Question

Can humans digest casein?

Answer 1

Casein is digested by an enzyme that breaks down the proteins into smaller peptides. So, it is an endopeptidase. This enzyme in its inactive form is called zymogen and found in the small intestine. It helps in the digestion of dairy products, means, or eggs.

Complete answer:
In humans, it is hard to digest casein as the digestive enzymes for its breakdown present in the small intestine are very few in number. There are various enzymes that are used for the digestion of the milk protein casein. One of the most important digestive enzymes present in gastric juices of the chief cells of the small intestine is pepsin. It is found in humans along with various other animals. Pepsin helps in digesting the proteins present in the food along with the dairy products. While in the case of ruminant animals rennin is found for the digestion of the milk protein. It is found in a very small quantity in the case of humans but only at the infant stage and is found to be absent during adulthood.
The Chymotrypsin enzyme is changed over the activity of trypsin in the digestive system into dynamic chymotrypsin. Chymotrypsin is an enzyme that helps in the coagulation of milk thus resulting in the hydrolysis of casein and gelatin, it is secreted by the pancreatic juice. Rennin is the enzyme that is known to coagulate the milk and it is also used for making cheese. Rennin is the milk digesting enzyme mostly present in the infants of cows and is absent in the case of humans. This enzyme helps in the curdling of the milk as it is a protein-digesting enzyme resulting in the milk protein transforming into casein. It is observed to be located in the ruminant animals’ fourth stomach. This enzyme extends the period of milk absorption by retaining the milk in the stomach. It is widely used in the production of cheese in the cheese-producing industries by thickening the milk. Renin is considered to be a thickening agent and is used in the formation of the curds from the milk. It is a source of milk digestion in the case of young ruminant animals and found in their fourth stomach.

Note:
Casein in the cow is the major component of protein and is important for its nutritional value. It is responsible for the appearance of the characteristic of the milk as it gives the look of the colloidal solution and forms large micelles of it. It is a globular protein that hardens when and becomes insoluble proteins and thus is hard to digest.