Question

【题目】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(小球体) 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(分隔间) buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of nutrients(养料). 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选项C. bacteria communities细菌群

【解析】为什么奶油比黄油更容易变质。研究人员发现这是由于食物结构决定的，因此要改变食物结构，目的就是减缓细菌繁衍速度、增加保鲜能力，可减少防腐剂的使用。

【1】细节理解题。根据第一段最后一句所说的finding that could help rid some processed foods of chemical preservatives.，减少防腐剂的使用。对应A项中Keep some foods fresh without preservatives，故选A。

【2】推理判断题。根据第三、四段，细菌在奶油里比在黄油里更容易存活，由此推断出细菌在奶油里比在黄油里容易繁殖。故选B。

【3】词义猜测题。结合第四段第一、二句：第一句的主句主语是bacteria，第二句的individual colonies必然指代bacteria。再者第四段主要介绍黄油不易腐败的原因——细菌被油脂锁住，不易繁殖。故选C。