Must to juice volume calculations

[LeChat]

Hey there,

I am trying to figure out how much acid I need to add to my must to correct it. I have about 44 gallons of juice and grape skins from 432 lbs of grapes that I need to raise by about 4 g of acid per liters.

My question is as follows: do I adjust based on total volume or do I allow for some skin volume in there?

I have very rudimentary tools (TA test kit and hydrometer).

Thanks!

 

[Boatboy24]

I usually estimate 2.5 gallons of wine from a 36lb lug and would adjust based on liquid volume.

 

[LeChat]

Thanks Jim!

I have also found a site that says that 65% of the total volume can be assumed to be juice as a rule of thumb.

 

[salcoco]

12-15 lbs of grape will equal one gallon of wine. I use this calculation in all of my additions for the last 30 years without failure. Use 15 to be cautious. yours would be about 28 gallons. I would add only half the amount of acid stated and test again. I suggest you add only half now wait till fermentation and clearing is complete taste the wine and then add more acid if needed. also suggest purchasing a PH meter it usually more important that acid measurement.

 

[JohnT]

My approach is this.... Unless you filter your must before performing a TA test, your test result can not be accurate. So much of must is pulp, etc, that I figure on my readings as being lower than they actually are.

With this in mind, I adjust to a minimum of .58 gpl (if needed) then adjust again when fermentation is over and the wine has cleared somewhat.

Given your total weight, you can expect about 30 gallons of must. Adjust to that figure.

 

[sdelli]

I have played with this quite a bit.... I come up with that you usually get about 10% return of must from a crush.... 500 lbs. of grapes will give you 50 gallons of must. You then usually get between 6% to 7% return from grapes to juice...... Same 500lbs of grapes will yield 30 to 35 gallons of wine depending on your press..... This has always been real close.... As far as raising acid.... I always calculate by the amount of must I am dealing with.... Not the projected amount of juice.


Sam

 

[LeChat]

Thanks for all the feedback.

Regarding acid, I will likely adjust based on taste. I am dealing with central valley grapes which are naturally lower in acid and higher in PH. I have adjusted the must somewhat and will be adjusting based on taste after pressing.

I will likely add as much acid as taste allows and PH should be in the "comfort" zone.