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WIN e MAKING conventional breeding) are commer- cially available, but none of them are taking the high-alcohol sector by storm. The consensus among the re- searchers I contacted—Bisson, Julien- Ortiz, Charlotte Gourraud of Laffort and Karien O'Kennedy of Anchor in South Africa—was that a great deal has been learned about yeast metabolism, but that no major breakthrough was on the horizon. For the moment, the two best places to hold alcohol down are still in the vineyard or the reverse osmosis machine. Tim Patterson is the author of the newly re- leased "Home Winemaking for Dummies." He writes about wine and makes his own in Berke- ley, Calif. Years of experience as a journalist, combined with a contrarian streak, make him interested in getting to the bottom of wine sto- ries, casting a critical eye on conventional wis- dom in the process. Updating the 0.55 rule of thumb percentage of alcohol, may have been accurate in the bad old days of uncontrolled, open-vat fermentations without any temperature control, when a good deal of alcohol went volatile and disappeared. These days, with refrigeration, closed-tank fermentation for both A whites and many reds, and gentler pump overs and punch downs, not as much ethanol is vaporizing. Something more like 0.60 or 0.62 is a better multiplier, and occasionally a fermentation gets close to the theoretical maximum of 0.65. Cool-fermenting whites in closed tanks may retain slightly more alcohol than warm, ll this focus on ethanol yields has led to a re-calibration of the rule of thumb on sugar-to-ethanol math. The old industry standard, multiplying the starting Brix by 0.55 to get the final open-top Pinot fermentations, but there are enough other factors in the mix to make that less than a reliable generalization. Remember: This rule of thumb has climbed up not because the yeasts are making more alcohol, but because the winemak- ers are holding onto more of it after the yeast do their work. —T.P. 74 Wines & Vines JUne 2011