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.
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.
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.