Salut/Hi Mark Lipton,
le/on Sun, 26 Sep 2004 02:37:30 GMT, tu disais/you said:-
>Ian Hoare wrote:
>
>> By the way, as you understand it, what's the opposite of "reductive"? We had
>> a long debate here ages ago, about the way in which wines age. Given that
>> alcohol oxidises pretty quickly, thereby using up any free oxygen in the
>> ullage, isn't most of the life of a wine under reductive conditions, even
>> under cork, expecially when some sulphur dioxide (metabisulphite/camden
>> tablets) is used at bottling time.
>
>With all due respect, Ian, sulfite will oxidize far faster than alcohol.
Sorry not to have expressed myself clearly, Mark.
That's exactly my point. Even though oxygen may have been present in the air
space between cork and wine, the SO2 usually added at filling time will have
neutralised it very quickly. So from then onwards, the fact that you have
alcohol (and perhaps still some free SO2) present, and no oxygen, means that
the conditions in the bottle are reductive rather than oxidative. The only
chance of any oxygen getting in would be when the bottles cool (normally
during fall and winter, in a non temperature controlled cellar). And even
then the minute traces of oxygen (w/w when compared with gram-mole
equivalents of alcohol) would be used up _relatively_ fast, returning the
conditions in the bottle to reductive.
>Indeed, if the oxidation of alcohol weren't very sluggish, our opened bottles
>of distilled spirits would be too vinegary to drink.
Good point. I'd not thought of it. I can only suggest that either the much
higher levels of alcohol present inhibit oxidation or that the weight (in gm
moles) of oxygen is so low that the oxidation is negligable. Because we all
know that once a bottle has been opened and decanted, a time bomb is
ticking. While the wine nearly always improves at first, this improvement is
time limited (15 mins to 48 hours in most cases) and then it deteriorates -
except in the case of a very few wines (Tokaji Aszu, Madeira to name two).
Would you contend that the deterioration is more due to oxidation of
complexes other than alcohol? Possible, certainly. But that would apply as
much to oxygen present in the ullage. And whether it's alcohol or some
complex that oxydises, it will absorb the free oxygen - thereby returning
the equilibrium to reductive.
> As for "reductive" flavors, I'd suggest thiol odors (rotten eggs, skunk, rubber, etc.) as the most
>recognizable.
And in the case of strongly reductive conditions, these faults HAVE been
recognised, certainly. But coming back to the central point, I'd be
astonished if the presence of cork closures (as opposed to something more
hermetically perfect) would significantly reduce the incidence of this. What
do you think?
Good to see you posting again!
Our best to Jean.
--
All the Best
Ian Hoare
http://www.souvigne.com
mailbox full to avoid spam. try me at website