Are corks getting better? Judges at important wine competitions seem to agree that closures are showing less TCA than in the past, but they still note issues that seem to need addressing.
Christian Butzke, head of the enology department at Purdue University, said that only 1 percent of the 3,200 wines at the 2008 Indy International Wine Competition (2,135 commercial) showed signs of TCA, according to his self-described "super-TCA-sensitive olfactory bulb." He considered that acceptable.
Nevertheless, he noted that low levels of TCA, which can suppress wine fruit aromas, are difficult to determine in competitions and could affect the rankings of some wines.
Perhaps as interesting, Butzke's students have been counting the type of closures used, which can obviously affect the number of tainted bottles. He noted that less than half of the commercial wines in the 2008 competition were sealed with natural cork, closures, with another quarter of the wines closed with technical corks including agglomerated layers between solid cork disks or fully agglomerated cork particles in resin.
The move away from natural corks was even more pronounced in the Indy competition in 2009. Of the 2,504 commercial wines from 43 states and 10 countries, cork bark closures now seal less than two-thirds of the bottles (65 percent), with 35 percent of the total using solid bark cork plugs, 19 percent three-piece cork (solid disks at each end, generally with agglomerated cork in between) and 11 percent totally agglomerated.
Synthetics are 25 percent, and screw caps accounted for 7 percent.
They found 6 percent in screw caps and 17 percent in synthetic closures; 3 percent were bag-in-box, TetraPaks or aluminum cans.
The 2009 taint results aren't compiled yet. Butzke said students will analyze the approximately 30 or so rejects among the 3,000-plus bottles. He depends on his nose, which he considers pretty experienced, rather than lab tests, to determine whether the bottles do suffer from TCA contamination. "Unfortunately, that doesn't help detect subrecognition defects that simply mute aromas and flavors," he admitted.
He added, "We see few hard-core corked wines these days. I think it's less than 1 percent. That's not acceptable if it's a bottle of Margaux, but you have to open 100 bottles to find a bad one." He noted that the level rejected used to be 3 to 5 percent--a bad bottle in every other case. "That was annoying!"
Richard Carey of Vitus Research was a judge at both competitions, and his participation is most interesting because he had formerly made a study of cork taint at competitions in 2001.
Carey said that this year's Indy competition organizers considered that cork taint had gotten so low that they prohibited call-backs for back-up bottles, a policy he and many other judges objected to. He said that they said the level was below 1 percent, but disagrees. "I'm rather sensitive to TCA, and I was often the one who called out the problem." He said he thinks the level was more than 1 percent but less than 2 percent.
He added that screw caps will likely reduce TCA, but he found some wineries using screw caps seemed to be washing with chlorine in spite of a decade of warnings against its use in wineries. "Screw caps can't eliminate TCA if they continue to use chlorine," he said. He also detected reductive notes in some wines sealed with screw caps.
"I've come to the conclusion that winemakers should settle on one type of closure and make sure they optimize for it."
Carey feels that many contest organizers have discouraged examination of the number and type of tainted corks. "They don't make it easy to research the wines rejected," he said.
Interestingly, Carey finds that agglomerated corks without disks have the highest levels of taint. "It seems based on the specific manufacturers. I'd say you get what you pay for."
By comparison, according to an article in the June 6, 2001 Wine Business Insider, 88 bottles were considered corked among the 2,247 entries at the 2001 California State Fair's Commercial Wine Competition, a level of 3.9 percent.
The results: 59 of the tainted wines were sealed with natural cork of various manufactures (67 percent), 8 (9 percent) were sealed with "laminate" corks, one (0.01 percent) was a synthetic of unknown manufacture, and 21 (24 percent) were "cork and synthetic agglomerate" closures.
The overall results are somewhat similar to those of the 2001 San Diego National Wine Competition, which found an overall "taint rate" of 3.3 percent.
No analytical studies of the wines were conducted, however, and some of the wines may have suffered from other defects.
Riverside
Dan Berger could be considered almost the dean of wine writers with his long writing for both consumers and the trade, and he's also run the Riverside Wine Competition since 1982.
He said that 58 of the 1,806 wines at the latest Riverside competition May 1-3, 2009 were rejected, a level of 3 percent. He says those numbers should be taken with a grain of salt, though. "Fifty-eight wines were recalled, but there was no attempt at confirmation." He personally thinks that half a dozen weren't really corked. And half of those that were defective were manufactured corks--almost all on wines selling for less than $10.
Berger said, by comparison, in 1999, 8 percent were bad, though it dropped to 6 percent the next year.
Observers agree that the number of wines that are rejected for "cork taint" (TCA and related defects) has been dropping. This results from better processing and screening by natural cork closure producers as well as increased use of alternative closures, which probably reduce problems with TCA--though they may introduce other issues such as reduced wines. wbm
Cork Industry Data Shows TCA Levels Continuing to Decline
In the past few years, leading cork producers have spent considerable sums on preventative measures aimed at controlling and eliminating precursors to, and contamination from, 2,4,6-trichloroanisole or TCA, a compound associated with "cork taint."
Those efforts have been covered in detail in WBM, and there's a perception among winemakers that the incidence of TCA in corks has generally declined. The leaders vertically integrated their operations to control the raw material, improved their manufacturing processes and deployed advanced screening tools such as SPMI (Solid Phase Micro Extraction) machines to eliminate bad batches.
Taken together, these initiatives seem to have been effective though they haven't completely eliminated TCA from cork. (See "Insight & Opinion: Whatever Happened to Cork Taint?" WBM, September 2007, "Amorim to Introduce New Steam Cleaning Process for Natural Corks," WBM, September 2005 and "Signs of Success in Battle Against Cork Taint," WBM, June 2002).
Data collected by the California-based, Cork Quality Council, a group of producers, shows cork shipments continuing to see a reduction in TCA occurrence. During the past eight years the CQC says members have screened every natural cork shipment brought to their warehouses. Before they accept any lot into inventory, screening samples are sent to ETS Laboratories for GC/MS analysis of TCA.
For a typical lot of 100,000 corks, CQC guidelines require a minimum sample of 250 corks taken from a selection of at least five separate bales, which are placed in 50-cork wine soaks for 24 hours to extract releasable TCA. Resulting soaks are analyzed using a method that reports concentrations as low as 1 part per trillion. If one of the five soaks indicates TCA as high as 1.5 ppt, the entire lot is withheld from inventory.
CQC members conducted more 25,000 analyses last year. Their combined screening records over the past eight years show TCA levels are now 84 percent lower than results seen when records were first tabulated in 2001.
According to the CQC, the average releasable TCA level for natural cork shipments is currently calculated to be 0.66 ppt. The CQC screening protocol receives data with a minimum reporting limit of "<1.0 ppt." The group has agreed to treat these results as "0.5 ppt" for statistical purposes. Under this assumption, the statistical records cannot improve below 0.5 ppt. In the last reporting period, 93 percent of incoming cork shipments were tested at the <1.0ppt level. Another 5 percent had results between 1.0-2.0ppt. Approximately 3 percent of shipments were rejected by the CQC members prior to acceptance into inventory.
The CQC's members are Amorim Cork America, Cork Supply USA, Ganau America, Juvenal Direct, Lafitte Cork & Capsule, M.A. Silva Corks USA, Portocork America and Scott Laboratories. wbm
Editor's Note: It's been known for years that precursors to TCA can linger in the cellar and can form TCA when they come into contact with chlorine.
Find these previously written Wine Business Monthly articles online at www.winebusiness.com/wbm.
• "Taint Necessarily So," June 2002
• "Wine Defect Primer," February 2008
• "Hanzell Tells the Truth About TCA," December 2003
• "Insight & Opinion: Whatever Happened to Cork Taint?" September 2007
• "Amorim to Introduce New Steam Cleaning Process for Natural Corks,"September 2005
• "Signs of Success in Battle Against Cork Taint" June 2002
