The Tasting Panel magazine

January / February 2018

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98  /  the tasting panel  /  january/february 2018 EDUCATION chance of it not having TCA, so we trace it," said Mattson. Oxygen and Wine With vast improvements in the battle of TCA eradication underway, the CQC is also spending a fair amount of time researching the variance in Oxygen Transmission Rates (OTR) among different types of closures. While oxida- tion is a wine fault that should gener- ally be avoided, very small amounts of oxygen are desired both for early consumption and aging. A natural cork inherently contains oxygen. As Weber pointed out in the seminar, a cork is 24mm in diameter, but when it goes into the bottle, it's 18mm. "Cork is fundamentally differ- ent from other closures in that it lets oxygen into the wine through diffu- sion," he explained. "Basically, when you squeeze a cork, you're going to release 2–3 milliliters of oxygen. Most of it is going to go into the wine." The CQC's study, which followed OTR in various quality levels of natural and synthetic corks over the course of 36 months, showed that a "dose" of oxygen delivered by the natural cork into the wine is released over a six-month period before leveling out. On the other hand, synthetic corks release oxygen through permeation, which appeared to continu- ally increase the dose without limit. For example, the greatest chal- lenge with Stelvin—an aluminum closure system that originated in the 1960s—appeared to be that it allows little to no oxygen into the bottle. This disrupts aging and may cause wines to be somewhat reductive early on. While wine aging is a complicated process with many unknowns at play, the study seemed to indicate that the initial release of oxygen from the cork at bot- tling is what allows the wine to develop over time. In regards to the transforma- tion of wine over a ten- or 20-year period, Weber noted, "It's obvious that they are continuing to develop, the theory being that the oxygen is helping that development. Which is why, to me, the screwcap guys are trying figure out ways to induce more oxygen." While we didn't have an opportunity for a side-by-side comparative tasting of a screwcap versus cork closure, Mattson discussed Jordan's own findings during the seminar. When screwcaps were beginning to take off in 2002, the winery bottled ten cases of its Chardonnay under Stelvin to compare with its traditional botting. Winemaker Rob Davis, who joined the winery in 1976, tasted the wines together once or twice a year; for the first five years he preferred the cork closure, as the wine seemed to develop better when young. However, at the ten-year mark, "the Stelvin got kind of interesting because it had the freshness we were losing on the natural cork," recalled Mattson. Yet, as one guest pointed out, if a consumer is purchasing a ten-year-old bottle of Chardonnay, aren't they looking for those aged characteristics? Consumer Perception Numerous polls have been con- ducted over the years that reflect consumer preference toward natural cork. Weber showcased a study from June 2017 that overwhelmingly showed its 1,549 respondents prefer natural cork, especially for wines meant to age (93%) and for high-quality wines (97%). Panelist Katie Madigan, who's worked at St. Francis Winery since 2002, can attest to this demand: The winery, which transitioned to synthetic corks in the late 1990s, switched back to natural cork due to protests from customers. "Our main complaint with the synthet- ics was oxidation," Madigan explained. J. Lohr Winery also struggled with an increase in cork taint in the early 2000s, and took steps to mitigate the issue by seeking a higher-quality product. A team traveled to Portugal to visit with producers and later received samples to help them decide which product they wanted to work with long-term. While the winery employs a number of J. Lohr Vineyards President and Director of Winemaking Jeff Meier. St. Francis Winery Winemaker Katie Madigan. At a Glance: Quick Facts You Should Know About Natural Cork There is no cork shortage; we have enough cork available today to sustain production for 100 years. Cork forests are increasing by 4 percent each year. Cork bark can be harvested every nine years, and the trees can live for up to 300 years. Corks are 100-percent biodegrad- able, renewable, and recyclable. Cork trees harness carbon dioxide and are a net positive in the battle against climate change. A wine is considered "corked" when TCA is present in 3–4ppt; that's the equivalent of eight drops of water in 800 Olympic-sized swimming pools. Current technology can detect TCA down to 0.5ppt—well below the human threshold. Though screwcaps and synthetic corks are recyclable in theory, infrastructure is not currently in place to adequately do so.

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