Nutrition and food tests

• Food tests


  • Benedict's
  • Biuret
  • Iodine
  • Emulsion
• Benedict's reagent


  Used to test for sugars
• Benedict's test


  • Requires heat
  • Produces a blue—>brick red precipitate for positive result
• Biuret reagent


  Used to test for proteins
• Biuret test


  • Produces a purple/lilac colour for positive result
• Iodine


  Used to test for starch
• Iodine test


  • Produces a yellow- brown —>blue/black colour for positive result
• Emulsion test


  Used to test for fats
• Emulsion test


  • Produces a white emulsion for positive result
• Carbohydrates are a source of energy
• Sugars are a type of carbohydrate that can be used as an energy reserve
• Benedict's is the only test that requires heat
• Investigating the energy content of food by burning food samples


  1. Use a calorimeter to measure the heat energy

  2. Burn the food sample

  3. Measure the gas produced

  4. Weigh the remaining food
• Proteins are long chains of amino acids
• Proteins can be structural or functional
• Good sources of protein include lentils, fish, and lean meat
• Complex carbohydrates include starch, glycogen, and cellulose
• Fats are made up of fatty acid moieties
• Fats are an excellent source of energy
• Fats can also be used to make structural carbohydrates
• Starch is made up of many glucose molecules
• Glycogen is a storage carbohydrate found in animals
• Cellulose is a structural carbohydrate found in plants