I'm sure just about everyone is fed up
with the issue of cork
taint by now. I suspect magazine editors yawn wearily when they
get yet another proposal on the subject. It's been 'done' again and
again. But it's the issue that won't go away, and one that is in
danger of polarizing the different camps into a trench warfare
scenario, where each side just chants the same slogans repetitiously,
with the other side not listening. This is why I'm continuing to write
about it, hoping to forge a balanced position on the basis of good
data -- and not just anecdotal accounts, strongly held beliefs and
murky conflicting interests.
So, with this goal in mind, and as they currently stand, let me try
to crystallize the key issues in point form, trying to be as balanced
and factual as possible.
Cork taint is a problem. People are quite rightly cross about
the fact that the traditional closure ruins a significant
percentage of bottles of wineat source. While in some cases this is
due to the mechanical failure of the cork, in most instances it is
through the contamination of the wine with tiny (but still detectable)
quantities of trichloroanisole (TCA). Semi-quantitative estimates of
cork taint consistently come up with figures in the range of 2-7%,
although most of these studies don't involve chemical verification of
the presence of TCA in offending bottles, and no definitive analysis
has yet been carried out on a large enough sample. Even so, this is an
alarmingly high failure rate and one that many in the wine industry
consider to be intolerable.
Corks are the main culprit of TCA contamination. While there
are other sources of TCA contamination of wine, there is no good
reason to suspect that the majority of TCA contamination is NOT caused
by natural cork. The stochastic nature of the incidence of TCA
contamination, with one bottle being affected while others in the same
batch aren't, is supportive of this conclusion. So are experimental
data such as those from the ongoing Australian
Wine Research Institute (AWRI) trial. It's probably worth
questioning the independence (or judgement) of anyone who argues that
corks aren't the main cause of this problem. While there have been
well publicised incidences of TCA occurring endemically in wineries
these are rare, and when this has happened it has usually affected the
entire output of the winery, not just the odd bottle.
People differ in their sensitivity to TCA. The human olfaction
system needs to be taken into account in assessments of the rate of
cork taint. Studies have shown that people differ markedly in their
sensitivity to different odorants, with individual differences in
sensitivity as high as a factor of 10 000. There is every reason to
suppose that even the most highly skilled wine tasters will have
different biological sensitivities to TCA. This explains the often
reported incidents where two wine experts (MWs even) have disagreed
about whether a particular wine is corked or not. [Having said this,
even if one's individual sensitivity to TCA is low, a corked bottle
will presumably differ from a pristine one in other respects too.]
The Aus/NZ screwcap crusaders are running ahead of the data; the
pro-cork lobby is also misguided. Wine writers seem to be
polarizing into two camps on the issue of cork taint. On the one hand
we have the (mainly antipodean) contingent who have embarked on a
crusade against natural cork. They advocate -- with evangelical zeal
-- its complete replacement with screwcaps (known commonly and rather
irritatingly by the brand name 'Stelvin', or technically as ROTEs, for
'roll-on tamper-evident'). The other camp includes those in favour of
the cork. Members of this second camp vary in their mission: some deny
that there's a particular problem with cork, and that all the accounts
of cork taint are wild exaggerations. Others acknowledge the problem
with natural corks, but advocate sticking with them because they play
an important, active role in the ageing process of wine that we know
and like. I feel that both positions are ill-advised. Why? Well, the
screwcap crusaders are simply running ahead of the data. Although we
know that alternative closures work well in the short-term, there is a
lack of independent, statistically sound data showing that they will
work for long-term ageing of fine wines. Until we have these data, it
seems a foolish gamble for producers to shift from a closure that
causes failure in a few cases but works very well in others, to one
that could potentially ruin all their wine in 10 years’ time. Two
additional points here. The Australian contingent may well point to
Rieslings that have aged wonderfully over a decade ‘under Stelvin’
(with screwcaps), but this is not in controlled trials, and there’s
a world of difference between Aussie Riesling and classed growth
Bordeaux. We like the way that fine wines age under sound corks; we
need to be sure that these fine wines would age in a similar way under
alternative closures over time-spans of more than just a few years. On
the other hand, those who claim there is no problem with cork are
quite simply in denial. There’s very little reason to stick with
cork for wines intended for early consumption: this encompasses the
vast majority of all wines produced. And those who claim that cork
plays a significant role in the ageing of fine wine are merely
expressing an opinion in the evidence of data.
The only thing that will settle this issue is more scientific
evidence, not more lobbying or rhetoric. Personal opinions, no
matter how eminent or self-important the individual expressing them
is, are not going to settle this issue. Nor are crusades, no matter
how well intentioned. What we need are independent data from trials
that have been designed specifically to yield statistically
significant results. Non-scientifically literate wine writers may find
this hard to accept, but anecdotal evidence from tasting several
bottles of old wines sealed with synthetic corks or screwcaps -- while
of interest -- won't be much use in helping us reach an answer to this
important question.
Conflicts of interest must be disclosed. Because this is an
issue of economic importance, there's a lot of PR/marketing money
flying around. And some of it has found its way into wine writers'
pockets. However much these writers believe in the cause they are
promoting, once they take freebies or even cash retainers, they can no
longer hope to be considered an independent source of information on
this topic. They may still write sensible things on the topic, but
there's a worrying lack of honest disclosure by people who should know
better. If you write a piece on this topic and you've had hospitality,
flights or even payment from the cork industry or from screwcap
manufacturers, then to fail to disclose this is a breach of
journalistic ethics.
The environmental case for retaining corks is irrelevant here.
The environmental argument -- that we should stick to corks because of
ecological reasons -- is a smokescreen. It is completely separate to
the debate about whether better alternatives for sealing wine bottles
than cork exist.
Conclusion: a balanced view. For wines intended to be drunk
young, natural corks should be replaced with screwcaps or synthetics.
For wines intended for cellaring, let's stick with natural cork and
wait for the data to emerge showing whether the replacements will do
the trick. If they will, then I'll join the crusade for change. But
now it's premature.
See also: special section devoted
to the closure debate
Have anything to say on this issue? E-mal your responses to jamie@wineanorak.co.uk