Biochemical properties of commercial recombinant chymosin preparations

This study investigates the biochemical properties of commercial recombinant chymosin samples available on the Russian market. One of the most critical steps in the production of natural cheese is the coagulation of milk into a curd under the action of rennet or other milk-clotting enzymes. While milk coagulation can be induced by various proteases capable of hydrolyzing κ-casein, the quality of the final product significantly depends on the biochemical properties of the enzyme. These properties influence the proteolytic processes occurring in the cheese from production to maturation. In this work, we examined the effects of hydrogen ions, calcium, and temperature on the specific (milk-clotting) activity of the enzyme preparations. The activity was determined in accordance with the industry standard OST 10288-2001 (“Milk-Clotting Enzyme Preparations”). The non-specific (proteolytic) activity was measured using a standard method of E.D. Kaverzneva, adapted for laboratory studies of milk-clotting enzymes. The results demonstrated that the biochemical properties of the tested commercial recombinant chymosin samples were equivalent to those of the industry reference standard for rennet. This finding supports their suitability for producing cheeses with a high second heating temperature, for which the conventional technology uses rennet. In Russia, the production of genetically engineered chymosins is not currently undertaken. Consequently, the development of domestic production technologies for recombinant chymosin remains highly relevant. Such studies are being conducted by the Siberian Research Institute of Cheese Making in collaboration with the State Research Center of Virology and Biotechnology “Vector” (Rospotrebnadzor).

milk-clotting enzymes, recombinant chymosin, cheese, coagulation, milk-clotting activity, proteolytic activity, thermostability, temperature optimum