Seems not…?
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I recall on a recent article by Jamie Goode, a couple of relevant points were made:
- the cork itself contains an amount of oxygen, that it will release post bottling
- oxygen transmission in a very good cork is negligible, and it’s very good corks on which we base our ‘ideal trajectory’ of a wine ageing.
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Well, this is a morasse of a topic and I’m hesitant to wade in, but a few things:
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Yes, oxygen transmission through a cork is not what ends up leading to large-scale oxygen ingress into the wine. Transfer of oxygen along the glass-cork oxygen interface is more important in old wines, as the cork loses its elasticity. Cork manufacturers know this, and DIAM states it explicitly. Their numbering system (DIAM 5, DIAM 30 etc.) is a guarantee of elasticity at 20 °C, not of oxygen transfer rate through the cork itself. Oxygen does pass through the cork directly, just very slowly.
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Regarding red wines intended for aging, it is hasty to say that ANY oxygen transfer into a bottle is harmful to the wine’s evolution. I’ve never heard anyone give a convincing explanation for why that would be. Oxygen does trigger a wide range of reactions in wine. Some of those are desirable. Some of those are undesirable. Exactly what the balance is will depend on the specific wine. Of course you don’t want tons of oxygen getting into your wine, but a little bit is not so bad.
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It is observably the case that oxygen modifies tannins. If you don’t do that in the winery, or don’t achieve sufficient softening by the time you go to bottle, having some oxygen get in from the cork pores, and then through/along the cork, will help to soften the wine. It’s true that we don’t have a complete understanding of how this works, but are we still arguing about whether or not it happens at all?
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Some aging reactions probably don’t involve oxygen. It’s extremely hard to tell which ones because there’s always a tiny bit of oxygen around. I would say we don’t have enough information about this to make declarations about whether or not oxygen is necessary for wine aging.
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The question is ‘complicated’ but not entirely. We know that oxygen helps increase polymeric pigment creation, especially with young wines. In this case, the actual quantitative level of tannnins is not altered - but by increasing the amount of tannins that bind to anthocyanins, we see a decrease in the affinity of these to bind to our salivary proteins.
We can increase these reactions with either temperature or, in most cases, oxygen.
Now over time, we know that tannins polymerize, or grow longer. Short chain tannins are bitter; as they get longer, they become less bitter and more astringent. As they get even longer, they become less astringent and, in some cases, become so long that they fall out of solution.
The question - do these polymerization reactions occur in the absence of oxygen? My guess is that they do - and their rate is dependent upon storage temperature.
Keep the discussion going . . .
Cheers
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and the answer to these unknowns may prove critical to understanding red wine evolution under screwcap, and whether the path to (and end state) maturity is different to that of a perfect cork sealed wine.
If we look back to the groundbreaking AWRI study and look at the pictures and the ‘data’, the ‘best’ corks showed similar data to screw caps. The big difference - the variability of natural corks was well over 1000 fold vs screw caps 
We know that screw caps allow permeability - and that it varies depending upon the liner used, as well as storage conditions.
We also know that Penfolds did bottle a very expensive wine in a completely closed glass bottle to explore this - anyone have info or data on this?
Cheers
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I’ve always argued from this viewpoint: convention wisdom tells us that bottles with the least ullage are most desirable, and likely to be most sound. If true, that strongly suggests that corks which allow the least ingress of air are best for aging, which would imply you don’t want or need oxygen for the optimum aging process.
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Agreed on all counts, Larry. I do suspect that the degree of continued tannin reactions in the bottle is oxygen-dependent, even if some reaction would happen in the absence of oxygen. Anecdotally, I once microcentrifuged samples of two very mature bottles of a well known Bordeaux chateau. One was much more oxidatively advanced than the other and spun out significantly more tannin into the pellet - with correspondingly lower residual color and tannin in the supernatant. Confounding variables abound, of course, but it’s a data point that stuck with me.
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What I think this implies is that slower is better when it comes to oxygen transfer – but likely only to a point. I assume there’s also likely a “happy zone” that occurs before zero oxygen transfer. If not, wine producers are ruining their wines by not closing them with a perfect seal, right? Not such a huge deal for the Josh cabernet that’s going to be opened a week after landing on the grocery store shelf, but a pretty big deal if your wines sell for thousands of dollars per bottle…
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My impression is that any increase in ullage is a result of cork failure to some degree, even if there is no visible leakage. Getting liquid out of the bottle is harder than getting oxygen in, so should theoretically be accompanied by relatively high oxygen ingress, likely beyond that which might contribute positively to aging. The question remains, then, whether or not 1 mg of oxygen getting into the wine each year is preferable to 0 or 0.5, for example.
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I would agree about the ‘conventional wisdom’ concept but there seem to be many exceptions to this - many on this board have commented about opening older bottles with noticeable ullage only to have the wine exceed expectations.
Cheers
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I wonder if any producer has done a long term trial where they actually sealed the bottle completely (meaning heat the glass to close on itself) then compared to cork years down the line. Probably not, and would be a tricky thing to do.
Note there is some oxygen already in the wine when it’s bottled, also some oxygen in the cork that diffuses into the headspace. SO2 in the wine helps mitigate the effect of the oxygen, and I’ve read it equilibrates after a month or so. After than, as Ben wrote, most of any oxygen that makes it into the wine comes along the interface between cork and bottle (for natural or diam), but can come through the body for synthetic corks.
-Al
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There was some research by Alexandre Pons that looked at MND in red wines over time in bottle. Low concentrations of MND tend to be related to freshness while high concentrations tend to give more dried fruit, advanced sensory impressions. They found that (a) less “ageworthy” wines produced more MND and more rapidly, and (b) over a 10 year study, all of the MND production is in the first five years of bottle aging, as oxygen from the headspace and then the cork pores reacts with the wine, after which a good stopper should limit additional MND production. This suggests that more ageworthy wines have a higher redox buffer capacity, i.e. they are less affected by the same amount of oxygen than less ageworthy wines. But when I asked him about his thoughts on MND he said he also suspected that the pool of MND precursors may be lower in more ageworthy wines, such that certain undesirable elements of the “aged” sensory profile may essentially max out in absolute concentration (though they may become more sensorially apparent over time as they are less masked by other desirable aromatics that fade with age). We know that this is true for some other things, such as 4-EP/4-EG production by Brettanomyces, which is ultimately limited by the pool of available hydroxycinnamic acids, so I don’t think it’s such a wacky idea. This idea may also help to explain why some wines that have seen a lot of oxygen during bottle aging (low ullage) can hold up surprisingly well.
It sounds from Larry’s earlier post that Penfolds did this? I don’t know about that study though, and would also be curious to know this results!
And @Jeremy_Holmes, @Brian_Loring , @Adam_Lee or any others with lots of experience with 20+ year old bottles under screw cap - ever notice much ullage?
Cheers
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Try no ullage at all - 20 years under glass stoppers. I’m only at 10 years under screw cap - again, no ullage whatsoever. And the older Kiwi wines I drink (mainly Felton Road) show zero ullage.
Peter Rosback
Sineann
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19 years under screw cap… using Stelvin with Saranex (breathable) liner… no ullage.
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Never.
Ditto for NZ wines; Felton Road started using screw caps in either 2003 or 2004 and zero ullage. Exact same experience with ALL other screw cap Kiwi wines.
The 2006 Kumeu River Hunting Hill Chardonnay is looking fantastic now at 18 years under screw cap.
Brodie