Advances in the study of proteolysis during cheese ripening

Cheese ripening involves a complex series of biochemical, and probably some chemical events, that leads to the characteristic taste, aroma and texture of each cheese variety. The most complex of these biochemical events, proteolysis, is caused by agents from a number of sources: residual coagulant (usually chymosin), indigenous milk enzymes, starter, adventitious non-starter microflora and, in many varieties, enzymes from secondary flora (e.g., from Penicillium sp. in mould-ripened cheeses or Propionibacterium sp. in Swiss cheese). Proteolysis in cheese has been the subject of active research in the last decade; there have been developments in the analytical techniques used to monitor proteolysis and patterns of proteolysis in many cheese varieties have now been investigated. This review focuses on certain aspects of proteolysis, including proteolytic agents in cheese and specificity of some ripening enzymes, comparison of proteolysis and contribution of proteolysis to cheese flavour.