Abstract: The dynamic changes of biogenic amines in yak milk hard cheese with different salt content (1.0%, 1.3%, 1.8% and 2.3%) over a six-month ripening period were analyzed, and amine-producing microorganisms were selected. The results showed that the biogenic amines in yak milk hard cheese with different salt levels were mainly tryptamine, β-phenethylamine, cadaverine, tyramine and putrescine, but histamine was not detected, and the biogenic amines were mainly accumulated in the late stage of maturation. Tryptamine was the least abundant biogenic amine in all the cheeses, and there was little difference in tryptamine content between them in the late ripening stage. When the salt content was reduced from 2.3% to 1.0%, the β-phenethylamine content in the cheese decreased. The content of cadaverine in the cheeses with 1.0% and 1.3% salt content was lower, and putrescine was not detected. As the salt content increased from 1.8% to 2.3%, the content of cadaverine and putrescine in the cheese showed an increasing trend. The tyramine content was 3.13–49.81 mg/kg in the cheeses, and higher at a salt level of 1.3%. The total amount of biogenic amines in the cheeses with different salt levels was up to 304.18 mg/kg. An amine-producing microorganism was selected using a chromogenic medium and identified as Enterococcus durans by molecular biology techniques.

Key words: amount of salt added; yak milk; hard cheese; biogenic amines