【正文】 lic Beverages 許多啤酒酵母菌株 能積累乙醇達到 12%14%的濃度?？紤]到增加產(chǎn)量和降低蒸餾成本，在高比重釀造過程和酒精蒸餾中，人們對耐酒精能力強的酵母的利用產(chǎn)生越來越強的 興趣 。 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(chǎn)生 1820%的乙醇。含糖濃度極高的 葡萄汁 僅能用耐滲透壓酵母如魯酵母和發(fā)酵，這兩種菌發(fā)酵果糖的能力高。 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。升高細胞膜的不飽和脂肪酸含量，可觀察到菌種的耐乙醇能力提高。補充培養(yǎng)基中的不飽和脂肪酸、維生素和蛋白質(zhì)也可增強菌種的 耐乙醇能力 。 譯文 Part 2 食品科技英語的閱讀 Physiological factors such as method of substrate feeding, intracellular ethanol accumulation, osmotic pressure, and temperature all contribute to yeast ethanol tolerance. Yeast glycolytic enzymes hexokinase, gluceraldehydes3phosphate dehydrogenase and pyruvate decardboxylase have been shown to be sensitive to ethanol concentration. Lesson 2 Alcoholic Beverages 生理因素如底物進料的方法、細胞內(nèi)乙醇的積累、滲透壓和溫度都有助于改善酵母的乙醇耐受力。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。 譯文 Part 2 食品科技英語的閱讀 For yeasts, pH values between 3 and 6 are most favourable for growth and fermentation activity. Fermentation activity is higher at higher pH values and there is a noticeable lag in fermentation activity at pH 34. pH affects formation of byproducts. High pH values increase glycerol formation. The pH of grape must is usually in the range because of its high acid content (515g/l), mainly tartaric and malic acids. Lesson 2 Alcoholic Beverages 對于酵母來說， pH值在 36之間，對生長和發(fā)酵活性是最適宜的。在此范圍內(nèi)， pH高，發(fā)酵活性高；但在 34間沒有明顯變化。 pH可影響副產(chǎn)物的形成。高 pH值可增加甘油的產(chǎn)量。葡萄汁的 pH一般在 ，因為其主要含酒石酸或蘋果酸而表現(xiàn)出的高酸度 515g/l。 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(shù)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。 譯文 Part 2 食品科技英語的閱讀 Temperature optima are distinctly different for yeast fermentation, yeast respiration and cell growth. Fermentation rate generally increase with temperature in the range 1535℃ and glycerol, acetone, butane23diol, acetaldehyde, pyruvate and 2ketoglutarate levels increase in the fermentation broth. Formation of higher alcohols is also temperaturedependent. Lesson 2 Alcoholic Beverages 對酵母的發(fā)酵、呼吸和細胞生長來說，都有不同的 適宜的溫度 。在 1535℃ 范圍內(nèi)，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。 高級醇的形成也是隨溫度而變的。 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(chǎn)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(dǎo)致?lián)]發(fā)性酸量降低。利用 2230℃ 范圍的發(fā)酵高溫進行表面發(fā)酵生產(chǎn)的紅葡萄酒， 酒體色澤 顏色增加且富有香氣。 譯文 Part 2 食品科技英語的閱讀 Lesson 2 Alcoholic Beverages 課堂小結(jié) ?熟練掌握關(guān)于酒精飲料的相關(guān)詞匯； 如： theoretical yields(理論產(chǎn)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.