SAASTE Technology/Activities/Preservation-1

Processing

Grade 6

Preservation
Materials deteriorate in different ways. Some get moldy (bread), some dry out and crack (wood), some go sour (milk), some rust (steels), etc. In the case of food it is micro-organisms that cause it to go bad. When we preserve materials we can prolong its lifespan or in some cases prevent it from deteriorating.

This activity will show us one method of preserving a food material:

You need:
 * One slice of bread.
 * A knife
 * Either an oven, grill, braai coals (something that gives off high heat)

Cut the slice of bread into two.

Experiment 1
1. Place one piece on a window sill. (Make sure it is in a spot where it will get a lot of sun).

2. Remove it after two days and check what it looks, and feels like.

Experiment 2
1. Place the other piece of bread in the oven, on or under the grill (depending on which type you have), or over the braai coals.

2. Remove it after a few minutes. (The time will depend on how hot the heat source is). Check what it feels like and looks like.

Write down what has happened to the bread in each experiment.

Answer these questions: (some of these words will help you: dry, evaporate, moisture, water)

1. What do you think happened to the bread?

2. How would you explain this method of preservation to anyone?

3. Name three other materials that this method of preservation could be used on.

4. Write down a method that could be used to preserve a flower.

Some information: Drying is process of removing water (moisture) from a material. In drying the moisture that comes out is not used, i.e. it goes up into the air. One way to remove moisture is by applying heat.

Authors: Nonqaba Williams & Nokwezi Mgudlwa Graphics: Osman Sadeck Editor: Osman Sadeck