DRY FOOD – Dried Food
Food contains proteins, carbohydrates, fats and vitamins and these are vital to life. Food must be fresh when we eat it. If it is bad, it can make us ill. There are two main agents which turn food bad; fungi (such as yeast and various moulds) and bacteria. These are micro-organisms which cannot make their own food. So they live and grow on our food.
Moulds, for example, usually grow on bread. Yeast can spoil fresh food but it also has some very useful properties. For hundreds of years people have used it in the making of bread and wine. In order to grow and multiply, all these micro-organisms need food, water, warmth and, in some cases, air. The methods we use to preserve our food make conditions dry and very cold; unsuitable for the growth and multiplication of micro-organisms.
The great distances which often separate the producer of food from the consumer in the 20th century make effective food preservation vital. But most preservation processes destroy many important vitamins and proteins. One of the tasks of food technologists today is to find ways of preserving food without losing these important substances.
In hot countries people dry food simply by the heat of the sun. In this way, it is possible to reduce the moisture level in most fruits to between 5% and 15%. This level is low enough to stop the growth of micro-organisms. Some other kinds of food go through a process called dehydration. In this process, hot and dry air passes over the food and absorbs as much moisture as possible. This method is usually used for drying tea and coffee.
Another way of preserving food is putting it into cans or bottles and heating it up to a temperature of 100°C or 120°C for about ten minutes because high temperatures kill micro-organisms in food. There are several other ways of preserving food. One of them is freezing the food to a temperature between -30°C and -40°C.
Some people still use two very old methods: salting and smoking. Salt stops the growth of micro-organisms and smoking removes some of the moisture in the food. Certain acids and chemicals are useful preservers because they stop the action of micro-organisms. For example, we can use vinegar, an acidic liquid, to preserve eggs, onions and some vegetables.
One of the newest methods is radiation. It is very effective because it kills not only the micro-organisms but also their spores (small cells which fungi or other micro-organisms produce in order to reproduce the organism). In this way, it stops their reproduction.
Mark the best choice.
1 .Line 8, ‘it’ refers to . a) fresh food b) yeast c) bread d) mould
2. Lines 19-20, ‘these important substances’ refers to . a) ways of preserving food b) one of the tasks of food technologists c) vitamins and proteins d) most preserving methods
3. Line 28, ‘if refers to . a) food b) tea c) coffee ‘ d) this method