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The truth about canning
罐头为什么保质期这么长？
During the mid-19th century, canned food became a status symbol among middle-class households in Europe, being something of a frivolous novelty.
在19世纪中叶，罐头食品作为一种令人着迷的新鲜事物，成为欧洲中产阶级家庭的地位象征。
Increasing mechanization of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for canned food.
罐头加工技术的提高，加上城市人口的大幅增加，导致欧洲对罐头食品的需求不断增长。
A number of inventions and improvements followed, and by the 1860s, smaller machine-made steel cans were possible, and the time to cook food in sealed cans were reduced from around six hours to 30 minutes.
许多的发明和改进随之而来。到 1860 年代，小机器制造的钢罐也投入使用，而加工密封罐装食物的时间从大约六个小时减少到三十分钟。
To prevent the food from being spoiled before and during containment, a number of methods are used: pasteurization, boiling (and other applications of high temperature over a period of time), refrigeration, freezing, drying, vacuum treatment, antimicrobial agents that are natural to the recipe of the foods being preserved, a sufficient dose of ionizing radiation, submersion in a strong saline solution, acid, base, osmotically extreme (for example very sugary) or other microbially challenging environments.
为了防止食品在密封之前和密封期间变质，人们使用了许多方法：巴氏杀菌、煮沸（以及其它在单位时间内达到高温的手段）、冷藏、冷冻、干燥、真空处理、使用对保存食品配方天然的抗菌剂、足够剂量的电离辐射、将食物浸入强盐溶液中、或使用酸、碱渗透极端环境（例如非常含糖）或其他微生物难以生存的环境。
Other than sterilization, no method is perfectly dependable as a preservative. For example, the spores of the micro-organism Clostridium botulinum (which causes botulism) can be eliminated only at temperatures above the boiling point of water.
除了灭菌之外，没有任何方法能像加防腐剂一样完全可靠。例如，微生物肉毒梭菌（引起肉毒杆菌中毒）的孢子只能在高于水沸点的温度下消除。
本文转载自中国日报网，如有侵权，请联系我们删除。
