The Hydrochloric Acid breaks down the food, and the digestive enzymes split up the proteins in the food. The acid also kills bacteria. Some of the glands produce a thick, protective layer of mucus that prevents the acid from attacking the wall of the stomach.
Hydrochloric acid is an inorganic chemical. It is a strong corrosive acid with a chemical formula HCl. It is also known as hydrogen chloride or muriatic acid. When hydrogen chloride is dissolved in water HCl is formed.