【正文】 suitable for brewing, Saccharomyces yeasts are incapable of hydrolyzing starches and dextrins. Use of starchbased materials for alcoholic fermentations requires addition of exogenous enzymes such as αand βamylase of malt or microbial enzymes such as αamylase, amyloglucosidase ( glucoamylase) and pullulanase. Lesson 2 Alcoholic Beverages 除了不適合于釀造的糖化酵母外，其他的酵母菌屬不能水解淀粉和糊精。 譯文 Part 2 食品科技英語的閱讀 The major sugars of grape juice are glucose and fructose and since preferentially metabolizes the glucose, any unfermened sugar left in the resulting wine is contrast,Sauterne wine yeasts ferment fructose faster than glucose. Lesson 2 Alcoholic Beverages 葡萄汁中的主要糖類 為葡萄糖和果糖， 由于啤酒酵母優(yōu)先代謝葡萄糖，因此在葡萄酒發(fā)酵中留下的一些非發(fā)酵糖是果糖。 譯文 Part 2 食品科技英語的閱讀 Brewer’s wort, produced from barley malt contains 19 amino acids and a range of other nutrients. These amino acids are assimilated at different rates during fermentation. A general amino acid permease (GAP ) can transport all basic and neutral amino acids except proline. At least 11 other more specific amino acid transport systems exist in yeast. Proline permease is repressed by other amino acids and ammonia. Lesson 2 Alcoholic Beverages 用大麥芽制作的 釀造麥芽汁 含有 19種氨基酸和其它各種營養(yǎng)素。一種常見的氨基酸透性酶能運輸除脯氨酸之外的所有堿性和中性氨基酸。 脯氨酸透性酶 被其它氨基酸和氨抑制了活性。 釀造麥芽汁 中的固醇和不飽和脂肪酸含量通常低于最佳水平。 譯文 Part 2 食品科技英語的閱讀 Many strains of S. cerevisiae can attain ethanol concentrations of 1214%. Interest has developed in the use of high alcohol tolerant yeasts in highgravity brewing processes and in alcohol production for distillation with a view to increasing plant productivity and decreasing distillation costs. Lesson 2 Alcoholic Beverages 許多啤酒酵母菌株 能積累乙醇達到 12%14%的濃度。 譯文 Part 2 食品科技英語的閱讀 Selected strains are able to produce 1820% alcohol although fermentation rate is generally greatly reduced as ethanol concentration increases. Grape juices with very high sugar concentrations are only fermented by osmophilic yeasts such as Saccharomyces rouxii and Saccharomyces bailli which have a high capacity to ferment fructose. Lesson 2 Alcoholic Beverages 選擇菌株 的發(fā)酵速率通常隨著乙醇濃度的增加而大大降低，但這些菌株仍能產生 1820%的乙醇。 譯文 Part 2 食品科技英語的閱讀 Plasma membrane phospholipid position is important for ethanol tolerance. Increased ethanol tolerance is observed when membrane unsaturated fatty acid content is increased. Alcohol tolerance may be enhanced by supplementing the growth medium with unsaturated fatty acids, vitamins and proteins. Lesson 2 Alcoholic Beverages 細胞膜的磷脂成分 對菌種的耐乙醇能力很重要。補充培養(yǎng)基中的不飽和脂肪酸、維生素和蛋白質也可增強菌種的 耐乙醇能力 。有資料表明酵母的糖酵解酶已糖激酶、甘油醛 3磷酸脫氫酶和丙酮酸脫羧酶對乙醇濃度敏感。在此范圍內， pH高，發(fā)酵活性高；但在 34間沒有明顯變化。高 pH值可增加甘油的產量。 譯文 Part 2 食品科技英語的閱讀 Since most bacteria, with the exception of acetic acid and lactic acid bacteria, prefer more neutral pH values the susceptibility of wine musts to infection is greatly reduced. Lesson 2 Alcoholic Beverages 除了乙酸菌和乳酸菌外，大多數的細菌都喜歡較中性的 pH，從而使葡萄汁對細菌感染的敏感性大為降低。在 1535℃ 范圍內，發(fā)酵速度一般隨溫度增加而增加；發(fā)酵液中的甘油、丙酮、 23丁二醇、乙醛、丙酮酸鹽和酮戊二酸鹽的含量也隨溫度而增加。 譯文 Part 2 食品科技英語的閱讀 With white wines, lower fermentation temperatures produce fresher and more fruity wines, and the risk of bacterial infection and resultant volatile acid production is reduced. Higher temperatures of 2230℃ are used for production of red wines, fermented on the skins, leading to increased colour extraction and production of a rich aroma. Lesson 2 Alcoholic Beverages 對白葡萄酒來說， 發(fā)酵溫度低 ，產生的酒更新鮮、果味更濃；低溫度也增加了細菌污染的機會，導致揮發(fā)性酸量降低。 譯文 Part 2 食品科技英語的閱讀 Lesson 2 Alcoholic Beverages 課堂小結 ?熟練掌握關于酒精飲料的相關詞匯； 如： theoretical yields(理論產量 ),barely malt(大麥芽 )， basic amino acids(堿性氨基酸 )等 ?掌握常用句型的表達技巧； 如： respcetively 的運用； sth is reduced as sth increases.