughly 35 ppg, corn is about 36 ppg and sucrose (table sugar) is 46 ppg.

Sucrose is 46 points per pound per gallon, or the points yielded by dissolving one pound into one gallon of water. 2row would be the same I think. ppg only works for liquids. Although the abbreviations may get mixed up, I don’t know.

I know this to be fact; I read it on the internet.

There are 13 gr. of sugar in one cup of cherries.  I assume Drew extrapolated from there.

I believe technically its the SG when one pound of a fermentable is diluted to a total volume of 1 gallon. The SG of a solution made from 1lb of cherries topped up with enough water to make one gallon of solution is the ppg.

at that rate a gallon of cherries would only contain about .5 lb sugar or, if the sugar was perfectly extracted, about 23 ppg.

I’ll have to ask him where he got that number…

OK, I was misreading Denny’s post a bit. BUT - there is no way that whole cherries have a 79 points/lb/gal. That would mean 5lbs of cherries in 5 gallons of water would have an SG of 1.079 - no way. We’d all be making cheap cherry wine. But 79 points per gallon would be similar to 20 brix / 1.083 SG.

But I’ve been seeing ppg used for liquids and juices - points per gallon, and pppg used for solids - points/lb/gallon.

And yes, the gallon is the final volume.

My estimate of 1% accounted for the late brett addition and the fruit, assuming the original beer was going to have an FG of 1.010-1.012 before the brett and fruit.

Give the brett 2-3 months to finish.  FG should be 1.004 or less.