cork taint and related issues: Nick Alabaster

When is cork-taint not cork-taint?

You suspect there's something wrong with the glass in front of you, but you aren't quite sure. In this detailed review, Nick Alabaster discusses some of the problems quality issues facing wine that often get confused for cork taint.

With such a title you’d be excused for thinking I’m going to start off with a joke. However, neither do I have a joke, nor do I think cork-taint is a laughing matter. Too much is at stake: on the one hand millions of bottles are being damaged yearly by faulty closures, and on the other, a multi-billion pound industry is trying to convince everyone that natural cork is still the only choice for sealing wine bottles.

Lots has been written on cork taint. However, the purpose of this piece is to separate cork taint from other quality issues affecting wine, where possible, and identify where this just isn’t possible.

The umbrella declaration of ‘cork-taint’ has too long been assigned to any bottle that performs below expectations. This has not helped. People still think of cork particles floating in their wine as corked; oxidised wine as corked; heat or light spoilt bottles as corked. This has blurred the real issue, and there is a real issue: that is the genuine taint that is derived through cork, and spoils a wine irredeemably. There are a number of compounds associated with cork-taint: TCA (the primary taint – 2,4,6-trichloroanisole), TceA, TBA, PCA, DCA and others (and I’m not just making them up!). Also, other chemicals present in wine can also be associated with corks, as I shall mention later.

But is the cork the sole mechanism by which the spoilage compounds can enter a wine? No; there are the winemaking barrels and other oak-based wine products too and these also harbour an environment in which the same pungent compounds that taint our wine could form.

And can you be absolutely sure that when you think you smell taint, it is TCA? Again, no; not without knowing more about the wine you’re drinking, and without discounting other potential issues first.

At the mass wine sales end of the market, the cork-taint issue has been conveniently hidden from the consumer. But why should the mass-market consumer care anyway? If a wine doesn’t perform, or is not liked for any reason, the supermarkets and high-street merchants take back or exchange wine for any reason you care to give. And how often does the retailer actually hear of people correctly using cork-taint as the issue? Well, on the supermarket side of things, my experience tells me it’s not often: most consumers simply aren’t aware of the problem. Even if they think they are, as often as not they’ll confuse it with something else sub-standard about a wine. However, the retailers do care: they care that products are either being returned or not repurchased. Hence we are seeing a big drive in the screw-capping of wines at the lower end, with the supermarkets doing their best to deliver fresh, taint free products to the mass market. At this end of the scale, I simply don’t see any reason in a quality sense, why all ready-to-drink wines aren’t packaged this way. Why take the risk of taint when you use natural cork for such a short period? But image is also key to a product’s success, and unfortunately natural cork still has an image that implies quality. If only everyone knew the true price they are paying for that image…

On the other end of the scale, avid wine collectors and drinkers are painfully aware that a Ł1000 prized bottle is in no way immune to the damaging effect of cork-taint. Added to that, if the wine isn’t opened until years or even decades after it was bought, how can anyone expect any fair exchange of goods should it be tainted? And it is for the more interested consumer that I think a discussion about the many guises of cork-taint and other possible ‘taints’ is worthwhile.

Cork-taint is not only extremely variable between cases, but so is our sensitivity to it. As important as our innate ability to detect certain compounds – which can vary enormously - is that recognition of compounds in wines can be drastically improved with experience. I believe I’m fairly well tuned into the TCA aroma and its effect on wine, however, frustrating as it is, there are still cases in which I just can’t be sure.

Here is a list of the aromas and effects of cork-taint, as generally described:

wet-cardboard
musty
mouldy
mushroomy
medicinal
earthy
spicy
lack of aroma
lack of fruit
elevated acid

Effects of oak and cork-taint
The impact of oak and cork-taint is closer than some people give it credit for, yet why should they not be – they are both from the same source! There is a particular chemical which would be considered positive in oak, but not so in cork. In one case guaiacol impacts a smokiness which is precisely what some oak treatment is designed to do. However, if it randomly comes out through the cork, then this is more likely to be frowned upon. It’s entirely likely that if this chemical does come about through cork, then other less appealing flavours will also be introduced. So, do I think cork taint and the effects of oak can sometimes be confused? Yes: not often, but I do. It may be that the source of my confusion is actually the same source, TCA or related compound, but I’ve found a certain type of barrel toasting characteristic to prick my senses to the potential presence of cork taint. It’s happened on a number of occasions, but as I’ve found other people not to be convinced by a call of taint, it makes me think that it isn’t TCA, but perhaps some other shared or similar chemical. However, sometimes the only true test in this case is to refer to another bottle, and see if variation between them clearly puts in the likely cork-taint bracket. Of course, if TCA is recognised in numerous bottles, then the source is quite likely to be the barrel, and the cork can be forgiven. (But in this case, not the winemaker.)

Effects of yeast and cork-taint
No this is were I hold up my hand and say, you’ve got me confused here. A number of times when I detect the yeasty, leesy or similar aromas in a wine and I start to wonder about possible cork taint. Sometimes that thought has been well warranted: cases at tastings where I’ve asked for another bottle and been given a cleaner wine, but other times another bottle comes back the same. If only these incidences were getting rarer:unfortunately not. Maybe this is where an innate ability is letting me down, or maybe that mushroomy, yeasty/mouldy element is just so close to being one of the same? The wines I find particularly troublesome are Burgundies and Champagnes, where the yeasty, leesy characteristics are now highly sought after, but there are other white wines too. In one recent case, I thought an element of taint was there (it seemed to get worse with time), but then gone: not even a yeast/lees character left – what caused that I wonder? (TCA is not usually volatile enough to dissipate with air, although we do assimilate it very quickly with the net result we think it’s gone, when it hasn’t really).

Effects of unclean glasses and cork-taint
Although it’s easy to discern the effect of detergent or mould in the glass by comparing the wine in a perfectly clean vessel, I wonder how many bottles have been returned without considering the glasses to be the cause of the off taint? I know I had an issue with a water filter that must have developed mould within the carbon element. However, it only came to light after several bottles seemed affected, and I realised the wine was releasing the dried aroma which clung to the glass. (It could be detected by breathing into the glass also – a good method for releasing potential taint material.)

Brett and cork-taint
Brettanomyces is a yeast taint which can impact a wine widely, from a gentle earthy/spicy edge, through to medicinal, leathery and animal to farmyard and stables. Now this is a relatively recent comparison for me, yet I know several people who swear they’ve always had a problem separating the two at some levels. But recently I’ve come to find that the spicy/earthy side to brett is indeed something which cork could have imparted, or vice versa. When testing for brett, one of the chemical fingerprints is 4-ethyguaiacol. Am I clutching at straws here, or is that in no small way related to the chemical found in oak and cork? One thing I’ve found is that some wines which have been called corked have not got any worse, over many hours or even days. And that, based on my experience with TCA, doesn’t add up: it just about always gets worse with air. Now I suspect that it could be an element of brett which gives a more consistent profile. I recall a dinner many years’ ago where some around the table said TCA, but I said I couldn’t get to the TCA for the brett. Now, either the wine was unlucky and had both (definitely a possibility, it was a Burgundy after all!), or we were in fact smelling the same thing. I’m not sure how much bearing it has, but both TCA and brett have the effect of subduing fruit, and so once again given rise to the possibility of confusion. Although I personally find the medicinal smell of phenol compounds quite distinct from TCA, there are others that put medicinal in the possible TCA bracket, and so here is another potential source of confusion.

Conclusions
Overall, the last thing I want to do is downplay the cork issue; in fact, quite the opposite: I think the cork issue is wider than just about taint, but the whole issue of irregular seal and bottle variation. However, it is equally unhelpful to misdiagnose TCA and be misled into thinking that cork-taint is the only issue affecting wine quality today, so I’ve laid out my thoughts on what you might like to consider just before you next think about declaring a wine ‘corked’.