Effect of ripening time on proteolysis, free amino acids, bioactive amines and texture profile of Gorgonzola-type cheese

The effect of ripening time on Gorgonzola-type cheeses at 12 ± 2 °C was investigated. Proteolysis indexes, free amino acids and bioactive amines increased throughout ripening. However, cohesiveness and lactic acid bacteria counts decreased; whereas pH, total protein, total mesophilic aerobic bacteria counts, and other instrumental texture parameters did not change. Valine, lysine, leucine and phenylalanine were the most abundant free amino acids throughout ripening. Glycine, histidine and isoleucine were first detected on the 21st day and aspartic acid and glutamine on the 28th after perforation. The levels of most amino acids increased, except serine that decreased and tyrosine remained constant. Among amines formed during ripening, tyramine and agmatine were first detected on the 21st day, serotonin on the 42nd and histamine and tryptamine on the 49th. On the 21st day, tyramine reached contents which could be of health concern for individuals taking classical monoamine oxidase inhibitor drugs. Principal Component Analysis and Hierarchical Cluster Analysis showed that proteolysis (extend and depth indexes) and free amino acid profile are suitable markers for ripening assessment of Gorgonzola-type cheese. They were also able to assess cheese characteristics, quality and safety.