Alcohol level over time?!?

Peter Creasey

Peter Creasey

Peter Creasey
Does a wine’s age affect its level of alcohol?
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Dr Vinny (Wine Spectator) says...

No, it doesn’t. A wine’s alcohol percentage is determined during the fermentation process, when sugar is converted to alcohol. Once the fermentation process is over, the alcohol level remains constant.

But the way that the alcohol is perceived can seem to change over time. As phenolic compounds link and some of the wine’s primary flavors fade (and its secondary flavors become more prominent), there might be different points in the wine’s aging process in which the alcohol seems more or less pronounced.
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The answer I would have expected.

. . . . Pete
 
I also disagree with his conclusions. Ethanol has a lower boiling point than water (actually, ethanol forms a 95:5 azoetrope with water that boils lower than either). As the ullage of the bottle grows, the alcohol level should fall, albeit not by much. Esterification reactions will also consume a small amount of it, as will oxidation to acetaldehyde.

Mark Lipton
 
originally posted by MLipton:
I also disagree with his conclusions. Ethanol has a lower boiling point than water (actually, ethanol forms a 95:5 azoetrope with water that boils lower than either). As the ullage of the bottle grows, the alcohol level should fall, albeit not by much. Esterification reactions will also consume a small amount of it, as will oxidation to acetaldehyde.

Mark Lipton
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Mark,
This may be a red herring but could you comment on the premise that the perception of alcohol may vary over time?
Best, Jim
 
originally posted by Florida Jim:
originally posted by MLipton:
I also disagree with his conclusions. Ethanol has a lower boiling point than water (actually, ethanol forms a 95:5 azoetrope with water that boils lower than either). As the ullage of the bottle grows, the alcohol level should fall, albeit not by much. Esterification reactions will also consume a small amount of it, as will oxidation to acetaldehyde.

Mark Lipton
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Mark,
This may be a red herring but could you comment on the premise that the perception of alcohol may vary over time?
Best, Jim
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Jim,
That takes me out of my expertise. Given the fact that I've had wines that clocked in at 15% ABV and didn't taste "hot" and others at 13.5% that did, I think that his point is very likely true, though I say that as a wine consumer rather than a scientist. I've also heard others talk about the ability of dry extract to hide the presence of alcohol, including IIRC SFJoe, so there seems to be support for that statement.

Mark Lipton
 
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