Chymosin: from the traditional role to a new paradigm on cheese proteolysis?

Abstract

The aspartic proteinase chymosin (EC 3.4.23.4) is the principal milk-clotting enzyme used in cheese manufacture and one of the main proteolytic agents involved in cheese ripening. This review examines the role of its proteolytic activity in the ripening of both traditional cheeses (soft, semihard and hard) and innovative varieties, including cheeses manufactured from concentrated milk as well as fat- and salt-reduced cheeses, with particular emphasis on the factors affecting its retention in the curd. Finally, the review also addresses the development of novel engineered or modified chymosins with reduced nonspecific proteolytic activity, discussing the rationale behind this technological change aimed at reduced or negligible chymosin-mediated proteolysis during cheese ripening.