In article , Mark Lipton wrote:
Bruce Sinclair wrote:

To paraphrase my earlier post, all (or most) reactions that occur in bottles
are considered 'bad'. That's why many/most winemakers are now putting the
vast bulk of their production into screw top bottles. The 'bad' reactions
are reduced, and the wine tastes like they want it to. IME, this is a very
good thing.

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 and a more palatable beverage for most people. The deleterious
reactions mostly involve the unwanted ingress of oxygen, though an
ongoing debate concerns whether some amount of oxygen ingress is a
positive for the wine. To the extent that they control oxygen ingress
more effectively, screwcaps are a positive development in the sealing of
wine bottles.

Mark Lipton
(a wine loving Ph. D. chemist)



Yep ... but ... can the wine maker not allow the aging process in their
large containers to continue past what they would have before screw tops, so
that the wine they bottle is the wine they want you to have ?

My understanding is that they now do age past what they would have, and
because they know there will be very limited changes once bottled, can leave
it till they think it's ready.

I do note however, that the wine they still bottle under corks is
predominantly reds.

z (Bruce Sinclair) writes:

In article , Mark Lipton wrote:
Bruce Sinclair wrote:

To paraphrase my earlier post, all (or most) reactions that occur in bottles
are considered 'bad'. That's why many/most winemakers are now putting the
vast bulk of their production into screw top bottles. The 'bad' reactions
are reduced, and the wine tastes like they want it to. IME, this is a very
good thing.

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 and a more palatable beverage for most people. The deleterious
reactions mostly involve the unwanted ingress of oxygen, though an
ongoing debate concerns whether some amount of oxygen ingress is a
positive for the wine. To the extent that they control oxygen ingress
more effectively, screwcaps are a positive development in the sealing of
wine bottles.

Mark Lipton
(a wine loving Ph. D. chemist)



Yep ... but ... can the wine maker not allow the aging process in their
large containers to continue past what they would have before screw tops, so
that the wine they bottle is the wine they want you to have ?

My understanding is that they now do age past what they would have, and
because they know there will be very limited changes once bottled, can leave
it till they think it's ready.

I do note however, that the wine they still bottle under corks is
predominantly reds.

The first question you ask assumes that the aging that takes place
before bottling has the same effect as the aging that takes place
after bottling.

It also assumes that (if the winery thinks that a certain wine peaks
after 7 years) they can afford to hold onto it for 7 years, aging it
just right, and then putting it into bottles at the perfect moment,
stopping aging at that moment. All fairly questionable.

As to your second paragraph, most wine that is sold in the world is
sold shortly after the retail establishment purchases it, and is drunk
the night the consumer purchases it. So if it gets any aging at all,
it is typically aged by the winemaker. But for that small percentage
of wine that really does get aged before drinking, I didn't know that
winemakers are aging it more on premises than they used to. I'm
interested in the source of that statement.

It does seem true that a screw cap changes what happens (mostly for
the better in my opinion), but it doesn't prevent aging in the
bottle.

On 12/04/2012 00:26, Bruce Sinclair wrote:

Yep ... but ... can the wine maker not allow the aging process in their
large containers to continue past what they would have before screw tops, so
that the wine they bottle is the wine they want you to have ?

My understanding is that they now do age past what they would have, and
because they know there will be very limited changes once bottled, can leave
it till they think it's ready.

I don't think winemakers release screwcapped bottles later than corked
bottles. When bottles are released often has more to do with cash-flow
than anything else. Some producers hold some bottles back and then sell
them for more money, but that is in effect an investment for them, and
more usually they prefer to get the income ASAP to run the business.

Poor corks may allow more oxygen into the bottle than screwcaps, and
corks do have other effects like sometimes adding bad flavours, or
removing flavours. But screwcaps still do allow in some oxygen, and
there are many other changes that take place in-bottle in the absence of
oxygen.

Also bear in mind also that different people want different things.
Some like young wines, some very old.

I do note however, that the wine they still bottle under corks is
predominantly reds.

That is true, but a lot of reds are put under screwcap too, particularly
in Australia and New Zealand.

--
www.winenous.co.uk

On Apr 11, Mark Lipton wrote:
To paraphrase my earlier post, all (or most) reactions
that occur in bottles are considered 'bad'. That's why
many/most winemakers are now putting the
vast bulk of their production into screw top bottles. The
'bad' reactionsare reduced, and the wine tastes like they want it to.

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?

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.

--
Rich

On 12/04/2012 19:56, RichD wrote:
On Apr 11, Mark 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?

Yes, anaerobic. It is also called reductive (as opposed to the
oxidative ageing that takes place in the presence of oxygen). See
http://www.wineanorak.com/tannins.htm
Especially the paragraph about 2/3 down.

--
www.winenous.co.uk

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


--
alt.food.wine FAQ: http://winefaq.cwdjr.net