food practical

• Why is it important to wear safety goggles during the chemical tests?

  Because all of the chemicals used in these tests are potentially hazardous
• What are the key things to learn for the chemical tests of food groups?

  • Chemicals used to test for each food group
  • Positive results for each test
• What is the first step in preparing a food sample for testing?

  Grind the food sample with some distilled water using a mortar and pestle
• What is done after grinding the food sample with distilled water?

  The paste is transferred to a beaker and more distilled water is added
• What is the purpose of filtering the solution after preparing the food sample?

  To remove suspended food particles
• What do carbohydrates include?

  Starch and sugars such as glucose
• How do you test for starch in a food sample?

  Add a few drops of iodine solution to 2 cm³ of the food solution
• What color change indicates the presence of starch when using iodine solution?

  The iodine solution turns blue-black
• What does it mean if the iodine solution stays orange during the starch test?

  It indicates that no starch is present
• How do you test for sugars such as glucose?

  Add 10 drops of Benedict solution to 2 cm³ of the food solution and heat it
• What does the color change of the Benedict solution indicate?

  It indicates the amount of sugar present
• What color indicates a small amount of sugar in the Benedict test?

  Green
• What color indicates a lot of sugar in the Benedict test?

  Brick red
• What are reducing sugars?

  They are sugars that can be tested using the Benedict test, such as glucose
• What is the test for proteins?

  Add 2 cm³ of Biuret solution to 2 cm³ of the food solution
• What color change indicates the presence of protein in the Biuret test?

  The Biuret solution changes from blue to purple or lilac
• How do you test for lipids?

  Add a few drops of distilled water and ethanol to the food solution and shake gently
• Why do we not filter the solution when testing for lipids?

  Because lipid molecules can stick to filter paper
• What indicates the presence of lipids when testing?

  A white cloudy emulsion forms
• Why is it important to avoid naked flames when testing for lipids?

  Because ethanol is highly flammable
• What are the main food groups tested in the practical?

  • Carbohydrates
  • Proteins
  • Lipids
• What are the steps involved in testing for carbohydrates?

  1. Prepare food sample with distilled water
  2. Test for starch using iodine solution
  3. Test for sugars using Benedict solution
• What are the steps involved in testing for proteins?

  1. Prepare food sample
  2. Add Biuret solution
  3. Observe color change
• What are the steps involved in testing for lipids?

  1. Prepare food sample
  2. Add distilled water and ethanol
  3. Observe for white cloudy emulsion