Wednesday, March 02, 2005

TCA, corks, and other things...

Professor Bainbridge’s site has an open thread regarding cork and synthetic wine closures.
I’m also of the opinion that Mr. Laube is hypersensitive to TCA, and that I think to him the situation is much more dire than others think. (Am I being a hypocrite regarding Brett? Maybe…) But my experience is that certain cork producers may have large batches of defective cork from time to time, and pass that – sometimes knowingly- through to their customers.

On the one hand, a vintner wants to produce a wine free from any defects. But vintners also want to produce something that will sell, and some markets (high end reds, most high end markets in the EU and virtually all of Japan’s markets) are culturally biased toward traditional cork closures…anything less seems out of place and suffers in terms of sales & consumer acceptance. So it seems to me that we are stuck with the natural cork closure for some time to come, even IF a perfect closure is created.

The following link is from New Zealand, and discusses the touted benefits of super cleaning the cork particles to remove TCA before the corks are formed…,2106,3188835a7775,00.html

This is a high TCA taint rate in the NZ report. Defect rates are reported to run ~5% normally in New Zealand, and up to 25% on one vintage of Pinot! Ouch!
Previously I’d
blogged a note from a tasting in Australia where it was reported that 8% contamination by TCA was experienced (1-in-12 chance). Generally, 2~3% failure due to TCA is seen in the States.

None of these product failure rates are acceptable in any other industry, and shouldn’t be tolerated in the wine industry. I mean if somebody went to a new car dealer, and there was even a 1-in-20 chance that you’d walk out with a lemon…well, I think you get the picture…there’d be no purchase.
If you don’t get it, think of buying train tickets, with a 1-in-20 chance of the train running off the tracks…! Or airlines, boats, bungee-jumps, roller coasters, etc.
Really, who’d bother with buying it anymore?

Ideally there would be zero % contamination, though as realists I suppose we must concede that some failures will occur.


What is this deal with synthetic corks: why the lower free SO2 than with real cork?
Potential reasons include absorption of the SO2 into the polyethylene compound that the synthetic corks are made from. Perhaps it’s from oxygen trapped in the matrix of the synthetic cork during manufacture. The filling process itself doesn’t change with synthetics, and the same equipment can be used regardless of the type of cork closure employed, so it’s doubtful the difference occurs there.

The following links are to a Virginia Tech site where Prof. Bruce Zoecklein (a noted enologist & researcher) has some interesting notes on closures & oxygen in wine:
enologynotes#97 enologynotes#98

Of most importance I think is that there is still some debate – even among the researchers – of whether oxygen plays some role in the aging process of wine, and if it’s even desirable at some level or not.

Natural corks are reported to pass approx 0.0179 mg/l of oxygen into the wine, while screwcaps passed only 0.0005 mg/l of oxygen (or about a 35:1 ratio). If indeed oxygen is needed, then screwcapped wines should be nearly immortal from that perspective. I haven’t experienced any wines or closure trials that indicated any true immortality of the wines involved, and my estimate is that any difference in longevity would be around 2:1 at best in favor of screwcaps.

Can there be a plastic aroma in screwcapped wines? I haven’t encountered any as yet, but will continue to look for it in the future.


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