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Inquiring Winemaker TIM P A T TERSON C There's No Substitute for SO2 Highlights learly, the most important ingredients in winemak- ing are the grapes, without which we're left with fruit wine. The second most important is yeast, without which we just have grape juice. And a close third is sulfur dioxide, without which we might prefer set- tling for grape juice. Sulfur dioxide, says Zack Scott of Scott Labs, is "a miracle chemical, so perfectly suited to wine, and it does so many things at the same time." Grapes do one thing—ripen, at least most years; yeasts do two things—convert sugar to alcohol and (may- be) encourage aromatic compounds and precursors. SO2 does an amazing number of things: It kills unwanted and unpleasant microbes across several life-form kingdoms, combats the rav- ages of oxidation, binds up acetaldehydes (improving aroma), plays an important role in most winery sanitation regimens and YOUR SUCCESS IS OUR PRIORITY (Yet) • Sulfur dioxide plays a critical role in mainstream winemaking, but it also has a toxic downside. • Many winemakers are slowly reducing their use of SO2 ing more careful about timing and dosage. and be- • Several research and development projects already are seeking alternatives, but so far none have caught fire. dramatically improves the chances that a bottle of wine can sur- vive worldwide transportation and years of shelf life. "It will be VERY hard to replace," notes Michael Considine, a plant biol- ogy researcher at the University of Western Australia, "not least because it's so cheap." of the substitutes have gotten much traction. But sulfur dioxide has its downsides and its detractors, too. In excessive amounts it can be dangerous to wine drinkers, and in smaller amounts it can be downright irritating, causing head- aches, allergic reactions and so on. It can also be a workplace haz- ard if not handled carefully. Increasingly, the use of sulfur dioxide carries a kind of stigma in some quarters for not being "natural," despite the fact that fermenting yeasts always create at least a little of it in their brief careers. Perhaps the unkindest cut of all comes from California State University, Fresno, enologist Ken Fugelsang, who observes that although sulfur dioxide does many things, it doesn't do any of them particularly well: Its anti-microbial powers dissipate with high pH, and the anti-oxidant value varies wildly with wine composition. Because of the downside, an entire industry has sprung up seek- ing to develop alternative materials and technologies to replace sulfur dioxide. Yet because SO2 is so versatile and effective, none Just say no (more than necessary) There are, of course, an increasing number of winemakers who stay away from SO2 , or use it only in emergencies, and manage to make good wine year after year. (See "Wine: Natural, Natu- ral Enough, and Sort of Natural" in the December 2011 issue of Wines & Vines.) With healthy fruit, scrupulous cleanliness and perhaps some tolerance for elevated VA, sulfur-free winemaking can indeed be successful. There is little chance, however, that this 52 WINES & VINES AUGUST 2012