Aged, Dried, and Hard Cheeses

The aging of cheeses is a complex process that involves a whole range of biochemical and physical changes. Enzymes from the rennet, lactic acid bacteria, and other microorganisms all come into the picture. They break down the milk protein casein into small peptides and free amino acids, especially leucine, valine, lysine, phenylalanine, and glutamic acid (glutamate). It is the taste of these amino acids that we identify with that of aged cheese. Because the microorganisms also need amino acids for their own growth during this period, the timeline for the free amino acid content of, for example, glutamate becomes very complicated, and it can peak and then start to decline.