Both the Curd and sour substances are acids. Acids react with metals to provide salt and hydrogen gas. When sour substances like curd are kept in brass or copper vessels , the carboxylic acid in curd reacts with the metals that results in the corrosion of the vessels moreover as the formation of harmful salts that can’t be consumed. So, if such substances are kept in brass and copper vessels, the acid can react and also the containers are corroded. Thereby could spoil the food.
Final Answer:
When sour substances like curd are kept in brass or copper vessels , the carboxylic acid in curd reacts with the metals that results in the corrosion of the vessels moreover as the formation of harmful salts that can’t be consumed. Thereby could spoil the food.