04microbesandfermentationbw2

04microbesandfermentationbw2 - Wine Microorganisms and...

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Wine Microorganisms and Fermentation 1/17/2008 1 1 Wine Microorganisms and Fermentation Introduction to Winemaking, VEN 3 Andrew L. Waterhouse Department of Viticulture & Enology University of California, Davis 2 Some Terms Seeds and skin after pressing Pomace % sugar, 20-28 ripe grapes Brix Crushed grapes and juice Must Ethyl alcohol, EtOH, ethanol Alcohol Hydrometer L, Refractometer R 3 Sulfur in Wine Yellow elemental sulfur S 0 or S 8 • Powder for treating mildew/fungus-mined Sulfites, SO 2 , HSO 3 - (label on wine bottle) • Preservative used in fruit, wine processing • Antioxidant, kills many microbes, removes oxidized aroma Sulfides, H 2 S • “Reduced” Aroma, rotten eggs, cooked vegetables • Yeast can make H 2 S from S 0 4 F e r m n t a i o P c s g A d YEAST YEAST WINE WINE GRAPES GRAPES GRAPES Fermentation 5 Yeast, The Other Organism A fungus A lower plant 6 Wild Yeast Live on the surface of the grape berry •BUT they are not ideal for wine production Not to be confused with “natural” wine yeast
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Wine Microorganisms and Fermentation 1/17/2008 2 7 Strong flavors Alcohol intolerant • Residual sugar means the wine is microbiologically instability Unpredictable SO 2 sensitive Characteristics Of Wild Yeast 8 Used for making Wine Beer Bread Distilled beverages The Wine Yeast Saccharomyces cerevisiae The Wine Yeast Saccharomyces cerevisiae 9 The Wine Yeast Saccharomyces cerevisiae Also found on the surface of grape berries •BUT in much lower numbers than wild yeast 10 The Wine Yeast Saccharomyces cerevisiae Becomes established on winery equipment Can build up in vineyards where pomace is deposited 11 Out competes wild yeast in mixed fermentation Must is usually inoculated with a commercial strain of wine yeast The Wine Yeast Saccharomyces cerevisiae 12
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04microbesandfermentationbw2 - Wine Microorganisms and...

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