Comparing Proteolytic Action of Milk-Clotting Enzymes on Caseins and Cheese

Abstract

The proteolytic properties of fungal rennets from Endothia parasitica and from Mucor pusillus var. Lindt were compared with those of veal rennet and of pepsin. Enzyme proteolysis of whole, αs-, and β-casein, soluble in 12% trichloroacetic acid and soluble nitrogen compounds produced by enzymes on freshly ground mild cheese curd were determined. Residual fractions from the action of the enzymes on the casein substrates and on cheese were determined by polyacrylamide-gel electrophoresis.Fungal rennets showed greater proteolytic activity than did veal rennet or pepsin on whole, αs-, and β-casein. Of the two fungal rennets, the one from E. parasitica was more proteolytic on the casein preparations. There was no significant increase in nonprotein nitrogen by veal rennets or pepsin on β-casein or by veal rennets on αs-casein. When fresh mild cheese was used as substrate, the two fungal rennets produced more soluble nitrogen than did the veal rennets or pepsin.Electrophoretic patterns showed considerable differences among the enzymes with respect to degradation of the specific milk proteins.