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Calculation of SO2 addition to must

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Vinoors

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As it relates to the calculation of SO2 addition for the must, I feel like I've come across conflicting information between 2 different sources- the More Wine Redwine Guide Manual & the Winemakers Answer book by Alison Crow.

-->Morewine Guide states that .33grams per 1 gallon equates to 50ppm.

-->Winemakers answer book states 50mg/L to "must or juice".

Using Morewine- 50 gallons * .33grams = 16.5grams of SO2

Using the Winemaker Answer book- 50 gallons * 3.785 = 189 liters
..189liters*50mg = 9450mg/1000= 9.45mg

1 calculation yields 16.5grams & the other is roughly 40% lower at 9.45grams.

Am I doing something wrong here?
 

GreenEnvy22

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Are you sure winemakers was saying to add 50mg? or did it mean to bring the level to 50mg/L ?
adding 16.5 g of kmeta to 50 gallons of wine/must will raise the level of free so2 by 50ppm (50 mg/L).

So if you were at 0 it would goto 50. If at 30 would goto 80.
I think you may have just misread what winemakers was saying.
 

Treeman

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They are saying the same thing, but just leaving out some details. Morewine guide is adjusting for the % of SO2 in kmeta being 57.6% by weight, and Winemakers answerbook is giving the amount of SO2 in ppm (1 ppm =1 mg/L). If you multiply the morewine value for kmeta x 57.6% you will get the same number as Winemakers. Since you can't easily weigh out SO2 gas, best to use Morewine calc.
 

Vinoors

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Interesting replies. I think what you are both saying makes sense. For better context, the winemakers book is referencing a range of "30-50mg/L of SO2 in the must stage". I assumed that SO2 = potassium metabisulphite powder, but now I realize that is where I'm wrong.
 

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