Chymosin and other milk coagulants: sources and biotechnological interventions

Abstract

Calf rennet, which consists of over 90% chymosin, is commonly used in cheese industries for the curdling of milk. Various animal, plant and microbial sources have been exploited as possible alternatives to calf rennet. The coagulating properties of the enzymatic preparations (coagulants) from these sources differ in terms of their physicochemical factors. The cheese industry has always sought out novel and stable enzyme sources, and recombinant chymosin has been found to be an effective alternative since it possesses several advantages over plant and microbial milk-clotting enzymes. This paper reviews the use of various milk coagulants, especially animal coagulants, for cheese making. Advancements in genetic and protein engineering to produce recombinant chymosin are discussed in addition to evaluating its identity to the rennet available from natural sources.

Keywords::

• Rennet
• recombinant chymosin
• milk-clotting
• genetic engineering
• protein engineering
• cheese preparation

Acknowledgements

The authors acknowledge The Director, NDRI, Karnal, for providing necessary facilities and infrastructure, and Department of Biotechnology (Govt. of India), New Delhi, for research fellowship. The authors also wish to thank Dr. Ravinder Nagpal, JMIT, India, and Mr. Vijay Kumar, JP Morgan, Sydney, for critically improving the manuscript quality.

Declaration of interest

The authors report no conflicts of interest.