figuring total mass of must

I have two types of grapes. 500 lbs of cab sauvignon and 518 lbs of cab franc. When we crushed this we came up with 55 gallons of cab franc must and 75 gallons of cab sauvignon must. Why the difference? It doesn't make sense to me. We had less weight of the cab s than the cab franc. Doesn't make sense.
Thanks

One grape just contained more juice than the other. Might of been one got more water than the other, maybe just the kind of grape has more juice than the other. Any kind of weather conditions could change the amount of juice in the grape. Lots of things could cause this. Arne.

Arne said:

One grape just contained more juice than the other. Might of been one got more water than the other, maybe just the kind of grape has more juice than the other. Any kind of weather conditions could change the amount of juice in the grape. Lots of things could cause this. Arne.

Click to expand...

That was my initial thought as well. But wouldn't the water content impact the weight?

Could be seed size, skin thickness, all kinds of things could add to weight while taking away from juice content.

Smaller berries, with a much lower juice to skin/seed/stem ratio could be the difference there. Were your cab franc berries notably smaller than your cab sauv berries? I agree, 20 gallons is a big difference. If the cab franc berries were bigger, I'll be totally befuddled.

If all you did was crush them and remove the stems, the stems are vastly different, or it's a mystery. Assuming the stems are about the same, I agree, it doesn't make much sense, since the seeds, skin, pulp, and juice are still present. Notice how I used sense and since correctly right there together?

Maybe you were just getting tired when you got to the Cab Franc and weren't squeezing as hard? (jk) My guess is that the franc had less water to skin ratio. A rain right before harvest can really plump those baby's up! I just love science.

If they were just crushed and not pressed, then squeezing is not relevant.

Absolutely. Water weighs ~8lbs/gallon. Plus The QA/QC on those at harvest is not all that great. The workers have to pick fast, the packers have to pack fast, time is $$$$.

Boatboy24 said:

That was my initial thought as well. But wouldn't the water content impact the weight?

Click to expand...

Yea, I still don't know what happened. We have a lot more cab s must than cab franc. Only 18lbs difference. Well I'll maybe figure it out after I press. Right now though, fermenting is going great and have added Malolactic bacteria in the last two days after checking the free SO2. Must is at 72 degrees plus and lots of good color and the aroma is fantastic. Grandsons helping push the cap down and enjoying all. Will check brix maybe tomorrow to keep an eye on it. Have to go to the hospital tonight to see my new granddaughter

You may find that after you press, they are much closer in total gallons. Time will tell.

Well we just pressed today. Out of both musts, we got about 42-45 gallons of wine. There is quite bit of sediment involved so I'm thinking we'll lose about a carboy per batch of musts. With 55 gallons of cab franc and 75 gallons of cab S must, we still got pretty close to the same amount after pressing. I'm thinking it was the size of the fruit, cab sauvignon, due to the larger amount of must volume. All in all it turned out to be pretty good day. Got a 60 gallon oak barrel filled with 30 gallons merlot, 20 gallons syrah, and 10 gallons malbec. Hope its going to be a good blend. Plan on bottling next September so as we can put next years in the barrels.