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
56
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, pasteurization refers to ______.
选项
A、the heat treatment of milk
B、heating liquid to 100 degrees centigrade
C、the heat treatment to destroy all the common bacteria
D、heating objects to a fixed temperature for a fixed time
答案
D
解析
由第一、二段可知,pasteurization即巴氏杀菌法,是指对食物进行a carefully controlled mild heat treatment,即加热到一定温度并持续一段时间以杀死可能导致疾病的微生物的过程。
转载请注明原文地址:https://jikaoti.com/ti/PzwUFFFM
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
knowledgeeconomy
acknowledge
theEUsinglemarket
Whatabundleofcontradictionsisaman!Surely,humoristhesavinggraceofus,forwithoutitweshoulddieofvexation.Wit
Writeacompositionoflessthan400wordsonthegiventopicbelow.China’sEnvironmentChallengedbyRapidEconomicGrowth
Itisnot______muchthelanguageasthebackgroundthatmakesthebookdifficulttounderstand.
Carletonwouldstillrankamongthegreat______:ofnineteenthcenturyAmericanartevenifthecircumstanceofherlifeandca
Correctionofthestudent’saberrantpronunciationisacontinual,on-goingprocess,notsomethingreservedforlessonsorexerc
Theworldisgoingthroughthebiggestwaveofmergersandacquisitionseverwitnessed.TheprocesssweepsfromhyperactiveAmer
Theproblemisthatmostlocalauthoritieslackthe______indealingwiththefinancialproblems.
随机试题
大量腹腔积液的体征包括
人体内嘌呤核苷酸分解代谢的主要终产物是
DNA分子中的碱基组成是
A.头孢西丁B.亚胺培南C.氨曲南D.拉氧头孢E.克拉维酸属于p一内酰胺酶抑制剂的抗菌药是
沥青PG分级是美国SHRP计划中提出的沥青性能分级标准,它是依据沥青的路用性能进行分级。()
生产经营单位从业人员的权利不包括()。
下列选项中,满足有效利率与名义利率的差值最大的是( )。
公司制期货交易所董事长因故临时不能履行职权的,由董事长指定的副董事长或者董事代其履行职权。( )
具有期货等金融或者法律、会计专业硕士研究生以上学历的人员,申请期货公司董事、监事和高级管理人员任职资格的,从事除期货以外的其他金融业务,或者法律、会计业务的年限可以放宽( )年。
求极限
最新回复
(
0
)