Why pickles and curd are not stored in Copper and Brass utensils?

Sour substances like curd and pickles should not be kept in brass and copper utensils as the sour substances are acidic in nature and react with the metallic surface of the brass and copper to form some poisonous or toxic compound which may be harmful to the human body.

Therefore, pickles and curd should not be stored in copper and brass utensils.