【正文】 利用 2230℃ 范圍的發(fā)酵高溫進(jìn)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。 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 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(xì)胞生長來說，都有不同的 適宜的溫度 。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。 pH可影響副產(chǎn)物的形成。 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。 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(jìn)料的方法、細(xì)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。升高細(xì)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。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。考慮到增加產(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(qiáng)的酵母的利用產(chǎn)生越來越強(qiáng)的 興趣 。但是，若向培養(yǎng)基中增添油酸和齊墩果酸，對氧的需求就會消失。 譯文 Part 2 食品科技英語的閱讀 while alcoholic fermentations are largely anaerobic, some oxygen is needed to enable the yeast to synthesize some sterols and unsaturated fatty acid membrane ponents. Brewer’s wort normally contains suboptimal levels of sterols and unsaturated fatty acids, but if the medium is supplemented with oleic or oleanoic acid, the requirement for oxygen disappears. Lesson 2 Alcoholic Beverages 雖然酒精發(fā)酵主要是在厭氧的環(huán)境中，但仍需要一些 氧 來促進(jìn)酵母細(xì)胞合成某些固醇和不飽和脂肪酸等細(xì)胞膜成分。在酵母細(xì)胞內(nèi)，至少還存在其它 11種更加特定的 氨基酸轉(zhuǎn)運(yùn)系統(tǒng) 。在發(fā)酵期間， 這些氨基酸 以不同速率被吸收利用。相反，白葡萄酒酵母發(fā)酵時果糖比葡萄糖快得多。以淀粉為底物進(jìn)行酒精發(fā)酵需要添加外源酶，如麥芽中的 α和 β淀粉酶或微生物中的 α淀粉酶，葡萄糖苷酶和支鏈淀粉酶。與啤酒酵母不同， 脆壁克魯維酵母和乳酸克魯維酵母 這兩種酵母能發(fā)酵乳糖，它們含有乳糖透性酶系統(tǒng)，可將乳糖轉(zhuǎn)運(yùn)至胞內(nèi)，從而能夠?qū)⑷樘撬鉃槠咸烟呛桶肴樘沁M(jìn)入糖酵解途徑。 麥芽糖和麥芽三糖 在細(xì)胞內(nèi)被a–葡萄糖苷酶水解。位于胞外周質(zhì)空間的轉(zhuǎn)化酶首先水解 蔗糖 。 我們認(rèn)為 絮凝作用 是由于鈣離子和細(xì)胞壁羧基基團(tuán)之間形成的鹽橋而產(chǎn)生的。雖然細(xì)胞壁是一種半硬質(zhì)性的，但其可溶的滲透性結(jié)構(gòu)能夠賦予酵母相當(dāng)?shù)目箟汉涂箯垙?qiáng)度。形成的 ATP用于滿足其他細(xì)胞的能量需要?？偡磻?yīng)式如下： 譯文 Over 96% of fermentation ethanol is produced using strains of Saccharomyces cerevisiae or species related to it, particularl Saccharomyces uvarum. Ethanol is produced by the EmbdenMeyerhofParnas(EMP) pathway. Pyruvate,produced during glycolysis is converted to acetaldehyde and ethanol. The overall effect is summarized as follows: Part 2 食品科技英語的閱讀 Theoretical yields from 1g glucose are ethanol and ,in practice, approximately 10% of the glucose is converted to biomass and yields of ethanol and CO2 may reach 90% of theoretical values. The ATP formed is used to supply other cell energy requirements. Lesson 2 Alcoholic Beverages 理論上， 1g葡萄糖可產(chǎn)生 CO2。 EMP途徑是產(chǎn)生酒精的代謝途徑。 一些著名的強(qiáng)化酒 包括雪利酒、波爾圖葡萄酒和馬德拉葡萄酒。 譯文 Part 2 食品科技英語的閱讀 Other distilled beverages, such as vodka and gin, are produced from neutral spirits obtained by distillation of fermented molasses, grain, potato or whey. A variety of fortified wines are produced by addition of distilled spirit to wines to raise the alcohol content to 1520%. Notable products include sherries, Port and Madeira wines. Lesson 2 Alcoholic Beverages 其它蒸餾類飲料 如伏特加和杜松子酒，是從發(fā)酵過的糖漿、谷物、馬鈴薯或乳清中提純酒精而生產(chǎn)的。 下周四交（請在作業(yè)本上抄寫指定英文原文并翻譯）