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Passage 2
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一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一tiny globules (小球）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 (密封倉）buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of nutrients. 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 use 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..
The significance of Brocklehurst 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
| 重點單詞 | 查看全部解釋 | |||
| bacteria | [bæk'tiəriə] |
想一想再看 |
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| contain | [kən'tein] |
想一想再看 vt. 包含，容納，克制，抑制 |
聯想記憶 | |
| lump | [lʌmp] |
想一想再看 n. 團，塊，瘤，笨重的人 |
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| keen | [ki:n] |
想一想再看 adj. 鋒利的，敏銳的，強烈的，精明的，熱衷的 < |
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| multiply | ['mʌltiplai] |
想一想再看 vt. 乘，增加 |
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| resistant | [ri'zistənt] |
想一想再看 adj. 抵抗的，反抗的 |
聯想記憶 | |
| spread | [spred] |
想一想再看 v. 伸展，展開，傳播，散布，鋪開，涂撒 |
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| mystery | ['mistəri] |
想一想再看 n. 神秘，秘密，奧秘，神秘的人或事物 |
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| liquid | ['likwid] |
想一想再看 adj. 液體的，液態的 |
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| poison | ['pɔizn] |
想一想再看 n. 毒藥，敗壞道德之事，毒害 |
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