calculating alcohol when using fruit pulp.

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helluvatractor

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Hi all.
Could someone explain in simple terms. How to calculate the potential alcohol when using fruit pulp / carton grape juice / sugar ?

Here's my scenario:

Been given a load of plums, so am roughly following the recipe for Victoria plum wine in the boots book. But stepped up the quantity to make 5 gallon.

So far, I have used 12.5 kilos of fruit , poured on 6 l boiling water, mashed it all up and its fermenting nicely. In four days I intend to strain, add 5 l of supermarket grape juice , and (I think) 5 kg sugar (depending on whether I can work out the potential alcohol ).

So, this is what I need to know - how much alcohol per gallon is this ammount of fruit pulp likely to produce ? How much could I expect to lose when I strain and then later rack off the lees ?

If I know this, then I can work out how much extra sugar the grape juice will add, then finally how much actual sugar I need to add to make a wine with the alcohol I desire.

Many thanks in anticipation
 
Sorry. I just read moleys posts, (should have done this first) !

and I think I am sorted now. unless i have got it wrong -

plums have about 10% sugar, so 12.5 kilos will yield about 1.2 kilo sugar . With an estimated 90% extraction , ( does this mean after straining ?) it will come to about 1kg sugar per 5 gallon or 200g per gallon.

adding 5l of grape juice will add 850g per 5 gallon or 170g per gallon.

so before i add any sugar each gallon would have 370g of sugar (whether its still sugar or alcohol now). giving a potential alcohol content of 4.4% (if i added no more sugar).

obviously, i want a higher alcohol than this, say 11-12%, so i would be looking at adding approx 615g per gallon or 3 kilos per 5 gallon.

phew, thats the most maths i've done since school. please, anyone feel free to correct me if i've made a mistake along the line
 
You have 5kg plus 50g sugar in 5 gallons. Thats just over 1kg per gallon, which gives you about 11% by my reckoning. Victoria Plum wine is usually made a bit stronger as it benefits from some residual sweetness.
 
My blackberry wine, for 5 gallons, I put in 8kg of fruit & 6kg of sugar.
From this I get 14.5%

I've done plum before, which I've used less fruit than you (1.8kg per gallon) & added 400g of honey, with 1kg of sugar
This got me 13.5%

So I reckon you'll get something around that
 

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