英语听力文摘 English Digest 613、酸奶中的神秘液体

 　　The Mysterious Liquid In Yogurt

 

　　When you open a container of yogurt, you’ll often see liquid collected on top. Some people mix it back into the yogurt, and others drain it off. What is it, and where does it come from?

 

　　To solve the mystery of the liquid in yogurt, let’s take a few steps back, to the milk that yogurt is made of. Milk has two different types of proteins. Most of the proteins are casein proteins, and the rest are whey proteins–of curds¹ and whey fame.

　　If you look at a glass of milk, you can’t tell the casein from the whey. But that changes when special bacteria are added to milk to make yogurt. Yogurt-producing bacteria ferment² the sugars in milk and produce an acid. As a result, the mixture is more acidic than before, and this higher acidity³ solidifies⁴ the casein proteins. The whey proteins, on the other hand, don’t solidify⁵, and separate out from the casein as liquid.

 

　　Yogurt you buy in the store has a stabilizer, usually fruit pectin, to keep the solid casein and liquid whey mixed together. But some of the whey still separates out from the casein, and that’s what you see when you open the yogurt container.

 

　　Whey contains not only proteins but also B vitamins, including riboflavin, niacin, and thiamin, which can’t be found in the solid portion of the yogurt. Because of the nutritional⁶ value of whey, your best bet is to mix it back into the rest of the yogurt, then gobble it down!

1 curds   

n.凝乳( curd的名词复数 )

参考例句：

• Little miss muffet sat on a tuffet eating some curds and whey. 小玛菲特小姐坐在垫子上，吃着凝乳和乳清。 来自互联网
• The curds contain casein, fat and minerals. 凝乳中有酪蛋白、脂肪、矿物质。 来自互联网

2 ferment   

vt.使发酵；n./vt.（使）激动，（使）动乱

参考例句：

• Fruit juices ferment if they are kept a long time.果汁若是放置很久，就会发酵。
• The sixties were a time of theological ferment.六十年代是神学上骚动的时代。

3 acidity   

n.酸度，酸性

参考例句：

• This plant prefers alkaline soil,though it will readily tolerate some acidity.这种植物在酸性土壤中也能生存，但硷性土壤更加适宜。
• Gastric acidity would not prevent the organism from passing into the gut.胃的酸度不能防止细菌进入肠道。

4 solidifies   

（使）成为固体，（使）变硬，（使）变得坚固( solidify的第三人称单数 )； 使团结一致； 充实，巩固； 具体化

参考例句：

• Jelly solidifies as it gets cold. 肉冻冷却就凝固。
• It is stirred with 10%sodium carbonate solution(50ml)and then with water (50ml), after which It'solidifies. 与10％碳酸钠溶液（50毫升）混合搅拌，然后再用50毫升水混合搅拌，从而析出固体。

5 solidify   

v.(使)凝固，(使)固化，(使)团结

参考例句：

• Opinion on this question began to solidify.对这个问题的意见开始具体化了。
• Water will solidify into ice if you freeze it.水冷冻会结冰。

6 nutritional   

adj.营养的，滋养的

参考例句：

• A diet lacking in nutritional value will not keep a person healthy.缺乏营养价值的饮食不能维持人的健康。
• The labels on food products give a lot of information about their nutritional content.食品上的标签提供很多关于营养成分的信息。