Proteolytic and milk clotting activities in extracts obtained from the crustaceans Munida

In the present study, individuals of the crustaceans Munida have been investigated as a possible source of enzymes to be used in cheese making as an alternative to calf rennet. The crustaceans were blended and the extracts were filtered and tested for their proteolytic activity and milk clotting capability. The optimal values of pH and temperature of the total proteolytic activity determined on azocasein were in the ranges pH 6.5–7.5 and 55–60 ◦C, respectively. The extracts showed a higher capability to cleave S1-casein than - and k-casein. As determined with specific inhibitors, using azocasein or zymography, the extracts appeared to contain serine proteases as well as cysteine and aspartic proteases. Hydrolysis of -casein gave peptides which were different from those obtained with trypsin or a commercial calf rennet. Moderate milk clotting activity was also present. The ability to cleave casein, in particular S1-casein, and the moderate clotting activity, indicate that the extracts of the crustaceans Munida could be useful in the dairy industry both for milk clotting, as an alternative or in addition to calf rennet, and for the acceleration of cheese ripening in order to reduce time and costs of storage and maturation of cheese.