applejack

Read a post a few nights ago about freezing wine and pouring off the alcohol. The legality of this was also discussed. Let's say a friend of mine at an undisclosed location tried this. He froze bad wine to a heavy slush and drained off that which didn't freeze. He checked the SG against the OG of the wine when he made it. The SG had gone up over the final gravity reading of the wine. It makes sense, removing the water would make the liquid more dense.
Now for the question : How do you measure the alcohol level for something done in this way ? Could you take the FG of the wine and compare it to the SG of the strained-off liquid and do the math in reverse?


Help!!!!!

Hypothetically speaking, I (still) don't know.

Supposing you had your initial sg figure and the sg of your final product you could figure your end ABV%.

Here's a good read for you:

http://www.themadfermentationist.com/2009/07/testing-alcohol-content-of-ice.html

Finished first batch! [emoji3]


View attachment ImageUploadedByHome Brew1452138605.611137.jpg

Looks tasty

Well, kind of a necro thread but to answer the original question, I'd think you could approximate it by knowing ABV, total volume before, and total volume after. You can calculate volume of alcohol, and if you assume you remove only water (which isn't actually the case, you'll remove other stuff and some alcohol as well, hence why I say "approximate") you can then convert that back to ABV. Say 5 gallons of 7% cider, that's 0.35 gallons of ethanol. If you remove 1 gallon of water, the 0.35 gal ethanol then becomes 8.75%.

There's data out there on how much water will freeze out at various temps but I have no direct experience. But if you don't have the equipment that AJ DeLange has (via the TMF link above), that's the route that I would go.