Hi,
This is the article I promised Dick I'd write. In passing, I'll try to address some of the inconsistencies of experience between those who taste regularly ad professionally, claiming corked wines amount to 5 to 15% of the total, and those of us who have our collections of old bottles and find nothing like that proportion.
- Many of us are pretty insensitive to TCA pollution or rather fail to recognise it as such, and therefore don't recognise a wine IS corked when it is.
Having said that many of us don't recognise TCA, I think we have all experienced bottles where the wine simply doesn't "show" as well as we expected it to. I guess (pure speculation on my part, but I would submit from my own experience that it is probably valid) that in many cases, this is due to TCA in quantities below _our_ capacity to recognise it. Someone more sensitive might well. This has certainly happened once, in a tasting with Mark and Andrew in New Zealand. I also DID detect it on a heavily corked bottle that had Mark rearing away in disgust. Subsequently I detected it during a blind tasting (of corks vs other closures) in Bordeaux. This personal experience makes me suspect that I am not as totally insensitive as I'd thought I was. The corrolary of that, of course, is that I must have VERY rarely been exposed to TCA previously in [detectable-by-me] quantities.
- TCA pollution has grown in proportion in recent years. 30 to 40 years ago, it certainly existed, but was very rare.
This will explain to some extent why those of us who mainly drink fully mature long aged wines will have experienced many fewer cases of corked wines than professionals such as Michael Pronay, and others here. These wines haven't yet passed into our "drinking now" category.
Furthermore, I've seen winery owners claim that by being ultra fussy about where they buy their corks from, they have very few - if any - cases of corked wines. I take these claims with a pretty large pinch of salt, but I think it would be a mistake to reject such evidence out of hand. Why?
Corks are sold under a plethora of quality ranges. The prices vary widely and the supply of the very best is strictly limited. I have no reason to believe that corks made from fully mature trees and using great care in selection, do not have a lower degree of contamination, though this would be random and variable. I think this is almost the only explanation as to WHY experiences very, and WHY the levels of contamination have grown. Demand for cork has spiralled beyond the wildest expectation of the manufacturers, and there was no WAY it could have been predicted 40 or 50 years ago, when cork oaks would have had to have been planted to give adequate supplies of top quality corks now. So more - perhaps most - cork is produced nowadays from immature trees, and from less propitious areas.
If we look at the production of cork, one thing stands out above all others. Cork, being produced by trees, will vary, depending upon many factors. I have seen many suggestions as to how and why cork becomes polluted with TCA. The most convincing suggestion I've seen so far, is that it is a combination of the presence of chlorine (used to bleach and sterilise the cork) and bacterial infection. I have also seen it said that cork taken from younger trees is more prone to TCA pollution, though I don't know how speculative this assertion was.
I don't know whether any of this chlorine is present naturally - common salt consists of 45/68ths chlorine as a chloride, though normally this is pretty stable and I'd not expect free chlorine to be present from sea salt, I daresay that some hypothetical bacterial driven redox reaction might be able to give measurable quantities, but I doubt it is could be a serious contender for the supply.
Remembering that the major suppliers of cork are in Portugal and, I think, Slovenia (?) neither of which are renowned as highly developed and industrialised countries, I can well imagine that research into alternative methods of sterilising cork has been at best spotty.
Assuming that all cork manufacturers are still processing - faute de mieux - cork with chlorine, then although this is probably the prime cause, it doesn't seem to be felt by the manufacturers to practicable at the moment, despite the intense threat to the industry by Stelvin, to eliminate it.
So we are left with the other factors which seem a bit vague. "Bacterial infection", "younger trees". Time will solve the second hypothetical cause, though it seems to me to be doubtful that the wine industry is prepared to wait for the "younger trees" to become old enough, or for the cork industry to eliminate chlorine.
Where do we go from here?
Although the quantities are minute, compared with traditional (bottles) containers, flexible multiple ply plastic bags with taps work very well indeed for wines to be drunk within say 3 to 4 months of filling. Given the proportion of wines (bought in bottles) drunk within a week of purchase, I would suggest that this method will see a huge expansion. It deserves to. I have not detected taint of any kind in this type of container.
Another possibility would be to use cans. I have seen wine marketed in this way, but so far, it has been very much lower end wine.
Turning back to bottles, the alternatives to cork are three fold, I think. a) Crown caps (as used for aging champagne), b) synthetic cork shaped closures, which theoretically can be opened with corkscrews, c)Stelvin or other screwcap.
On the surface, and from the point of view of the wine maker, b) seems to have all the advantages, as they can use their existing bottling lines, and just change their supplier of "corks". However, all the information I've seen has agreed that these plastic closures lead to other off flavours in the wine. So for a serious wine maker, it is no solution to substitute one contaminating closure for another.
That leaves crown caps and Stelvin. Both are costly solutions. In both cases, the winemaker would have to change his bottling line to adopt them and this is a serious investment to envisage. That said, it is perfectly possible that, just as there are mobile cork based bottling lines which travel around the wineries, so there will be mobile bottling plants using crown caps or screw caps. It is also true that small producers can even hand seal using crown caps, I've done it myself for beer.
What is certain is that as more and more ordinary wine is bottled either exclusively under synthetic closures, or as an optional extra, so consumer acceptance will grow. It's FAR easier to unscrew Stelvin or even to rip off a crown cap, than to pull a cork - they stick, they crumble, they break up, they break in half, there's a whole litany of problems that accompany pulling a cork. In at least one supermarket in the UK, they won't buy ANY wine not under synthetic closures. Consumer law in the UK rightly gives the consumer the right to expect to buy a product of "merchantable quality", and gives her/him the right to seek remedy at the point of sale. A corked bottle ISN'T of merchantable quality, and even if only 10% of clients come back seeking recompense, this still represents far too great a proportion of returns to be acceptable, not when the solution exists.
I think that in many countries, we're approaching a cusp where it will be as unthinkable for the consumers in that country that a winery should NOT offer wines under screw cap, as it is at present for corks. I hope so, because While not ALL TCA pollution is cork borne, best estimates suggest that 90% of it is. Elimination of THAT part would enable winery managers and consumers to put their finger on exactly how serious winery and barrel borne infection really is.
When consumer acceptance is virtually universal (except in France, of course) for "ordinary" wines, then two possibilities arise. It could well be that the reduction of pressure for cork closures world wide will finally allow the manufacturers to reduce the proportion of TCA contaminated corks to a sufficiently low level for them to be acceptable again. They could then find a "niche" market at the top end, for people who still want to age wines for >40 years and believe that cork is the "way to go". I find a parallel in HiFi, where valve based amps and direct cut vinyl have kept a market, while the great mass of the offer has moved on. Given that corks can be inserted using small scale machinery, this would be perfectly possible. I worked at this in a holiday job some 40 years ago, so I know that it is perfectly possible for one man to bottle a barrel in about an hour, allowing abt 20 seconds a bottle.
Another possibility is that winemakers, who have installed Stelvin or other alternative screw cap or crown cap bottling lines, for the lower end wines, designed to be drunk young, simply abandon corks, even at the top end. I'll not weep tears for the cork manufacturers, who didn't take the problem of TCA seriously enough for >20 years. What THEY'll have to do is to find alternative uses for the raw material. It is still excellent for many things where there is no food contact.