Controlling permeability can stop wine taint
discovered that controlling the permeability of the closure on a
bottle may be the best way to avoid TCA.
Two independent wine industry research studies, one in the US and the other in the UK, have concluded that controlled permeability in closures can improve the quality of wine.
The studies, commissioned by France-based wine and spirits closure producer Sabate, also revealed that wines sealed with prototype closures treated with a new technology that extracts TCA from cork, produced the best sensory ratings, and that different closures interact differently with various wine varietals.
TCA, or 2,4,6 trichloranisole, is caused when micro-organisms in cork combine with chemical contaminants used to kill bacteria in the closure production process. It gives the what is commonly known as 'corked' wine its trademark musty smell.
Both studies used panels of independent wine tasters. In the US, the panel assessed two wines, one red and one white, each sealed with prototype technical (cork-composite) closures free of any measurable traces of TCA, and with a screw cap. An existing Sabate product, the Altec, was used as well.
"After 60 years of experience producing and supplying mostly cork-based closures, we believed strongly that permeability was a significant yet highly discounted factor in contributing to the sensory qualities of most wines," said Sabate USA president Francois Sabate.
"One of our prime objectives in commissioning this research was to test this idea using technical closures we could be sure were free of TCA as well as an existing product already in wide commercial use."
The study, established to bring objective research to a critical aspect of wine production as well as to test a new, groundbreaking technology, will help Sabate in meeting marketplace demands for new and better products.
"Discussion of issues related to wine closures has been clouded by controversy and rhetoric based largely on emotion and individual agendas," said Sabate. "The debate has become irrational and counter productive, with some so-called experts calling for a screw cap on every wine and others making defensive appeals on behalf of cork that rely simply on romance and custom.
"The winemaker, in our view, has been caught in the middle. As a responsible company with a long tradition serving the industry, Sabate must operate on a foundation of research, reason, know-how and facts."
On a semi-industrial scale, Sabate manufactured three different cork-based closures, all with different levels of permeability. To eliminate interfering parameters, the prototype closures were treated under the TCA extraction process and included identical batches of cork flour, binding agent and microspheres.
The super-critical CO2 TCA extraction process, developed jointly with the French Atomic Energy Commission, relies on a technique similar to that used for decaffeinating coffee beans, according to Sabate.
The Stelvin screw cap was used as a control. The Altec closures, which are produced to limit releasable TCA to three ng/l or less, were picked at random from the Sabate factory in France by independent Master of Wines Peter McCombie.
"One interesting, albeit not highly significant, finding was that among the expert tasters there were a significant number of 'false positive' perceptions of TCA contamination in wines sampled, including wines sealed with the screw cap, " noted Sabate. "The panel, in fact, perceived TCA in wines closed with screw caps more often than wines sealed with the cork-based prototypes, all with no detectable levels of releasable TCA.
"But what that really spoke to us was the issue of permeability and its relationship to addressing 'reduction' in wine. The Altec, designed and manufactured to rigorously control TCA at a level uniformly lower than currently-accepted detection levels, did relatively well in these tests, though not as well as the other closures used in the research.
"Clearly, there is no perfect closure that suits every wine. Closure producers need to approach the marketplace with a toolbox of closure solutions. What works to address sensory differences in red wine, low permeability closures, for example, may not be optimal for certain white wines like Semillon that benefit from increased permeability."
Sabate is the closure division of the Sabate Diosos Group, a global leader in supplying value-added products to winemakers worldwide. The group is also the world's largest barrel supplier (Seguin Moreau and Radoux brands) and one of the world's largest closure suppliers serving the wine marketplace.
