MacroNutrients

• Nutrients


  Chemical substances such as carbohydrates, lipids and proteins that are the basic building blocks of all living organisms
• Organic compounds


  Food substances that are required in large amounts in a balanced diet
• Organic compounds


  • Carbohydrates
  • Lipids
  • Proteins
• Carbohydrates


  • Contain carbon, hydrogen and oxygen only
  • Provide energy for all living organisms
• Types of carbohydrates


  • Monosaccharides (one sugar molecule)
  • Disaccharides (two sugar molecules joined together)
  • Polysaccharides (more than two sugar molecules)
• Monosaccharides


  • Glucose
  • Fructose
• Polysaccharides


  • Starch
  • Cellulose
  • Glycogen
• Carbohydrates


  Major energy source
• Lipids


  • Secondary energy source
  • Provide insulation
  • Part of the cell membrane
• Lipids


  Composed of glycerol and fatty acids
• Condensation


  Removal of water molecule when two monosaccharides are joined
• Hydrolysis

  Addition of water molecules to split the monosaccharides
• Proteins


  • Composed of carbon, hydrogen, oxygen and nitrogen to form amino acids
  • Functions include growth, repair, enzymes, hormones, transport, protection
• Proteins


  Made up of long chains of amino acids, there are 20 different amino acids
• Proteins


  • Have more carbon, hydrogen and oxygen atoms than carbohydrates and lipids
• Rich food sources of proteins

  • Meat, fish, eggs, dairy
• Maltose


  Glucose + glucose
• Sucrose


  Glucose + fructose
• Starch


  Stored in food
• Cellulose


  • Fibres in the plant cell
• Glycogen


  Stored in animal cells
• Test for lipids


  Add ethanol, then pour mixture into water in another test tube
• Results


  White cloudy emulsion forms in water
• Test for Protein


  Add Biuret Solution
• Results


  Pale blue -> violet/purple colour
• Food substances


  • Testing for Simple Sugars (Reducing Sugars)
  • Testing for complex Sugars (Non-reducing Sugars)
  • Test for Starch
• Testing for Simple Sugars (Reducing Sugars)

  Add Benedict's solution, heat to 80°C
• Results


  Blue to orange-red colour change
• Testing for complex Sugars (Non-reducing Sugars)

  If negative for reducing sugar test, boil with hydrochloric acid (HCl), cool and neutralise with sodium carbonate solution. Repeat Benedict's test.
• Complex Sugars

  Initially no change, repeat Benedict's test will turn blue to orange-red
• Test for Starch


  Add a few drops of iodine Solution
• Starch

  Orange to blue-black colour change