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“When the power of love overcomes the love of power, the world will know peace” – Jimi Hendrix

Food and decay


What are the factors needed by bacteria and fungi to grow?


1) Food

2) Warmth

3) Moisture


What is the factor which is needed by plants and not needed by bacteria and fungus?


E.g. If you leave moist food in a cupboard and forget about them, they will go bad.


How do bacteria and fungus decay food?

The tiny spores (tiny reproductive cells in bacteria and fungus) of bacteria and fungi land on the foods from the air. As they grow, the bacteria and fungi produce chemicals that allow them to dissolve the foods. These chemicals can make us ill. Then we are said to have food poisoning.



Preserving food


What is meant by ‘preserving food’?

Several ways to stop or slow down the decay of foods


What are the ways of preserving foods?


a) Freezing

b) Drying

c) Chemical preservatives



Bacteria and fungi need warmth to grow. In low temperatures they stop growing.


What types of food can be preserved by freezing?


1)    Meat

2)    Fish

3)    Fruits

4)    Vegetables

5)    Fresh foods

6)    Cooked foods



Bacteria and fungi need moisture to grow. They cannot grow in dried foods which are stored in sealed containers.


What types of food can be preserved by drying?


1)    Vegetables

2)    Fruits

3)    Soup

4)    Milk

5)    Cereal

6)    Fish

7)    *Lentils

8)    *Chick peas

9)    *Beans

* Pulses (Edible seeds of various pod-bearing plants)


Chemical preservatives


Safe chemicals can be added to food to stop the bacteria and fungi from feeding and growing.


E.g. – 1) A lot of sugar is added to fruit to make jam and marmalade.

          2) Vinegar, used in pickles, is too acid for bacteria and fungi to be able to grow.

          3) A lot of salt is added when bacon is produced. 


Canning and bottling


Why will canned and bottled food last for many months or even years?


1) Some foods like fruits and vegetables are heated strongly to destroy or kill any germs such as bacteria and fungi.

2) Then the foods are sealed in airtight containers.

3) So that no more bacteria and fungi can get into the food until the can is opened.



Taking care


It is important to be careful when we handle stored or preserved food. The surface where we prepare food need to be very clean, or bacteria will spread to the foods we eat and may make us ill.


Haw fast can bacteria grow?

A bacterium can divide into two new bacteria in minutes.


Places where bacteria can stay


1) In our nose

2) In our throats

3) In our cuts and sores

4) On our skin

5) On our hands


What are the animals that can pass bacteria on to the food?


1) Mice

2) Rats

3) Flies