Lesson objective

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Lesson objective

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

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

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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.

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Oxidation of foods
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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
10
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