Food Tests

Question 1

How do you test for starch?

Answer 1

-Take a food sample and place on a spotting tile
-Add a few drops of iodine SOLUTION
-If starch is present, the iodine changes colour from orange to black/blue

Question 2

How do you test for Glucose (and other reducing sugars)?

Answer 2

• Place a small sample in test tube
  -Add Benedict’s solution, or enough for the mixture to appear blue
  -Heat in a water bath (85°C) for 5 mins
  -If mixture changes from blue to green / yellow / orange / red, then glucose ( or another reducing sugar) is present in that food

Question 3

How do you test for protein?

Answer 3

-Place a sample in a test tube
-Add enough Biuret solution to allow the colour to be seen (pale blue)
-If the mixture turns mauve / purple, protein is present in the food

Question 4

How do you test for fats?

Answer 4

-Place a small sample in a test tube
-Add ethanol and mix well
- Add water and shake again
-If the mixture turns a milky colour, then fat is present in the food