On 4/12/12 2:56 PM, RichD wrote:
> On Apr 11, Mark Lipton > wrote:

>> Not at all. Many reactions that take place in the bottle are
>> desirable.
>> To use the most obvious one, the cross-linking of tannins
>> (by at least two different pathways) leads to the reduction
>> of astringent flavors in red wine
>
> Elaborate please.
> We're talking anaerobic, right?

Both aerobic and anaerobic cross-linking of tannins is possible. The
aerobic pathway probably involves the intermediacy of phenolic radicals,
produced from the reactions of phenols with triplet oxygen, undergoing
something akin to Wurtz coupling, possibly aided by transition metals
such as copper should they be present in the wine in catalytic quantities.

The anaerobic pathways involves the condensation of acetaldehyde, an
oxidation product of the alcohol in the wine, with two phenolic
molecules to produce a methylene-crosslinked biphenol. That's just
basic electrophilic aromatic substitution, a reaction that every student
in sophomore organic learns.

>
>> and a more palatable beverage for most people.
>
> It puzzles me, why do people drink young
> astringent wine? That's why I drink mostly white,
> they're less tannic.

Some people like a bit of bitterness in their wines. Others drink their
wines while eating red meat and the fats in the meat mask the tannins of
the wine. Some others have little choice: if you want to order a red
wine in a restaurant, you're limited to the (usually very young) red
wines present on their wine list. It's the rare restaurant that can
afford to cellar red wines as long as is needed to resolve their tannins.

Mark Lipton


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