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and graded for size. The jobs are principally done by machine.
The next stage, for vegetables only, is blanching. This is immersion
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 raw 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 temperatures for longer period. After sterilization, the
cans are cooled quickly to 32℃ to prevent the contents from becoming
too soft.
The final stage before dispatch (发送) 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.
1. The main idea of Para.1 is
A) Food scientifically sealed in cans
is safe from decay.
B) Sterilization -- the key to the safe-keeping of food.
C) The use of chemicals in preventing the decay of food.
2. The main idea of Paras. 2 and 3 is
A) The history and early methods of preserving food.
B) The French influence in food canning.
C) The scientific principles of food canning.
3. The main idea of Para. 4 is
A) How the canning industry affects our lines.
B) The economic effects of the canning industry.
C) The range and diverse advantages of canned food.
4. The main idea of Paras. 5-8 is
A) The mechanical miracle of food canning.
B) The step-by-step modern processes of canning food.
C) The process of preparing, washing and grading food for canning.
KEY: A, A, C, B
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