Wednesday, December 27, 2006

Fixing corked wine: An experiment...




It's like the ten plagues have been cast upon me in 2006 - I've encountered more corked bottles of wine in this one past year than in my entire prior half-century of life.

Now my friends may counter that this is probably because I've consumed more wine this past year than in the past 50. But this rumor just isn't so. Perhaps it is true that I've been drinking more vintage wines, thus more wines with a higher probability of having the TCA taint ("cork taint").

If you're fortunate enough not to have experienced a corked bottle of wine, you may not recognize the distinctive aroma and taste, variously described as, "wet dog in a damp wool jersey", or, "mushroom in Clorox stench". Whatever you call the experience, it seems to be one of growing frequency among wine consumers.

The phenomenon troubles me personally for a number of reasons. First, I've been blogging more wine tastings (in spiritofwine.blogspot.com) lately. Second, I've been buying more wines for long-term storage in my own cellar. Third, I'm doing more home winemaking and bottling (described in chezraywinery.blogspot.com). Fourth, I just bought a corker for these homemade wines. Fifth, I have secured hundreds of clean, empty 750 ml wine bottles in need of corks once they are filled with the homemade wine. And sixth, I just bought 1,000 brand new Portugese corks!

So my question for this entry (which I'll cross-post between spiritofwine and chezraywinery) is, having encountered a corked bottle of wine, Can you fix it? For extra credit, I'll ask, Can you quickly fix it?

To answer these questions, I'll perform an experiment based on two pieces of research that I recall. The first is that polyethylene can extract TCA from solution. The second is that activated carbon can extract TCA from solution. There are inventions and commercial products backing these notions. But there are also home-spun solutions. Let's try a couple.



First, I'll take the 1990 Tokaj that I recently reviewed, which showed a mild cork taint. I'll break the remaining Tokaj into four parcels of about 100ml each: 1) the original Tokaj; 2) Tokaj mixed with a "baggie", specifically an unused Glad Fold-Top sandwich bag; 3) Tokaj mixed with a 1-foot square piece cut from a light plastic Stop & Shop grocery bag; and 4) Tokaj passed through a used (but not expired) Brita water filter.



I'll test each parcel after a 2 minute treatment; then I'll Vac-u-Vin each sample and allow it to sit cold for a full hour and retest.

Here goes...



The first two-minute test included shaking and swirling each sample for alternate periods to ensure good contact with the plastics, and equivalent airing for the original and Brita-filtered samples. Results were as follows: 1) the slightly corked original sample was still slightly corked; 2) The Glad-bag sample was somewhat cleaner than the original, though I think I still would have identified something odd in the flavor; 3) The shopping bag sample was slightly cleaner than the original, but not quite as clean as the Glad-bag sample - there was only a marginal difference between 2) and 3) in corked aromas, and both were better than 1). 4) The Brita-filtered sample was an absolute transformation, delivering gobs of sweet fruit and nothing that even hinted of corked wine. Did it strip the wine of any of its original flavors? I can't say, but it definitely transformed what was a mixed experience into one that was wholly pleasurable.

So, in answer to the second question, Can you quickly fix a corked wine?... your best bet would seem to be a charcoal filter, Brita or otherwise.

Now, after an hour, I've retested. And, voila, we've got a change in the outcomes: 1) original was still just as corked as ever; 2) Glad-bag sample was extremely improved - bright, round, complex, just a hint of oak, or is that cork - hmm, not sure. But quite drinkable and thoroughly enjoyable; 3) Shopping bag is like 2), but without the hint of corkiness. Excellent. 4) Brita filter was pretty much unchanged from earlier, still round and sweet, but now it seemed flabby and flacid in comparison with samples 2) and 3). Maybe too much oomph had, in fact, been squeezed from the wine by the charcoal filter.

So, if you can spare an hour, here is the preferred method to rid corked bottles of the TCA taint: crumple a 1 foot piece of light plastic shopping bag (or Glad sandwich bag) into the bottle of bad wine, shake and let rest. (This might also work with plastic wrap rolls like Saran Wrap, but I have not tested that.) If after an hour, unacceptable corked aromas and tastes remain, go ahead and use a charcoal filter on the wine - plan to accept the loss of character in exchange for a drinkable wine.

Now that this is solved, I can go ahead and put those thousand corks to use without reservation, right?!

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March 26, 2007 update: "Bobinatti" from Cincinatti made the posting below on a wine forum that referenced the post above. It adds some real science to my simple experiment:

I am a chemist and I can see why this might work. The compound identified as being responsible for cork taint is 2,4,6 - trichloroanisole which has got three chlorines and a methoxy group attached to a six-membered ring. This is an extremely non-polar compound which means that it would likely be attracted to other non-polar materials. Enter polyethylene - also an extremely non-polar material. Having a sheet of this material gives you a huge surface area and giving it enough contact time allows for the adsorption of the 2,4,6 - TCA onto the plastic.

Now, you might lose a few flavor compounds too, but most flavor compounds are actually somewhat polar in nature, being esters, aldehydes, etc., so they would not tend to adsorb onto the polyethylene, at least not very quickly.

You might be able to find some other plastic that would work even better, but an hour is not too long to wait if you can recover a bottle of wine satisfactorily with polyethylene. Offhand, I would say that polystyrene would be very effective because it is aromatic (chemically speaking) as is the 2,4,6-TCA, so it would probably work even faster, but who knows what it might do to the rest of the flavors.

I concur with what someone else wrote about activated carbon. Activated carbon is a monster adsorbent and will suck all kinds of compounds out of the wine. There is no way the flavor profile will be unaffected by activated carbon treatment.

5 comments:

  1. Thanks for a fascinating experiment. I will definitely try the Glad bag technique the next time I encounter that pesky "wet cardboard" flavor.

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  2. Genius.. I'll remember this, and let you know how I fair.. (hopefully I won't encounter a cork'd bottle anytime soon)

    -Jake
    (http://www.grapethinking.com)

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  3. Very nice. just tried this on a corked bottle of 2002 Michel Shlaumberger Dry Creek Merlot. I would have given it about a 6 out of ten on a "corked" scale. I poured a glass of the tainted wine, fashioned a tea bag shape out of Glad clin wrap and swirled it in the glass for about a minute. It brought the cork scale to 1+-1. I could barely notice the taint. Thanksfor the tip!

    Also tried takeing a 2 foot sheet, rolling it up and shoving it in the bottle. Not very sexy,but it worked.

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  4. Glad to have confirmation the cling wrap worked too. Figured it should, but didn't think to include it in the original test.

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  5. An interesting solution to the “corked” problem—I’ll have to give it a try! I remain a proponent of the preemptive approach: the use of screw caps. It seems as though the US is slowly (although still with some hesitance) catching on to the trend.

    If you have any interest in the topic, check out this video that I filmed back in 2007:

    http://vimeo.com/9589462

    Thanks again for the interesting read.

    Paul Kalemkiarian
    President, Wine of the Month Club
    (http://www.wineofthemonthclub.com)

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