Identifying and getting rid of TCA--that nasty little mold byproduct formerly known as "cork taint"--rates pretty low on the list of topics wineries like to talk about. But it needs to be high on any winery's list of things to be vigilant about.

For years, the wine industry thought that TCA (full name 2,4,6--Trichloroanisole) was exclusively associated with corks. The chlorine bleaching once used in some cork production promoted the growth of molds that would then spoil the bottles of wine stoppered with infected corks, producing a variety of unpleasant musty aromas and the suppression of fruit character. At the height of the cork panic a few years back, estimates of affected wines ranged anywhere from 3% to 10%, giving a major boost first to synthetic corks and later screwcaps as alternative closures.

Cork producers have made great strides in reducing taint levels to a fraction of their former incidence. More important, it turns out that corks are just one of many possible sources of contamination: Pretty much any combination of chlorine and cellulose can do the trick, as can some kinds of wood preservatives and flame retardants that may have been used on winery equipment and materials.

TCA can flourish in barrels, wood chips, cellar pallets, cardboard boxes, hoses and other equipment. In a worst case, it's not a single bottle that's affected but an entire tank, or an entire winery. The little bugger has several precursors and relatives, too--TBA, PCA, TeCA--enough to make up a whole family of unpleasant haloanisoles. And if your luck is running really bad, the problem won't be discovered by your lab staff, but by a prominent wine critic who has a sensitive nose and writes for a major magazine.

Here's a survey of what's out there for TCA testing and removal.

Testing for trouble

Even when there's no obvious evidence of TCA contamination, some form of periodic testing just to make sure seems clearly in a winery's financial interest; if there is a hint of a problem, it needs to be jumped on. The earlier a TCA issue is identified, the quicker and more cheaply it can be remedied. Simply relying on the cellar staff's sensory abilities and good judgment is probably not enough. TCA thresholds vary among people; low levels of TCA can easily be incorporated into the "house style" that everybody gets used to over time.

Two companies on the West Coast offer testing services: Vinquiry, with offices in these California locations: Napa, Windsor, Santa Maria and Paso Robles; and ETS Laboratories, with offices in St. Helena and Greenfield, Calif.; McMinnville, Ore.; and Walla Walla, Wash. Both offer roughly the same analytical services using the same basic technology, the tag team of gas chromatography and mass spectrometry (GC-MS). Because of the capital costs for the equipment--$60,000 and up--smaller wine labs are unlikely to offer TCA testing.

What gets tested is not the wine itself, but the volatiles extracted from the headspace in a closed container. For corks and wood products, the material first is soaked in either the winery's own wine or a model wine solution, and then the headspace is extracted and tested. Both companies also provide "TCA traps" that can sample a wine facility's ambient air, trapping any free-floating TCA in an absorbing medium like Bentonite, then sending the medium back to the lab.

Testing a single wine sample for TCA costs about $100, a full haloanisole panel a little more, with declining prices for multiple samples. If the labs, rather than the winery, do the soak for corks, there is a small extra charge; wood soaks cost slightly more. Air trap analysis is in the $150 range. Both Jerome Lewis of Vinquiry and Eric Hervé of ETS caution that the air trap method only provides a very general clue to a winery's possible contamination; a positive test simply means it's time to scour the site and find the sources and precursors for TCA.

Making it go away

There's no way to "neutralize" TCA once it gets into wine; it has to be removed. The various haloanisole compounds can't be removed with traditional filtration, or crossflow, or reverse osmosis. The only solution is to get it to stick to something, and then remove that something.

TCA and its posse of precursors will stick to certain polymers. As a parlor trick, swirling a little Saran Wrap in a glass of wine can clean up TCA; this approach also can be applied at the tank scale with larger sheets of the appropriate polymers. The more sophisticated methods involve running the affected wine past a magnet medium in a closed system, with the volume of medium and the number of recirculations depending on the level of TCA contamination. The TCA will adsorb onto the polymers forever. It will be out of the wine with no impact on wine flavor or aroma--other than getting rid of the TCA.

Winetech, located in the city of Napa, offers TCA removal at its facilities or at the client winery with mobile equipment operated by Winetech staff or rented and run by winery personnel. Technical manager Dario De Conti says the process makes use of a sealed canister containing polyethylene beads. The quantity of beads, the chief determinant of cost, depends on the level of TCA; the winery is responsible for getting the preliminary testing done. De Conli says the cost ranges from a dollar per gallon on up--a small portion of the difference between saleable and unsaleable wine.

Bryan Tudhope at VA Filtration, also in Napa, says VA uses a polymeric medium based on a material developed by Chevron in the 1970s for removing pesticide residues from wine. Like Winetech, VA Filtration can do the work at your place or theirs, with the price varying with the level of TCA. Tudhope also suggests a buck a gallon as a ballpark figure.

The most recent entry in the field is a variation on the theme from the Swiss company Filtrox, distributed in the western U.S. through Heyes Filters in Torrance, Calif. The medium in the Filtrox approach is an aluminosilicate commercialized from a material discovered by G3, the Gallo-related packaging arm, as part of research into alternate closures. The new wrinkle is that Filtrox embeds its trapping medium in more or less conventional filter sheets, under the Fibrafix TX-R brand, in standard sizes for plate or stacked modular canister filters. Clients simply buy the appropriate sheets--again, the number will depend on the TCA level--and put them to work in equipment they already own. The sheets aren't cheap--Greg Heyes says a 40cm x 40cm (about 16 inch x 16 inch) sheet is about $35--but, depending on the wine lot size, the price can be competitive.

Given the range of removal methods, some comparison shopping is advised before starting TCA treatment. Cleaning up your wine, of course, does not clean up the winery. Tainted corks and barrels are history; winery sanitation is a whole other project. (See "T'ain't Necessarily Corks," Wines & Vines June 2007.)

Butterfat grabs TCA     One seemingly old-fashioned but time-tested method to remove TCA is fining the affected wine with half and half. Unlike milk fining to remove tannin, in which the milk's casein is the agent of change, here the butterfat is what grabs the TCA. Any milk product will settle down to the bottom of a tank pretty quickly, and is followed by filtration. This may sound like a home remedy, but Bryan Tudhope of VA Filtration, which uses a very different technology, says that potential customers sometimes find the half and half approach is more cost effective for very large batches of 50,000 to 100,000 gallons of wine. T.P.