Why does cram 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 compositiona 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 emulsionstiny globules of one liquid evenly distributed throughout another. The difference lies in whats in the globules and whats 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 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 foods 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.
36.The significance of Brocklehursts research is that ________.
A) it suggested a way to keep some foods fresh without preservatives
B) it discovered tiny globules in both cream and butterwww.Examw.com
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
37.According to the researchers, cream sours fast 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
38.According to Brocklehurst, we can keep cream fresh by ________.
A) removing its fat
B) killing the bacteria
C) reducing its water content
D) altering its structure
39.The word coloniesrefers to ________.
A) tiny globules
B) watery regions
C) bacteria communities
D) little compartments
40.Commercial application of the research finding will be possible if salad cream can be made resistant to bacterial attack ________.
A) by varying its chemical composition
B) by turning it into a solid lump
C) while keeping its structure unchanged
D) while retaining its liquid form
答案:36.A 37.B 38.D 39.C 40.D
2010年6月英语六级考试的标准阅读第21篇
2010年6月英语六级考试的标准阅读第7篇
2010年6月英语六级考试的标准阅读第14篇
2010年6月英语六级考试阅读理解的训练题4
2009年12月英语六级的快速阅读答案
三大境界破解12月大学英语六级的阅读理解
2010年6月英语六级考试的标准阅读第4篇
2009年12月英语六级阅读的答案
2010年6月英语六级考试的标准阅读第40篇
09年12月英语六级阅读的难点100句3
2009年12月英语六级阅读的难点关键句100句
2010年6月英语六级考试的标准阅读第13篇
英语六级考试阅读欢度全球蓝精灵日
2010年6月英语六级考试的标准阅读第20篇
09年12月英语六级阅读的难点100句6
2010年6月英语六级考试的标准阅读第16篇
2010年6月英语六级考试的标准阅读第15篇
2010年6月英语六级考试的标准阅读第31篇
2010年6月英语六级考试的标准阅读第22篇
2010年6月英语六级考试的标准阅读第2篇
2010年6月英语六级考试的标准阅读第10篇
2010年6月英语六级考试的标准阅读第8篇
09年12月英语六级阅读的难点100句5
2009年12月大学英语六级阅读的四大难点分析
2010年6月英语六级考试的标准阅读第26的
2009年12月六级阅读的难度相对稳定
2010年6月英语六级考试的标准阅读第18篇
09年12月英语六级阅读的难点100句10
2009年12月英语六级阅读考前必备的连接词
2010年6月英语六级考试的标准阅读第9篇
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |