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Lesson objective

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.

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Lesson objective

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

  2. 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

  3. 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

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

  5. 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.

  6. 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.

  7. Oxidation of foods

  8. 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

  9. 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

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