Yeast Fermentations Beverage Yeast Method of Preparation Function of Yeast Beer and Wine Beer,lager Saccharomyces Germinated barley releases starches Converts sugar into alcohol cerevisae and amylase enzymes(malting). and carbon dioxide;>6% (bottom yeast) Enzymes in malt hydrolyze starch to alcohol.Yeast grows on fermentable sugars (mashing).Liquid bottom of fermenting vessel. (wort)sterilized.Hops added for flavor. Yeast added,incubated at 3-10C. Beer,ale S.cerevisiae As in lager;incubated at 10-21C. Converts sugar into alcohol; (top yeast) and CO2;<4%alcohol. Yeast grows at top of fermentation vessel. Sake S.cerevisiae Aspergillus oryzae converts starch Converts sugar into alcohol; in steamed rice into sugar;yeast 14-16%alcohol. added;incubated at 20C Wine,natural S.cerevisiae Strain of grape provides various flavors and Converts grape sugar into sugar concentrations.Grapes crushed into alcohol;14%or less alcohol. must;sulfur dioxide added to inhibit wild yeast;yeast added.Red wines:incubated at 25C.Aged in oak 3-5 years and in bottle 5-15 years.White wines:incubated at 10-15C.Aged 2-3 years in bottle. Wine,sparkling S.cerevisiae As natural wine,with secondary In secondary fermentation, (champagne) fermentation in bottle.2.5%sugar and yeast produces carbon dioxide; added to botled wine;incubated at 15C; yeast settles quickly. bottle inverted to collect yeast in neck. Table 28.4Yeast Fermentations Table 28.4