1. Mandatory experiments on Food

2. Test for reducing sugar

5. Test for fats

9. Test for protein

12. Test for starch

16. Food Tests – Summary Chart
Test for
Materials
Method
Positive Results
Starch
Iodine Solution
Add iodine to the food sample
A blue/black colour
Reducing sugar (Glucose)
Benedict's Solution
Add to sample and warm gently
A brick red colour
Protein
Copper sulphate (CuSO4) and sodium hydroxide (NaOH)
Biuret solution
Add some NaOH to the moist food. Then gently pour CuSO4 solution down the side of the tube
A violet colour
Fat
Brown Paper
Rub the food onto the paper, warm gently to dry and hold the paper up to the light
A translucent spot
Vitamin C
DCPIP
Add to moist food or fruit juice
A change from blue to pink or colourless

17. Experiment Questions
Food Tests

18. Food Tests
For what is the Biuret test (copper sulphate and sodium hydroxide solutions) used in the biology laboratory? Test for protein

19. Food Tests
For what is the Benedict’s (or Fehling’s) test used in the biology laboratory? Test for reducing sugar

20. Food Tests
For what purpose did you use brown paper or Sudan III in food testing? To test for Fat / Lipid / Oil

21. Food Tests
What reagent or chemicals did you use to test for protein? Biuret OR NaOH and CuSO4

22. Food Tests
Is heat necessary in the test that you carried out to test for protein? No

23. Food Tests
What colour change indicates the presence of protein? From blue to purple / violet

24. Food Tests
Name the test or name the chemical used to test a solution for the presence of glucose (reducing sugar). Clinistix / Benedicts / Fehling’s / Copper sulphate

25. Food Tests
What colour change indicates a positive result for the presence of glucose? (Clinistix) Orange to Blue or (others) Blue to Red

26. Food Tests
Is heat necessary to test a solution for the presence of reducing sugar? Yes

27. Food Tests
For which purpose did you use Biuret solution or alkaline copper sulphate in food testing? To test for (soluble) protein

28. Food Tests
State a use for the Biuret test in the biology laboratory. To detect presence of protein

29. Food Tests
What is the initial colour of the reagent or chemicals used to test for protein? Blue

30. Food Tests
Was there a colour change in the control experiment when testing for protein? No

31. Food Tests
Name the test or give the chemicals used to test a sports drink for the presence of protein. Biuret Test / Sodium Hydroxide & Copper sulphate

32. Food Tests
If protein is present in a drink, what colour change would you expect to see? In your answer give the initial and final colour of the test solution. Blue to violet /purple / lilac

33. Is heat necessary for the test for protein? No
Food Tests
Is heat necessary for the test for protein? No

34. Food Tests
For what purpose did you use Fehling’s solution or Benedict’s solution in the course of your practical activities? To check for Glucose / reducing sugar

35. Food Tests
For which purpose did you use Brown paper or Sudan III in food testing? To test for fat (or lipid or oil)

36. Food Tests—Reducing sugar
(i) Name the reagent(s) used. (ii) State the initial colour of the reagent. (i) Benedict’s/ Fehlings I and II, (ii) Blue

37. Food Tests—Reducing sugar
State whether the test requires heat. Yes

38. Food Tests—Reducing sugar
What colour indicates a positive result? Brick-red/orange

39. Food Tests—Protein
(i) Name the reagent(s) used. (ii) State the initial colour of the reagent. (i) Biuret solution / CuSO4 + NaOH (ii) Blue/ light blue

40. State whether the test requires heat. No
Food Tests—Protein
State whether the test requires heat. No

41. What colour indicates a positive result? Purple / violet
Food Tests—Protein
What colour indicates a positive result? Purple / violet

42. Food Tests
(i) Name a test to show the presence of a reducing sugar (e.g. glucose). (ii) Describe how you would carry out this test. (i) Benedict’s/ Fehling’s (ii) Dissolve sample in water or put in test tube / add reagent / heat / don’t boil / observe change or state result (brick-red-orange precipitate)

43. Food Tests
(i) Name a test for protein. (ii) Describe how you would carry out this test. (i) Biuret test or named chemicals (ii) Add biuret reagent (or sodium hydroxide and copper sulfate) / to sample / heat or shake / observe or record colour change (purple-violet)

44. Questions pg 13/14