Food preservation technologies

Context

SCIENCE/ Food preservation technologies, good to combine with

methods of cooking

kitchen hygiene and safety

healthy nutrition, nutritional deficiency diseases

Cells and Micro-organisms

Jokers of interest

Practical lesson

LESSON

What is food preservation?

The process of keeping food free from micro-organisms so that it can be kept longer.

What is a preservative?

A substance used for food preservation.

 What are foods that can be preserved?

Foods that can be preserved are fruits, vegetables, fish and meat.

Why is food preservation important?

• To prevent spoilage and decay.
• To avoid wastage of food
• To improve the flavour, colour and texture
• To make food available throughout the year

Food preservation technologies and how they work

a)      Sun drying

b)     Salting
= The water in the food is removed (by strong sunlight or salt)

c)      Smoking
= Smoke (= a preservative) destroys micro-organisms in the food.

d)     Freezing/ Refrigeration
= low temperature inactivates micro-organisms.

e)      Canning and bottling
= food is heated, air is removed, cans are sterilised and sealed, preservatives are added.
Foods that can be canned or bottled are fruits, fruit juices, milk, beans, fish and meat.

f)       Jam making
= Sugar kills micro-organisms. The jam is boiled and the jars are sealed to cut off air completely.
Jam can be made of any type of fruits.

Vocabulary help Chichewa

Moisture = chinyezi

Smoke = utsi

Salt = mchere

To draw out, draws out = kuchotsa, imachotsa

inactivate = chosagwira ntchito

Activity: Making jam!!!

I was so lucky to have a papaya tree in my backyard. So I picked 3 papayas and took them to class. We distributed the following tasks: (Some learners were just watching)

-         Washing papayas

-         Peeling and cutting papayas into small pieces

-         Preparing the charcoal burner

INSTRUCTIONS

Making jam is very easy:

• You cut the fruit into very small pieces.
• Then you boil them in a pot. You can add only a little bit of water, but you have to add a LOT of sugar. Have it boiling for 20 – 30 minutes. The fruit pieces become soft and release liquid.
• Now you can smash them with whatever kitchen tools you have available.
• Prepare some glass jars. Wash them with boiling hot water so that there are no micro-organsims remaining. Then you fill in the hot jam. Seal the jars quick, then turn them upside down and let them cool down.
• Ready is your jam!

My learners really enjoyed the activity – and the jam sandwiches of course…!

Exercise

1)      Which of the following preservation technologies removes water from the food?

A.     canning

B.     salting

C.     bottling

D.     freezing

2) Which of the following preservation technologies inactivates micro-organisms with low temperatures?

1. salting
2. bottling
3. freezing
4. jam making

3) Which of the following preservation technologies requieres a lot of sugar?

1. freezing
2. jam making
3. salting
4. sun drying