Function of Rennin Enzymes

Enzymes are organic catalysts produced in the body of all living organisms. The human body produces a number of different enzymes. Enzymes carry out or accelerate a number of chemical reactions in the body. They play a significant role in the metabolism and maintain biochemical energy. Enzymes are necessary for regulating many vital body processes like digestion, respiration, blood clotting or coagulation, reproduction as well as the process of growth and development. Rennin is an enzyme belonging to the aspartic proteinases family of enzymes. It is produced in the stomach of young mammals. It is also referred to as chymosin or rennet. This enzyme is essential for the digestion of mother's milk in young mammals.

Function of Rennin Enzymes

Rennin is a coagulating enzyme produced in the inner lining of the abomasum (the fourth/true stomach) of the milk-fed calf. It is also produced in the stomach of a goat or lamb. Some alternative sources of chymosin are plants, especially thistles and nettles and microbes like fungi and yeasts. Being a proteolytic enzyme, major function of rennin is to curdle milk. Rennin enzymes are produced in abundant amount immediately after the birth. Its production gradually decreases and is replaced by the digestive enzyme, called pepsin.

Rennet is known to play an important role in coagulation and curdling of milk. Milk is separated into liquid or whey and semi-solid or curd. Curdling of milk is essential for the proper digestion of milk proteins in the stomach. If milk is removed immediately from the stomach in its undigested state, then young mammals won't benefit from the milk proteins. Coagulation of milk by rennet allows it to remain for a longer time in the stomach.

How does rennin cause curdling of milk? Rennin is produced in the form of inactive prorennin. After consumption of milk, the hydrochloric acid in the gastric juice present in the stomach activates prorennin and converts it into its active form, rennin. There is a caseinogen enzyme present in the milk, which has four types of molecules. Rennin precipitates three of them, namely alpha-s1 and alpha-s2 casein and beta casein, in the presence of calcium in the milk. The fourth molecule in the caseinogen enzyme, called kappa casein is not precipitated by calcium. Kappa casein is known to prevent the precipitation of alpha and beta caseins. Since coagulation is necessary, rennin enzymes inactivate kappa casein. In this way, milk is coagulated and properly digested, so that young mammals get all its advantages.

The most optimum temperature required for the reaction of milk and rennin is 37 degree Celsius. At higher temperatures, the rennin enzyme molecules break down and the action of rennin on milk ceases. If the temperature falls, it slows down the rate of reaction.

Industrial Application of Rennet

Due to its coagulating action on milk, rennin enzyme is commonly applied in the food industry. It is widely used for the production of cheese. Rennin required for the cheese production was obtained mainly from the calf stomach as well as from other non-animal sources. But, for the industrial cheese production, a large amount of rennin is required. Therefore, genetic engineering methods are used nowadays in order to obtain greater amounts of rennin enzymes.