Topic 3: How to preserve food and maintain its nutrients

Food Preservation

Food preservation is a method to make food last longer without getting spoiled. The principles of preservation is to destroy some species of microorganism, prevent microorganisms from growing, prevent or slow down the processes of enzymes from breaking down the food.

1. Dehydrating

is to remove the water from the food, so that microorganisms will not be able to grow, e.g. drying, baking and smoking. These foods can easily be dehydrated: banana, fish, shrimp, etc.

2. Pickle

is to use salt and lactic acid to inhibit the growth of microorganisms, which cause the food to spoil. Pickles can be soured, salted or sweetened pickle such as pickled Chinese cabbage, salted egg, pickled fruit etc.

3. Cooking

uses heat to destroy microorganisms and preserve them for long time,

such as sliced sheets dried pork, crispy pork and dried shredded pork.

4. Canning and bottling

is to seal the food in containers which are tightly closed to prevent microorganisms from entering the containers. Heat is used to destroy germs that came withthe vegetable or fruit.

5. Freezing

is to pack the food and keep it at subzero temperature so microorganisms cannot grow.

6. Irradiation

is to expose vegetables, fruits or seeds to gamma radiation. The radiation will destroy enzymes and fungi in the food and so stop their growth and germination. Irradiation also destroys insect’s eggs, parasites and microorganisms, so that the food can be stored for long time.

Advantages of preservation

1. Food can be stored for a long time.

2. Food can be kept without getting spoiled during transportation.

3. Saving the cost of repurchasing food since some of it is likely to expire before it is consumed; keeping the food fresh and ready to be eaten or cooked.

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