Preservation involves preventing the growth of microorganisms like bacteria, yeast and fungi to prevent food spoilage. It maintains the color, taste and nutrients of food. Microorganisms, enzymes and insects/rodents cause spoilage. Preservation methods remove or inactivate microbes through processes like drying, curing, refrigeration and freezing or use of chemicals like salt, sugar and vinegar. Other methods are pasteurization, radiation and packaging foods airtight. The document discusses the various preservation techniques used to extend the shelf life of foods.

2. Preservation usually involves preventing
the growth of bacteria, yeast, fungi and
other micro organisms.

3. “A process by which foods like fruits and
vegetables are prevented from getting
spoil for a long period of time. The colour,
taste and nutritive value of food is also
preserved”

5. 1. Presence of microorganism
Situations for the appropriate growth of micro
organisms-
 Food having high moisture content
 Air around the food containing
microorganisms
 Foods kept for long time at room
temperature
 Skin of fruits and vegetables getting
damaged
 Foods with low salt, sugar and acid content

6. 2. Presence of enzymes

7. 3. Insects ,worms and rats

8. 1. Removal of microorganism or
inactivating them
This is done by removing air, water,
lowering or increasing temperature,
increasing the concentration of salt or
sugar or acid in foods.

9. 2. Inactivating enzymes
-by changing conditions such as
temperature and moisture
3. Removal of insects, worms and rats
-by storing foods in dry, air tight
containers

11. 1. Drying –removing the foods water
Sun drying
Commercial drying

12.  Conventional; - heat
 Vaccum; - pulls the water out
 Osmotic;- water drawn out by osmosis
 Freeze drying; - ice crystals vaporize
 Cure –to preserve foods through the use of
salt and drying, sugar, spices or nitrates may
also be added

13. Vinegar
Edible coating-natural wax, oil, petroleum
based wax

15. The elimination of all micro organisms
through extended boiling or through the
use of certain chemicals.

16. Refrigeration
Freezing

17. Pasteurization- heat liquids to 160 degree
celsius for 15 seconds
Ohmic heating- electrical current is passed
through the food generating enough heat
to destroy micro organisms.

18. Low doses of gamma rays, x rays, or
electrons

19. Exposes food to intense, very brief flashes
of light which disrupt the cell membrane of
bacterial cells.

20. Inactivates food borne micro organisms at
low temperature

21. Uses ultra high pressure to inhibit the
chemical process of food deterioration.

22. Ozone is commercially produced by
exposing oxygen to electrical current.
Ozone is an effective disinfectant

23. Foods are packaged airtight by a
commercial sealing process