Food preservation


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Food preservation

  2. 2. Bottling and canning are processes of preserving food by heating and then sealing it in an airtight container.The food is boiled to kill microorganisms and then sealed to prevent other microorganisms from getting in.
  3. 3. Pickling food in vinegar or other acids, makes it difficult for microorganisms to live. Commonly pickled food include onions, parkias, soya beans and chillies.
  4. 4. Sugar can also be used in pickling fruits such as nutmegs, mangoes and cherries.The concentrated sugar solution used draws water from the fruit thus preventing the growth of microorganisms.
  5. 5. A lot of food is preserved by drying under the sun.Drying removes most water from food. Most bacteria die or become inactive when the food is dried.
  6. 6. Anchovies and dried chillies are examples of dried food
  7. 7. A lot of fruit such as raisins, guavasand papayas can be eaten dried.
  8. 8. Salting is an age-old way of preserving food. The salt draws out moisture and prevents microorganisms from growing. In this process, food such as fresh fish are gutted, washed and coarse salt is rubbed into it.
  9. 9. A lot of our local foods are preserved by salting process.
  10. 10. Vacuum packing keeps food by sucking air out from its packaging.Food is thus prevented from spoiling because there is no air.
  11. 11. Vacuum paching is commonly used for storing nuts, sliced fish, pickled and dried fruit.
  12. 12. Cooling and freezing are the most common forms of food preservation.
  13. 13. Cooling slows down the action of microorganisms, thus it takes longer to spoil. It allows fruit from different parts of the world to appear on our supermarket shelves.At freezing temperature, microorganisms become inactive, thus food cannot spoil when it is frozen.
  14. 14. Food like meat, fruit and vegetables are kept in the refrigerator.
  15. 15. Waxing of fruit and vegetables is also common. Apples, oranges, eggplants and tomatoes are dipped into liqiud wax to prevent growth of fungi and loss of moisture.Waxed fruit need to be washed thoroughly or peeled before eating.
  16. 16. Pasteurization means heating food to a certain temperature for some time followed by rapid cooling. Heating at such high enough temperature kills most bacteria. However, it does not affect the taste and nutritional value of the food.
  17. 17. Fresh milk, yoghurt drink and juices are pasteurized to make them last longer.
  18. 18. As food is heated and cooked, the heat kills the microorganisms,Boiling kills most bacteria. However, those not affected by heat will grow when the conditions are suitable. Boiling kills bacteria
  19. 19. Smoking is the process of drying food with smoke for a long period of time. This method is mainly used for fish, meat and fruit such as banana.The drying effects of smoke and the chemicals produced from the smoke help to preserve the food.Smoked banana smoked meat
  20. 20. Food preservation is a process of slowing down food from becoming bad.Besides making the food lasts longer, preservation also prevents food wastage.
  21. 21. Food preservation also allows food to be eaten out of season. It gives variety and nutrition to our diet all year round.Freeze-dried food are easy to store and transported because they are light and require less space.
  22. 22. Durians, rambutans and starfruits can be preserved in different ways.Instant coffee, milk powder and curry poweder are freeze-dried.