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WINEMAKING rely on enzymes and catalysts to accelerate a number of chemical reactions. "Feral fermentation starts slower (than a conventional fermentation)," La Follette admits, "but it can produce wine that is much more complex." Approximately 100 native yeast cells populate a milliliter of freshly crushed Pi- not Noir. Winemakers typically inoculate 10,000 times more commercially grown yeast cells per milliliter of grape juice for a conventional fermentation. The dense concentration of Saccharomyces cerevi- siae quickly overwhelms native yeast. "Natural fermentations can produce much more complex wines because the microbes driving fermentation are so diverse," says Seung K. Park, a visiting scientist at UC Davis and professor of food science and biotechnology at Kyung Hee University in South Korea. They can increase concentrations or change a variety of compounds to enhance the flavor, aroma, texture and mouthfeel of wine. A mixed culture of native yeast along with Saccharomyces cerevisiae can produce greater amounts of esters than a conventional fermentation. For Greg La Follette and other Pinot Noir producers, hops. Some species of native yeast, for ex- ample, uncouple the bound terpene from glucose making linalool, with its rose-like fragrance, 20 times more aromatic, but only when the yeast craves sugar. Under similar conditions near the end of fermentation, native yeast produce an enzyme called beta-glycoside, which helps drive the hydrolysis of important flavor compounds that enhance the varietal character of wine. In addition, a mixed culture of native yeast and Saccharomyces cerevisiae can produce significantly more fusel or higher alcohols than Saccharomyces cerevisiae alone. Fusel alcohols can add fruitiness to flavor and aroma. La Follette identifies aromas while punching down the cap on fermenting Pinot Noir. VintersSupply_acciai_Dec10.qxp 11/10/10 10:38 AM Page 1 higher concentrations of four esters (ethyl anthranilate, ethyl cinnamate, 2,3-dihydro cinnamate and methyl anthranilate) can enhance the variety's characteristic blackberry, black currant, cherry, plum, raspberry and strawberry flavors. Several species of native yeast can modify monoterpenoids, potent aroma compounds found in winegrapes and Ledcor_Jan11.qxp 12/7/10 2:30 PM Page 1 The ratio of fructose to glucose when 1 gram per liter of sugar remains at the end of a fermentation varies from a sponta- neous fermentation to a Saccharomyces fermentation. In a spontaneous fermenta- tion it can be 0.9 grams fructose or more to 0.1 grams glucose, according to La Fol- lette, while an inoculated Saccharomyces fermentation has a ratio closer to 1 to 1. Since fructose delivers twice the perceived viscosity and sweetness of glucose, a na- tive fermentation can enhance mouthfeel, La Follette says. 466 Devlin Road, Napa, CA 94558 Tel: (707)257-5231 Fax: (707)259-1257 www.ledcor.com/napa "Wherever we go, one constant remains: excellence. Time after time, we earn our reputation by delivering quality projects and customer service in an effort to continually exceed our clients' expectations. ' International in outlook. Innovative in approach. Diversified in capabilities. Dana Estates, Saint Helena, CA 20 Years Experience in Stainless Steel Manufacturing • Cross-flow Systems • Sheet Filters • Lenticular Filter Housings • Cartridge Filter Housings & Micro-filtration Plants • Lees Press Filters • Combination Filters • Pressure Leaf Filters • Tank Washers • Catwalks and Stairs VINTNERS SUPPLY COMPANY™ P.O. BOX 153 ST. HELENA, CA 94574-0153 TOLL FREE: 800-366-6809 • FAX: 707-584-7902 www.vintnerssupply.com 48 Wines & Vines JUne 2011