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 is an illegal preservative added to milk to increase its shelf life. To detect it, ferric chloride solution and concentrated sulfuric acid are added to the milk sample. The appearance of a violet color at the junction of two layers confirms the presence of formaldehyde. This test is crucial for identifying unsafe milk and preventing its consumption.