Increasingly, over the past ten years, people—especially young people—have become aware of the need to change their eating habits, because much of the food they eat, particularly foods, is not good for the health. Consequently, there has been a growing interest in natural foods: foods which do not contain chemical additives and which have not been affected by chemical fertilizers, widely used in farming to- day.
Natural foods, for example, vegetables, fruits and grains which have been grown in soil that is rich in organic matter. In simple terms, this means that the soil has been nourished by unused vegetable matter, which provides it with essential vitamins and minerals. This in itself is a natural process compared with the use of chemicals and fertilizers, the main purpose of which is to increase the amount—but not the quality—of foods grown in commercial farming areas.
Natural foods also include animals which have been allowed to feed and move freely in healthy pastures. Compare this with what happens in the mass production of poultry: there are battery farms, for ex- ample, where thousands of chickens live crowded together in one building and are fed on food which is little better than rubbish. Chickens kept in this way are not only tasteless as food; they also produce eggs which lack important vitamins.
There are other aspects of healthy eating which are now receiving increasing attention from experts on diet. Take, for example, the question of sugar, this is actually a non-essential food! Although a natural alternative, such as honey, can be used to sweeten food if this is necessary, we can in fact do without it. It is not that sugar is harmful in itself. But it does seem to be an additive: the quantity we use has grown steadily over the last two centuries and in Britain today each person consumes an average of 200 pounds a year! Yet all it does is provide us with energy, in the form. of calories. There are no vitamins in it, no minerals and no fibre.
It is significant that nowadays fibre is considered to be an important part of a healthy diet. In white bread, for example, the fibre has been removed. But it is present in unrefined flour and of course in vegetable. It is interesting to note that in countries where the national diet contains large quantities of unrefined flour and vegetable, certain diseases are comparatively rare. Hence the emphasis placed on the eating of wholemeal bread and more vegetables by modern experts on healthy eating.
Recently, some people are interested in natural foods because ______.
A．these foods are fresh and sweet
B．they want to change their eating habits
C．these foods do not contain chemical additives and have not been affected by chemical fertilizers
D．they don't like the processed foods
Food which is kept too long decays because it is attacked by yeasts （酵母菌), moulds （霉)
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 deteriorates during storage because ______.
A．necessary chemical preservatives are totally absent from it
B．it is infected with yeasts, moulds and bacteria
C．heat sterilization destroys infections present in it
D．it isn't fit for storage
