You can read some of the research, including that behind the pictures posted. As others have said, when you allow air in, you produce oxidation. That may or may not be important in aging. But if we imagine that some amount of air through the cork is required, please let us know exactly how much air is required to age a wine 20 years to perfection. Then we can manufacture a closure to specifications that allow such ingress, rather than rely on the randomness of cork.
Well we posted at the same time John. I agree with what you said, since you said it first!
We sulfur wines to prevent oxidation. Because we don’t know how bad our corks will be, we sulfur for the worst case scenario. “Aging” is a whole collection of different chemical changes that really don’t require new fresh oxygen once a wine is bottled.
The Aussies have been doing very long term testing of various types of closure. As Hunter Valley Semillon can age gracefully for decades and is very light it’s the perfect wine for them to see how different closures affect ageing and taste as well as oxidization.
So the picture is Stelvin on one end and I think as mentioned those cheap plastic corks on the other. Along with the resin/ground cork closures, glass, various grades of cork etc. You can see that there is one cork closure (second from the left) which is pretty much identical to the stelvin. Perfect cork is probably just as good but who knows if you’ve got a perfect cork?
Wax may be marginally gas permeable but I have to think it certainly doesn’t make more gas transfer! It might not stop gas transfer from a lesser cork but I’d have to think it at least moderately lessens it.
I already know a bit about the research in question. Consequently, I am well aware that screwcaps are way more consistent than corks when it comes to oxygen ingress, and can be manufactured to allow as little oxygen ingress as the tightest of cork but also to allow more than that if desirable.
You define aging as those processes that don’t require any additional oxygen once a wine is bottled. And if you define aging that way, then it is of course true by definition that it does not require any additional oxygen. What is not yet clear, to my knowledge, is the extent to which aging defined in a way that does not make the answer trivial, e.g., as a desirable process of in-bottle maturation, benefits from some minimal additional supply of oxygen or not.
Malcolm J. Reeves (pp. 231-232 in the source specified below) summarizes the situation as follows:
"The amount of O2 required for optimal development varies from wine to wine. Some wines become reductive with insufficient O2 (Vidal and Aagaard, 2008). The ingress of small amounts of O2 can result in the production of quinones from phenolics, leading to the loss of odorous sulfur compounds; SO2 is also intimately involved in this situation.
Wines such as Syrah are prone to the development of sulfur-like odors (SLOs) that can be formed from precursors in the wine such as S-methyl methionine (Vidal and Aagaard, 2008) either by hydrolysis or under anaerobic conditions during fermentation, barrel aging, and bottle aging (Limmer, 2006a). Some SLOs can make a positive contribution to wine quality but at high levels are considered a fault."
Source: “Packaging and the Shelf Life of Wine” in Gordon L Robertson, ed., Food Packaging and Shelf Life: A Practical Guide, CRC Press 2009
Yes, it’s certainly open to scientific debate. I am personally inclined to like screwcaps and dislike corks, which means I hope the guys Goode cites are right. But what I was trying to say is that I don’t know that the scientific debate in question has ended and ended with the conclusion that minimal air ingress is universally desirable for the ageing of all wines or that all wines can be made so as to include, prior to bottling, all the oxygen required for the desirable kind of maturation. See also my reply to Greg above.
Thanks for explaining pic.
But the bottles are not the exact same, followed over time ?
Bottle no. 6 from left eg. has low fill at 63m. -and high fill at 125m.
And others appear lighter at 125m. than at 63m. (Could be different light setting, -but that would also be a grave bias, when comparing aging colors.)
But the screwcap is the winner, I can see that.
-If wax caps really were good and added some noteworthy sealing-function, then all the top prod. would use them, I guess ?
(But it can look romantic, and nostalgic, if not cracked along the way.)
I’ve recently tried waxing the tops of coravined bottles after pouring, to prevent oxygen from getting thoguht the hole caused by the needle. I was hoping this would allow me to use the device on my older wines (the method was actually suggested to me by Greg Lambrecht, the inventor of the device), however it had no effect whatsoever. The bottles with old corks still turned within a month. So basically, the device is still useless for older wines due to the natural loss of elasticity in the fabric of the cork.
I recently had a 1978 Chanson Pommard at a friend’s house. He showed me the bottle before cutting the capsule, and there was no cork in the neck! It was floating around in the wine, and had apparently dropped in more than half a year before when he was rorganising his cellar. He had put it aside and forgotten about it, until coming on it by chance recently. As he knows I’m partial to the odd wine experiment he brought it up from the cellar when I came over. The odd thing was that the seal was still perfect - turning the bottle upside down did not cause it to leak in the slightest. We cut the capsule and left it for half an hour to allow it to acclimatise. To cut a long story short, the wine as fantastic and showed no signs of oxidisation!
Going from the above (admittedly limited as it is), I suspect that old-fashioned lead capsules may be a lot more effective than wax, when it comes to creating an air-tight seal.
Soren, the bottles were arranged in order of color at each timeframe, not the original photo’s sequence. It makes sense that a bottle with a lower fill would, over time, move farther right as it ages and darkens.
Ok, thanks Chuck.
I understand now, that some more detailed descriptions are needed, to fully understand the photos, and the full experiment.
I read some time ago, that Ch. Margaux, and some other names, were conducting some sealing tests too.
Anyone heard of these results, or is it yet to early to conclude anything ?
Someone posted a story a year or two back about a wine that was missing its cork – probably a bottling line glitch. That bottle, too, was fine, based evidently just on the capsule. Go figure!
Beat me to it. And once the initial engineering is done, that cost becomes a negligible part of volume production.
My brother used to work on permeability of various materials - plastic wrap for strawberries, contact lenses and replacement corneas, etc. If people know what the optimum air exchange is, they can build it. And they’re doing the research in CA as well. Our own Larry Shaffer puts all of his wine in screwcaps. Randall Graham poured a wine for me a few weeks ago that he’d aged under screwcap for years. Earthy, meaty, gamey, it tasted exactly like a wonderful aged Syrah. Which it was.
Just acquired the second edition of the book by Jamie Goode that John cited (now entitled Wine Science instead of The Science of Wine). The section on closures has been revised quite a bit compared to the first and strikes a much more cautious tone with regard to the desirability of a perfectly impermeable seal (or one as tight as the tightest screwcaps) for wines produced with some bottle-aging in mind. Suffice it to quote the concluding paragraph:
“In conclusion, there now exist several alternative ways of sealing a bottle of wine. Oxygen transmission by these closures seems to be very important in determining the way the wine develops in bottle, but there is still few solid data on what is taking place here, and what sort of levels of oxygen transmission are appropriate for different wine styles. This makes it tricky for winemakers to choose the right closure, from a purely scientific point of view.”
None of this is of course an argument against screwcaps since they can be designed with different levels of permeability while at the same time keeping a particular permeability with far greater consistency than corks. The problem is simply to determine what the best level of closure permeability for a certain wine actually is.
Baller move would be to put on a screw cab then wax to fake people out. “Hey look at my fancy bottle - oh wait it’s a screw cap!” Would probably ruin a lot of corkscrews as well. For the record I am a big support of screw caps on all bottles.
to the original poster … Any material substrate that impedes the trans Ox rate changes something … is it better ? I would bet this is bottle specific or vintage specific… you can not make absolute conclusions on this wax, just that something changes and sometimes I bet the wine is better and sometimes it’s worse …