In addition to storage and mechanical breakdown of food, the stomach initiates protein digestion and denatures proteins. is the first site where absorption takes place. is the only place where fats are completely digested. is the first site where chemical digestion of starch takes place.

In addition to storage and mechanical breakdown of food, the stomach initiates protein digestion and denatures proteins. It is also the first place where proteins are chemically changed. The gastric juices in the stomach causes the long peptide chains of protein to unfold. The acidity of the gastric juices must have a pH of no more than 3.