Science food test

• Starch test: method: add few drops of iodine solution to the food sample
• Starch test: observation: starch present= turn blue-black

  Starch absent=remains yellowish-brown
• Benedict's test(reducing sugar):

  Method:

  Add 2 cm³ of food sample into test-tube.

  Add 2cm³ of benedict's solution and shake thoroughly.

  Immerse the test-tube in a boiling water bath for 5 mins
• Benedict's test: observation:

  Blue benedict's solution forms a brick-red precipitate(large amount of sugar)

  Orange-yellow(moderate amount)

  Greenish precipitate(traces of reducing sugar)
• Benedict's solution: observation

  Benedict's solution remains blue when reducing sugar is absent
• Test for fats: ethanol emulsion test

  Method:

  Add 2cm³ of alcohol to 2cm³ of food sample in a test tube and shake thoroughly.

  Add 2cm³ of water to the mixture and shake.
• Test for fats: observation

  Colourless solution changes to a white emulsion= fats is present
• Test for fats: solution remains colourless= fat is absent
• Protein: biuret test

  Method: add 2cm³ of Biuret solution to 2 cm³ of food sample in a test tube and shake

  Allow the mixture to stand for 5 minutes.
• Protein: observation

  Blue solution changes to violet= protein is present
• Protein: observation

  Solution remains blue, protein is absent
• Starch test(iodine test): test for starch
• Benedict's test: test for reducing sugar
• Ethanol emulsion test: test for fats
• Biuret test: test for protein