CHAPTER 18. Food Preservation and Contamination

P 3 TERM 3
UNIT 9 FOODS AND NUTRITION

Objectives: By the end of this topic pupils should be able to: 1. Define contamination. 2. Describe ways through which food becomes contaminated. 3. Define preservation. 4. Name some foods which can be preserved. 5. Describe ways of preserving food.

Behavioural Changes:

Pupils should:

· Avoid eating contaminated food.
· Store foods properly to avoid contamination.
· Preserve suitable foods for future use.

Sub-Topics:

a) Food Preservation:

What is food?
What is food preservation?
Ways of preserving our food in our locations.

b) Food Contamination:

What is food contamination?
Ways of preventing food contamination.

Main Ideas:

· Contaminated foods can spread disease.
· Rotten food is contaminated food.
· Foods which have gone bad should not be eaten.
· Germs contaminate food through flies, dust, dirty hands and utensils.
· There are various methods of preserving food to keep it safe until it is needed.
· Foods keep longer when properly preserved.

Notes for the Teacher:

CONTAMINATION:

Contamination is the presence in food of germs, which make it go rotten or bad.

Dirty and contaminated food can cause disease.

Damp, warm and dark places favour quick multiplication of germs. Pests, such as rats, mice, cockroaches and other insects can also spoil our foods.

Faeces can contaminate our foods and make us sick. Flies and cockroaches carry germs on their feet. First they walk on faeces, then they walk on our food with their dirty feet. Germs from the flies' feet stick to the food where they grow and multiply. When you eat such food, you get sick because that food is contaminated with germs.

PRESERVATION:

Preserving food means keeping it in good condition for future use.

Meat and fish can be dried, salted, smoked, canned or frozen to keep them in good condition.

Figure

Name the most common method used in your area.

Fruits and vegetables can be dried or canned. Some fruits are made into jam and marmalade. Preserved foods keep better and longer. Millet, groundnuts, beans, peas and mushrooms can be dried and kept in sacks, grannaries or stores.

Figure

Proper cooking kills germs. Cooking is also a method of preserving food. Milk and meat should always be properly boiled and covered.

Why do we Preserve Food

1. Some foodstuffs are plenty only at certain times of the year e.g. fruits, fish, vegetables and cereals. These may be preserved so that they can be used when they are out of season.

2. Some foods have to be transported for long distances to reach all the people who need them. e.g. fruits, fish, meat, milk.

Many methods are used for preserving foodstuffs. e.g.

Heat for drying, cooking, smoking and baking.

Salt or sugar e.g. in jam or salted meat/fish.

Freezing - ice preserves food by stopping bacteria from growing.

Bottling or canning as used in fruits, meat, etc.

Moisture, warmth and darkness help germs grow.

Remove these conditions to keep food longer or to preserve it.

SOME ACTIVITIES FOR PUPILS:

· Keep bread in a damp, dark place for 2 or 3 days, and observe what happens.
· Check for food pests in cupboards, houses, stores and school compound.
· Grow moulds on bread or potatoes as an experiment. Play the game of "feel and match".
· Write up the feel and match game.
· Field trip to observe smoking of fish, or observe any other preserving processes.
· List foods that can be dried, smoked, salted, frozen, cooked, canned, bottled etc.
· Collect these foods if possible (as seeing and doing will help child remember better.
· Children visit shops and make a list of foods there.
· Collect different types of foods found in shops, markets and shambas.
· Experiment on drying in the sun.
· Salt meat and see what happens.
· Get children to find out how their parents preserve foods.

SKILLS TO DEVELOP:

Observation, Recording
Tasting, Classifying

MATERIALS REQUIRED:

· Paper, pencils and exercise books, food samples.

EVALUATION:

Questioning

Observation of children's experiment.

FOLLOW UP:

Check food stores at school and homes to see if foods are well kept.

TEST YOURSELF:

(What have you learnt from this chapter?

1. What do you understand by contamination?
2. Why is it necessary to preserve food ?
3. Describe the dangers of contaminated food.
4. Understand what can cause things to rot.