I recently hosted a Supertuscan tasting that was to be memorable given the lineup of wines, which included vintages of Guado al Tasso, Solaia, Sassicaia and Masseto. It surely was memorable, but for all the wrong reasons: The much-anticipated bottle of 2001 Masseto was, argh, corked. Wretched TCA! It almost drove me over the edge, well, almost. Corked Masseto!? 2001!? That hurts. So, being the scientist-minded person that I am, I decided to explore this further and see how I could fix this problem-aside from switching over to screwcaps, which I'm still resisting, being the traditionalist that I am.

TCA, short for 2,4,6-trichloroanisole, is a compound that produces a moldy, musty smell and is the result of a chemical reaction between phenolic compounds, present in both oak wood (Q. suber) and wines, and mold or chlorine, and which can be detected at extremely low concentrations, in the ng/L, or parts per trillion (ppt), range. The smell is what is referred to as "corked," which is unmistakably detectable in affected wines and which mutes aromas.

I had once read that TCA can be "removed" using butterfat or polyethylene (a thermoplastic). I never had the opportunity to try these out, but this Masseto experience gave me a serious incentive to experiment and confirm the remedies. Would they work?

The first thing I learned is that TCA is very difficult to create in a home laboratory. Yes, I did try to lace some perfectly good vino with chlorine (sodium hypochlorite) and a little mold that I scraped off some old barrel. Well, TCA did not happen, at least not that this nose could detect. In all likelihood, I did not have the right kind of mold. Luckily, I have a wine fault kit with a corked wine vial. The aromas and faults in these "nose-training" kits are fairly concentrated to make them easy to identify. So now I could easily infect wines.

Then, I learnt that TCA cannot be neutralized; it must be removed chemically. Mechanical means, such as filtration, at least not traditional filtration, will not work. Half-and-half milk (coffee cream) that contains between 10% and 18% butterfat is said to the trick, and as for polyethylene, good ole Saran Wrap should also do the trick given its chemical similarities to TCA. Oh! In case you are concerned about cream dissolving in the wine, it doesn't: The butterfat will grab the TCA and precipitate to the bottom.

I'm all set now for the experiment with this new-found knowledge.

So, I infected several samples of the same wine and proceeded to correct them with two kinds of coffee cream-one kind containing 10% butterfat and a second one with 15%-and another with Saran Wrap. And I had a control sample of wine to compare to the corrected wines.

The 15% cream worked better than the 10% one both in terms of precipitating quickly and cleanly, and in terms of removing TCA. The corrected sample was then "racked" through a coffee filter and evaluated against the control. The wine was clean and clear will no visible effect from the cream treatment. Where TCA concentration was relatively small, a rate of cream addition in the order of approximately 1500-2000 ppm did the job, with some impact on aromas. As the concentration of TCA was increased, the substantial increase of cream seemed to impact aromas noticeably more: Aromas all seemed to be muted to some extent.

This is all very interesting chemistry, but really not practical for solving a corked bottle of wine. The application is better suited for treating large batches of infected; however, if you have infected batches, you have bigger problems. This would point to a serious TCA presence in your home winery, and it is close to impossible to remove. The contamination would have spread from TCA-prone and infected surfaces, such as cartons and wood, which then easily propagates through the winery with a simple air draft.

The Saran Wrap solution also seemed to solve the problem but not to the extent I expected. That's probably because the TCA concentration was relatively high, but it did remove some TCA, and the longer the TCA-laced wines were in contact with the plastic wrap, the better the improvement. My tests used 15- and 30-minute contact times.

So there you have it. Just remember to take that box of Saran Wrap next time you go to a wine tasting party.

Daniel Pambianchi