首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
The value of heat for the preservation of food has been known for thousands of years, but it was not realized until the nineteen
The value of heat for the preservation of food has been known for thousands of years, but it was not realized until the nineteen
admin
2012-01-05
67
问题
The value of heat for the preservation of food has been known for thousands of years, but it was not realized until the nineteenth century that a very mild heat treatment far below the boiling point, made liquid foods such as milk keep much longer. The discovery followed the work of the French scientist Louis Pasteur on wine and beer.
The process, called after him "pasteurization", is a carefully controlled mild heat treatment. It was found that the process served two purposes, it prevented the souring of milk, and it destroyed the dangerous disease germs which sometimes occur in this product.
It has long been known to bacteria experts that the tubercle bacillus is the germ in milk which host strongly resists heat treatment. To destroy this organism it is necessary to heat milk to about 60 degrees centigrade for 15 minutes, and its destruction has always been taken as a way of testing the efficiency of pasteurization. A heat treatment of this kind destroys about 99 percent of the common bacteria in milk, including nearly all those which cause milk to turn sour.
To ensure the certain destruction of tuberculosis and other disease germs in milk, it must be held at a fixed temperature for a fixed time. In Britain, for example, these conditions were defined-coy law in 1923 as 63-66 degrees centigrade for 30 minutes. This became known as the "holder" process, since the raw milk had to be pumped into a large tank, heated to just over 63 degrees centigrade, held in the tank for half an hour and then pumped out and cooled. This was a slow process and required a very large plant, so scientists worked for many years to produce a simpler, more convenient method, with less large equipment.
The latest method, officially approved in Britain in 1949, is known as the high-temperature-short-time, or H. T. S. T. method. It has now almost entirely replaced the "holder" process. In the H. T. S. T. system, the milk flows continuously through many sections of thin stainless steel pipes, During the process, the milk is held at 72 degrees centigrade for at least 15 seconds then, as it-cools, the heat is used, in part, to raise the temperature of the incoming milk in a device called a "wheat exchanger".
Efficient pasteurization may reduce the bacteria in raw milk from, say, one million to only a few thousand per cubic centimeter. The bacteria left are chemically mostly of the inert type, thatis, they either do not.
According to the passage, the new H. T. S. T. method differs from the " holder" process in ______.
选项
A、higher rate of bacteria destruction
B、different temperature requirements
C、the ease with which it is operated
D、the amount of energy preserved
答案
B
解析
第四、五段分别介绍“holder”和H.T.S.T.。通过比较可知,“holder”要求温度为63 degrees centigrade,H.T.S.T.要求72 degrees。对于杀菌效果、操作难易程度、能源利用率,作者并未对两者进行比较。
转载请注明原文地址:https://kaotiyun.com/show/ftua777K
本试题收录于:
翻译硕士(翻译硕士英语)题库专业硕士分类
0
翻译硕士(翻译硕士英语)
专业硕士
相关试题推荐
transposition
foreignexchangemarket
targetlanguage
"Gender",astheWorldHealthOrganizationdefinesit,"isusedtodescribethosecharacteristicsofwomenandmen,whichareso
GrowthEnterpriseMarket
Theideaofabalanceddietisverydifficulttoput______tosomeonewhoknowsnothingaboutfoodvalues.
Theworldisgoingthroughthebiggestwaveofmergersandacquisitionseverwitnessed.TheprocesssweepsfromhyperactiveAmer
Intermsofpurequantityofresearchanddebate,businessschoolshaveperformedamazinglyinpromotingmanagementasadistinc
Thevalueofheatforthepreservationoffoodhasbeenknownforthousandsofyears,butitwasnotrealizeduntilthenineteen
随机试题
关于银行的“风险管理部门”的说法正确的是()。
简述毛泽东行政组织思想的理论渊源。
关于心包摩擦音的叙述,不正确的是
治疗眼病、热病、神志病,宜选用的经脉是
孕妇妊娠8个月,产前来医院咨询,对母乳喂养的婴儿如何预防佝偻病的发生,以下几项中有哪一项是错误的( )。
A平肝潜阳,息风止痉B平肝潜阳,清肝明目C平肝潜阳,清热解毒D息风止痉,解毒散结E息风止痉,清肝明目蜈蚣与全蝎均具有的功效是()
可靠性原则要求企业的各项财产在取得时按实际发生的成本计量,其后各项财产如果发生了价值减损,应根据谨慎性原则计提减值准备,计提的减值准备减少资产的账面价值;如果各项财产发生的升值,应根据可靠性的原则相应调整增加财产的账面价值。()
在发票的各联次中,由收执方作为付款或收款原始凭证的称为()。
()预测是指利用各种经济因素的统计数据或它们之间的数量依存关系来推测未来事件的发展程度。
下列不正确的叙述是( )。
最新回复
(
0
)