Lesson objective LO - To develop an understanding of the effects of storages time, temperature and exposure to sunlight on the nutrient content of food

Question What are the causes of nutrient loss in food? Do you know what the following mean? Oxidation Rancidity Water loss Enzymes LO - To develop an understanding of the effects of storage time, temperature and exposure to sunlight on the nutrient content of food

Task 1 Go onto the internet and find out what oxidation means, how soon do fruit and vegetables start to loose nutrients? Fats and oils can develop an unpleasant smell during prolonged storage. This is know as rancidity and is caused by oxidation What do commercially prepared foods often have added to prevent this from happening? LO - To develop an understanding of the effects of storage time, temperature and exposure to sunlight on the nutrient content of food

Task 2 – draw the table Food acidity and micro-organisms

Acidity or alkalinity Acidity or alkalinity of food is important for two reasons: it affects the taste of a product and it affects the rate at which microorganisms grow within and upon food. For example, lemon juice can be used to reduce the pH level of yoghurt, to a pH below 4.5. This inhibits the growth of microorganisms, making the yoghurt last longer, but it will also give it a sharp taste.

Oxidation of foods Food can also be affected by the oxygen in air. When some fresh fruit, such as an apple or pear, is cut or peeled, the outside surfaces darken and turn brown, making the food seem unattractive. The browning is caused by enzymes in the fruit reacting to the oxygen in the air. By adding an acid (eg lemon juice) or sugary solution (eg syrup), the enzymic browning or discolouring action is slowed down.

Oxidation of foods

Water loss Fruit and vegetables begin to lose moisture during storage and dry out, with a loss of the water soluble vitamins B and C LO - To develop an understanding of the effects of storage time, temperature and exposure to sunlight on the nutrient content of food

Task 2 Now write up some guidelines for preventing nutrient loss Think about Storage Preparation Cooking Buying LO - To develop an understanding of the effects of storage time, temperature and exposure to sunlight on the nutrient content of food