Food Tests - Starch And Sugars

Question 1

Explain the process for test for starch

Answer 1

1. Test solution in test tube
2. Iodine in potassium iodide solution
3. Gently mix by swirling

Question 2

What is the positive result for the starch test?

Answer 2

Browny orange to blue-black

Question 3

Explain the test for reducing sugars

Answer 3

1. Test solution in boiling tube
2. Equal volume of Benedict’s reagent
3. Heat for 5 mins

Question 4

What is the positive result for reducing sugars?

Answer 4

Blue to orangey red

Question 5

Explain the test for non reducing sugars

Answer 5

1. Test solution in boiling tube
2. Equal volume of Benedict’s reagent
3. Heat mixture
4. Record colour - not a reducing sugar if remains blue
5. Test solution in boiling tube
6. Add hydrochloric acid
7. Heat
8. Sodium hydroxide to neutralise
9. Add Benedict’s reagent
10. Heat for 5 mins

Question 6

What is the positive result for non reducing sugar test?

Answer 6

Blue to orangey red