Biochemistry of cheese ripening

Abstract

Cheese ripening basically includes the breakdown of proteins, lipids and carbohydrates which releases flavour compounds and modifies cheese texture. Principal ripening agents are milk enzymes (plasmin and lipoprotein lipase), milk coagulant, starter lactic culture, secondary culture and ripening agents. The ripening process of cheese is very complex and involves microbiological and biochemical changes to the curd resulting in the flavour and texture characteristics of the particular variety. Microbiological changes during ripening include the death and lysis of starter cells, nonstarter lactic acid bacteria, and secondary microflora in many varieties of cheese. Moulds in mould-ripened varieties and a complex Gram-positive bacterial flora in smear cheeses are of great importance to the flavour and texture of cheese. Cheese texture softens during ripening as a consequence of proteolysis of the casein micelle and changes to the water-binding ability of the curd and in pH. The biochemical changes occurring during ripening may be grouped into primary events that include the metabolism of residual lactose, lactate and citrate (glycolysis), lipolysis and proteolysis. Following the primary events, secondary biochemical events occur which are responsible for the development of many volatile flavour compounds of ripened cheese varieties.