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  3. Food which is kept too long decays because it is attacked by yeasts (酵母菌), moulds (霉) and bacteria (细菌). The canning process, ho

Food which is kept too long decays because it is attacked by yeasts (酵母菌), moulds (霉) and bacteria (细菌). The canning process, ho

admin2010-05-26  76
问题     Food which is kept too long decays because it is attacked by yeasts (酵母菌), moulds (霉) and bacteria (细菌). The canning process, however, seals the product in a container so that no infection can reach it, and then it is sterilized (消毒) by heat. Heat sterilization destroys all infectious present in food inside the can. No chemical preservatives are necessary, and properly canned food does not deteriorate during storage.
    Today vegetables, fish, fruit, meat and beer are canned in enormous quantifies. Foods that were previously seasonal may now be eaten at any time, and strange foods are available far from the countries where they are grown. The profitable crops many farmers now produce often depend on the proximity (邻近) of a canning factory.
    The first stage in the canning process is the preparation of the raw food. Diseased and waste portions  are thrown away; meat and fish are cleaned and trimmed; fruit and vegetables washed and graded for size. The jobs are principally done by machine
    The next stage, for vegetables only, is blanching. This is immersion (浸洗) in very hot or boiling  water for a short time to remove air and soften the vegetable. This makes it easier to pack into cans for sterilization. Some packing machines fill up to 400 cans a minute. Fruit, fish and meat are packed mw and cold into cans, and then all the air is removed. When the cans are sealed, the pressure inside each can is only about half the pressure of the outside air. This is "vacuum" packing.
    During the sterilization process which follows, the cans are subjected to steam or boiling water, with the temperature and duration varying according to the type of food. Cans of fruit, for example, take only 5-10 minutes in boiling water, while meat and fish are cooked at higher temperature for longer periods. After sterilization, the cans are cooled quickly to 32℃, to prevent the contents from becoming too soft.
    The final stage before dispatch to the wholesale or retail grocer is labeling, and packing the tins into boxes. Nowadays, however, labeling is often printed on in advance by the can maker and no paper  labels are then required.
Food canning technology makes it possible to______.
选项 A、increase the amount of food products.
B、make food more delicious
C、eat previously seasonal food at any time
D、grow strange plants
答案C
解析 本题需查读第二段。罐装食品技术使本来是季节性的食物在任何时候都能吃到，并非能增加食物的产量，使食物更好吃，或种植奇特的植物。
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