UKH

Making Creme du Mure, where you soak blackberries in wine, strain, then add spirit and sugar. Three 75cl bottles of wine at 15% strength now has a volume of 4.1 litres with the juice of the fruit and sugar.  How much 40% spirit would I need to add to make the resulting booze 20% (20% being the number that I reckon stops booze going off)?

2.4 litres ?

My long winded method I’ve just tried gave 2.25 litres for 19.5%, so I reckon ‘yes’.  Ta

My method has clearly gone a bit wrong, because most recipes say you add about one glass of spirit for each bottle of wine, not one bottle of spirit for each bottle of wine. My blackberries (and a few elderberries) must have been super juicy! I will end up with about a gallon of the stuff. 

Or they're aiming for less than 20% end result. Aiming for 10% gives you 242ml spirit. 15% needs 1110ml. Assuming a 125ml glass of added spirit, it looks like they're aiming for just under 11%.

My utter guess would be:  this bbc recipe involves mashing the berries, pouring over a bottle of wine, straining and adding sugar. This would increase the volume quite a bit. Adding a glass of booze probably brings the % alcohol to back where you started. I’m aiming to make a ‘keeper’. Anyway, I added a bit more spirit for good measure. Will have a sip later and post back. I’ve got over 6.5 litres. 

(2.25 * 0.15) + (X * 0.4) = 0.2 * (4.1 + X)
Rearrange for X

0.82-0.3375 = X * (0.4 - 0.2)
X = 2.4125 L

But cheap alcohol is usually 37.5% and I'm not sure 20% is the magic number. I would think the fermentation process for Port kills off bacteria before the spirit is added. I put prunes in sweet wine and just checked - all seems fine, so probably no hard and fast rule.

For future reference, if relevant, you can get navy strength or export strength spirits for things like this. I use 58% gin for my slow gin - it keeps the % alcohol over 40% afterwards.

Thanks for the equation, will save it. 

What’s the prune drink - sounds interesting  

Don’t tell anyone, but my mate Mick made a load of homemade moonshine that was 63%, diluted to 40%. That’s what I’ve been using. 

Nigel Slater's Christmas Chronicles has 3 drinks at the start. I've been trying these each year, as well as my usual Spiced Arancello (what I use to soak fruit for christmas cake, mince pies).

https://www.bbcgoodfood.com/recipes/spiced-arancello
 

#1 Apricot, orange, star anise, brandy, sugar, sweet white wine

#2 Fig, anise, vodka, white wine, maple syrup

#3 Prunes, sultanas, muscat / moscatel

Soak for a while and then use the fruit in something (cake, or just fold into some chantilly cream). Drink the liquid as a Christmas drink.

I'm putting the prunes into a plum pudding.

I found that leaving the fruit in blackberry vodka resulted in bitterness, which I took to come from the seed pips. I decided in future to mush the blackberries, steep for a while to leach our the fruit juices, and then strain & bottle.

I thought this was a thread where you got pissed and then did Maths.  Disappointed ; )

Didn't add up for me either. But I did take away something. 

More constructive...

Rumtoft. Or similar. Always a winner. Just don't drive after a bowl of the fruit. You'll be calculating number of pints of water after a 2nd helping!