dave45 wrote:MKG wrote:I hate to say this (I really HATE it) but alcohol can be driven off by raising the solution above 70 degrees C for ten minutes or so.
Mike
ethanol's boiling point is 78 C.
So I built a digital thermometer controlled heater and raised the temperature of some scrap wine to exactly 78 C. Then 79C etc thinking that all the alcohol would boil off neatly.... but .... it aint so simple.. azeotropic mixtures get involved... We didn't do this in O-level chemistry. Why don't they teach you useful stuff at school.?
Very true, Dave, and well spotted - 80 degrees would be quicker. I must admit I was thinking in terms of minimum flavour alteration, which wasn't so appropriate for this question. However, vaporisation begins at an appreciably lower temperature than the overall boiling point (defined as when vapour pressure is equal to ambient pressure throughout the BULK of the containing medium). Think of heating a pan of water - you can clearly see vapour rising long before boiling point is reached.
Oh - and stills are run at the boiling point of alcohol, not water - but you still get water vapour produced (hence the reason distilled spirit is never 100% ABV).
Mike