Need for processing food

• Food is processed to:
  • make it edible (preparing, cooking);
  • make it last longer (preserving);
  • improve its nutrient value (fermenting).
• During processing many foods may lose some of their nutrients.

• Greet the learners.
• Ask learners:
  • Where do you keep your milk and cheese at home?
  • Why is some food stored in a fridge and some food stored in a cupboard? Give reasons for your answers.
  • How do you think people from long time ago, before fridges or freezers were invented, kept their food fresh and safe to eat?

Answer:  People used salt, vinegar and spices to make meat last longer (to preserve it) and then they hung it out to dry.  Biltong is an example of dried or cured meat.  When we cure fish, we get bokkoms.

• Explorers from hundreds of years ago – Vasco da Gama, Christopher Columbus and Bartholomew Diaz had to take a lot of food and water supplies on their ships when they went on long sea journeys. This food and water had to last for a long time, since they would not reach land for many months after setting sail.
• The sailors had a diet consisting of: salted or pickled fish and meats (beef and pork), salted flour, lentils, chickpeas, beans, rice, sea biscuits, honey, raisins, cheese and liquids (water, vinegar, wine and olive oil).
• Explain that the foods that da Gama, Columbus and Diaz took on their sea journeys are examples of processed food.
• Write the names of the following foods on your blackboard.
  • biltong
  • pickled onions
  • pilchards in a tin
  • baked beans
  • hamburger patties
  • polony or ham
  • dried fruit
  • cheese spread
  • yogurt
  • peanut butter
  • amasi
  • popcorn
  • samp
  • rice
  • bread

• Ask learners:
  • To indicate which of the listed foods they like eating and to give a reason why they like / do not like these foods.
  • What do all these foods have in common?

Answer:  All these food have been processed in one way or another.

• Ask learners: Why is food processed?

Help the learners to identify three reasons:

1. Food is processed to make it last longer.

Examples of this kind of food are: biltong, dried fruit, pickled onions, tin food (like pilchards and baked beans).

2. Food is processed to make it edible.

Examples of this kind of food are: popcorn, rice and samp.

3. Food is processed to improve its nutrient value.

Example of this kind of food is peanut butter, yogurt, amasi, cheese and bread.

Explain that when we ferment milk to make yogurt, buttermilk and cheese, this form of processing ads to the nutritional value of the products, for example, yoghurt contains bacteria that is good for us.

• Learners complete WORKSHEET A: Reasons for processing food.
• Guide the learners on how to undertake this activity by providing examples and explaining how this worksheet will be assessed.

• Explain to the learners that we have discovered the reasons why food has to be processed.
• Can they remember these reasons?
• To preserve it (make it last longer);
• To make it edible;
• To add to the nutritional value of the food.

• Have a few slices of fresh bread available for this investigation as well as a selection of containers.
• Before the lesson, ask the learners to assist by bringing containers or wrappers from home.
• Tell the learners that they are going to do an investigation to see which type of container or wrapping will keep bread fresh for longer.
• Divide the class into smaller groups.
• Each group must:
• cut the bread into equally sized portions;
• sprinkle a few drops of water on each slice of bread;
• place each slice of bread into a different plastic bag and seal these bags as tightly as possible;
• write the name of their group on each of their plastic bags;
• place one plastic bag into a dark place (e.g. a cupboard);
• place one plastic bag in a cool place (e.g. a fridge or storeroom);
• place one plastic bag in the sunlight;
• leave the plastic bags in place for five days.
• Learners complete WORKSHEET B: Scientific Investigation into Food Preservation and record their findings over the five days.

Guide learners on how to undertake this scientific investigation and explain how this worksheet will be assessed.