What is Rennet?

Rennet is a complex combination of enzymes produced in the stomachs of ruminant mammals. Chymosin, one of the protease enzymes is the major component of Rennet. Other enzymes  includes pepsin and lipase. In young mammals, this is produced in abundance to digest the mother’s milk. It is used extensively in cheese making for separating the solid curds and liquid whey.

Rennet Production

The traditional way of producing  involves slaughtering of calves or cows and extracting the product from their stomach. However, the yield of the product is too small and inadequate to meet the demand for cheese industry. Nowadays alternative sources of rennet have been identified and exploited for the purpose.

Plants, vegetables and microbes are the other sources  identified, of which microbes have won the race and put into effective use in  production at industrial scale. In order to match the quality of the animal rennet microbes have been incorporated with animal gene producing chymosin into the molds like Aspergillus Niger and Kluyveromyces Lactis by genetic engineering tools. These molds are cultured in large fermenters to harvest chymosin. As the fermentation process is a standard industrial scale-up procedure, it can be optimized to maximum yield and desired parameters of the product. The process produces large quantities of the enzyme which is further processed and purified to prepare ready to use commercial rennet.  This product is popularly known by the term Fermentation Produced Chymosin (FPC). The FPC is far better for cheese production when compared the animal , as it can be produced in large scale, can impart better texture to the curd and reduce the bitterness of the cheese. Two popular international brands of FPCs are CHY-MAX® and MAXIREN®.