Question

Why should curd and other sour foodstuffs (like lemon juice, etc.) not be kept in metal containers (such as copper and brass vessels)?

Answer 1

Curd and sour foodstuffs contain acids. These acids react with metals such as copper and brass to form poisonous metal salts. The food gets contaminated and may become harmful to health. Therefore, such foodstuffs should not be stored in metal containers.