Question

【題目】Why does cream go bad faster than butter? Some researchers think they have the answer, and it comes down to the structure of the food, not its chemical composition — a finding that could help rid some processed foods of chemical preservatives.

Cream and butter contain pretty much the same substances, so why cream should sour much faster has been a mystery. Both are emulsions — tiny globules(小球體) of one, liquid evenly distributed throughout another. The difference lies in what's in the globules and what's in the surrounding liquid, says Brocklehurst, who led the investigation.

In cream, fatty globules drift about in a sea of water. In butter, globules of a watery solution are locked away in a sea of fat. The bacteria which make the food go bad prefer to live in the watery regions of the mixture. “This means that in cream, the bacteria are free to grow throughout the mixture，” he says.

When the situation is reversed, the bacteria are locked away in compartments(分隔間) buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of nutrients(養(yǎng)料). They also slowly poison themselves with their waste products: “In butter, you get a self－limiting system which stops the bacteria growing，” says Brocklehurst.

The researchers are already working with food companies keen to see if their products can be made resistant to bacterial attack through alterations to the food's structure. Brocklehurst believes it will be possible to make the emulsions used in salad cream, for instance, more like that in butter. The key will be to do this while keeping the salad cream liquid and not turning it into a solid lump.

【1】The significance of Brocklehurst's research is that ________.

A. it suggested a way to keep some foods fresh without preservatives

B. it discovered tiny globules in both cream and butter

C. it revealed the secret of how bacteria multiply in cream and butter

D. it found that cream and butter share the same chemical composition

【2】According to the researchers, cream sours faster than butter because bacteria ________.

A. are more evenly distributed in cream

B. multiply more easily in cream than in butter

C. live on less fat in cream than in butter

D. produce less waste in cream than in butter

【3】The underlined word “colonies” (Line 2, Para 4) refers to ________.

A. tiny globules

B. watery regions

C. bacteria communities

D. little compartments

Answer 1

【答案】the bacteria are locked away .C選項(xiàng)C. bacteria communities細(xì)菌群

【解析】為什么奶油比黃油更容易變質(zhì)。研究人員發(fā)現(xiàn)這是由于食物結(jié)構(gòu)決定的，因此要改變食物結(jié)構(gòu)，目的就是減緩細(xì)菌繁衍速度、增加保鮮能力，可減少防腐劑的使用。

【1】細(xì)節(jié)理解題。根據(jù)第一段最后一句所說(shuō)的finding that could help rid some processed foods of chemical preservatives.，減少防腐劑的使用。對(duì)應(yīng)A項(xiàng)中Keep some foods fresh without preservatives，故選A。

【2】推理判斷題。根據(jù)第三、四段，細(xì)菌在奶油里比在黃油里更容易存活，由此推斷出細(xì)菌在奶油里比在黃油里容易繁殖。故選B。

【3】詞義猜測(cè)題。結(jié)合第四段第一、二句：第一句的主句主語(yǔ)是bacteria，第二句的individual colonies必然指代bacteria。再者第四段主要介紹黃油不易腐敗的原因——細(xì)菌被油脂鎖住，不易繁殖。故選C。