If HCl is not secreted in the stomach, then pepsin wouldn't be activated. This would affect protein digestion. A pH of about 1.8 is necessary for proteins to be digested. This pH is achieved by HCl. Hydrochloric acid kills bacteria and other micro-organisms that may be present in food. In addition, an acidic environment is needed for the enzymes in gastric juice (pepsin) to work. It can also cause the infected food to come in our stomach.