Sulfite for Grapes

[s0615353]

When working with 100% fresh grapes, do you add sulfite upfront for the amount of wine it will make, or for the amount of must that is in the fermenter. For example, 80 pounds of grapes is about 12 gallons worth of must, but it produces about 4-5 gallons of wine. To bring it up to 40 ppm before pitching the yeast would I add 1/2 tsp (for the 12 gallons of must) or a little less than 1/4 tsp (for the 4-5 gallons of wine)?

Thanks as always for any help!!!

 

[ibglowin]

Its normally calculated on the total volume of the must. Easiest thing to do is prepare a 10% solution of Sulfite. 10 grams in 100ml of water. Mix well. If you want 40ppm of sulfite in the must and have 12 gallons of must the formula is then 12 X (0.70) = 8.4ml If you want 50ppm the factor is (0.88)