Question

When a food sample is treated with iodine solution, a blue-black colour or precipitate is obtained. What does it indicate?

• A. Presence of proteins
• B. Presence of starch
• C. Presence of fats
• D. Presence of vitamins

Answer 1

The correct option is B

Presence of starch

Explanation for the correct option:
(B) Presence of starch

• Iodine test is used to determine the presence of starch in food items.
• If iodine is added to starch it causes the starch to turn to a blue-black colour. This indicates the presence of starch.

Explanation for the incorrect options:
(A) Presence of proteins

• If iodine is added to proteins no change in the colour is observed.

(C) Presence of fats

• If iodine is added to fats no change in the colour is observed.

(D) Presence of vitamins

• If iodine is added to vitamins no change in the colour is observed.

Hence, option (B) is correct., In presence of starch food items turn into a blue-black colour.