Question

How will you detect the presence of formaldehyde in milk?

• A. When adulterated milk is treated with HCl and resorcinol powder and boiled in water, it gives red color.
• B. When adulterated milk is heated, cooled, and added with 1% iodine solution, it becomes blue.
• C. When adulterated milk is treated with para-phenylenediamine hydrochloric acid, it gives dark blue color.
• D. When adulterated milk is treated with ferric chloride solution and concentrated sulfuric acid, violet color develops at the junction of two layers.

Hint:

Learn legal standards for milk safety and avoid using formaldehyde as a preservative.

Answer 1

The Correct Option is D

Formaldehyde, an illegal preservative, is sometimes added to milk to extend its shelf life. Its detection involves adding ferric chloride solution and concentrated sulfuric acid to a milk sample. A violet color appearing at the junction of the two layers confirms its presence. This test is crucial for identifying and preventing the consumption of unsafe milk.