Food test practicals

• What is the purpose of the Benedict's test?

  To test for reducing sugars
• What does the iodine test detect?

  It detects starch in food samples
• What does the buret test check for?

  It checks for proteins in food samples
• What is the Ethanol test used for?

  To test for lipids in food samples
• What is the emulsion test for lipids?

  A test for lipids using ethanol and water
• What should you do after crushing the food sample?

  Add it to distilled water and stir
• How do you filter the food sample solution?

  Use a funnel lined with filter paper
• What are the two types of sugars?

  Reducing sugars and non-reducing sugars
• What does a blue solution indicate in the Benedict's test?

  No reducing sugars are present
• What color change indicates the presence of reducing sugars?

  Changes to green, yellow, or brick red
• What color does iodine turn in the presence of starch?

  Changes from brownish-orange to blue-black
• How much sample is needed for the buret test?

  Two centimeters cubed of the sample
• What color change indicates the presence of proteins in the buret test?

  Changes from blue to pink or purple
• What indicates the presence of lipids in the Ethanol test?

  A bright red layer at the top
• What is the procedure for the ethanol test?

  Add ethanol, shake, then add water
• What does a cloudy white color indicate in the emulsion test?

  Presence of lipids in the sample
• What are the steps to prepare a food sample for testing?

  1. Break food using a mortar and pestle
  2. Add crushed food to distilled water
  3. Stir until dissolved
  4. Filter using a funnel and filter paper
• What are the key differences between the tests for sugars, starch, proteins, and lipids?

  • Benedict's test: for reducing sugars
  • Iodine test: for starch
  • Biuret test: for proteins
  • Ethanol test: for lipids
• What are the safety precautions for the Benedict's test?

  • Use a test tube holder
  • Point the tube away from yourself
  • Handle hot equipment carefully
• What are the expected results for each food test?

  • Benedict's: blue (no sugar), green/yellow/brick red (sugar present)
  • Iodine: brownish-orange (no starch), blue-black (starch present)
  • Buret: blue (no protein), pink/purple (protein present)
  • Ethanol: no red layer (no lipid), bright red layer (lipid present)
  • Emulsion: clear (no lipid), cloudy white (lipid present)
• What are the differences between reducing and non-reducing sugars?

  • Reducing sugars: can donate electrons
  • Non-reducing sugars: cannot donate electrons
• What is the significance of using distilled water in food tests?

  • Prevents contamination
  • Ensures accurate test results