8Aa Nutrients

• In science the word diet means what you eat
• Your diet provides raw materials for your body, which are needed for energy, growth, repair and health
• Food substances that provide raw materials are called nutrients. These include:

  • Carbohydrates
  • Proteins
  • Fats
  • Vitamins
  • Minerals
• Two main carbohydrates in food are starch and sugars
• Liquid fats are called oils
• Fats and oils are sometimes called lipids
• Fibre is made of plant cell walls and is not used by the body, but it keeps us healthy by helping food move through the intestines and stopping constipation
• Water :

  • acts as a lubricant
  • fills up cells so they hold their shape
  • dissolves things so that they can be carried around the body
  • cools you down when you sweat
• Food labels must have a list of ingredients and must point out substances that people may be allergic to such as nuts or eggs
• Test for starch:

  • add two drops of iodine solution
  • if there is starch, you will see blue-black colour
• Test for protein:

  • place a food sample in a test tube to a depth of about 1 cm
  • add 5 drops of biuret solution
  • if there is protein you will see a purple color within a few minutes
• Test for fats:

  • rub a small dry food sample on some white paper
  • hold up the paper up to the light
  • fats leave a greasy mark
• Test for vitamin C:

  • add 5ml of the liquid food sample to a test tube containing 2ml of DCPIP solution
  • if the substance turns to a blue-black color, vitamin C is present