Issue link: http://winesandvines.uberflip.com/i/63937
WINEMAKING the world were working with over 75% everything else and less than 25% natural cork, it all seemed a little odd." The ulterior motive for DIAM was that if it could show, through a transparent, open study, that bottle variation experi- enced by the consumer was a significant problem, then producers might look to reduce that variation by eliminating sources of variation. One of those sources is natural cork, which, by virtue of being a natural product, is variable. But Gabbani also explained why it was important to do a scientifically reputable study: to put decent data in the public domain. "With DIAM I've always strived to only publish data that are as good a representation of the situation at the time. The debate can only move forward, and wine can only get better, with data that are beyond reproach. Too many people have been too ready to take sides (closure wise) based on propaganda, hearsay and sophistry." The panel (unpaid, motivated by the prospect of having access to some good data on this important topic) discussed the various aspects of the trial design and decided that the best way to begin the study was to conduct a preliminary investigation using 12-bottle cases of three different wines in 750ml glass bottles purchased at Bay Area wine retailers. The bottles were analyzed for variation in a number of ways to see which analyses were most likely to yield meaningful results in the main trial, and to decide the necessary sample size. Following this pilot, the main trial was conducted in 2010. What was analyzed, and how T ). SO2 is a good indicator of bottle variation, as the SO2 tests was ±3.2 mg/L, and the total SO2 aking place in the latter half of 2010, the main study involved 30 of the best-selling wines in the U.S. market: the top 10 sellers by volume in each of three price categories. Eighteen bottles of each were bought at retail stores in the San Francisco area, tested by technical and sensory analysis, and the results were analyzed by statistician Scott Shriver. The chemical analyses, carried out at G3's lab, looked for the presence of 2,4,6-trichloro- anisole (TCA, the chief culprit causing cork taint) above the reported threshold for detection of 0.5ng/liter, and the levels of total and free sulfur dioxide (SO2 was chosen because it levels will change with inconsistent bottling, inconsistent closure performance or exposure to heat—all of which can result in sensory changes in the wine. John Cunningham of G3 in Modesto, Calif., advised that the precision of the free SO2 precision was ±4.4 mg/L. The sensory work involved getting two of the judges to evaluate each bottle of wine on a range of criteria, scoring each on a 1-5 scale. These criteria were fruit, floral, earth, oxidation and TCA. Judges were randomly assigned bottles to evaluate, and each judge usually tasted three bottles of the assigned wine. J.G. Wines & Vines MAY 2012 57