Influence of Coagulant Concentrate on Volatile components of Hard Cheese Made from Yak Milk

In order to investigate in influence of coagulant concentrate on volatile components of hard cheese made from yak milk cheese samples with half normal concentration of rennet(0.5X), normal concentration of rennet(X), 1.5 times normal concentration of rennet(1.5X) and with double concentration of rennet (2X) were analyzed by SPME coupled with GC-MS. Main volatile components in different cheese made from yak milk included acids, alcohols and esters, followed by hydrocarbons. From 0.5X to 2X, number and content of volatile compounds gradually decreased and tended to stabilization. Esters were the first most abundant group of compounds and most of the identified esters were ethyl esters. Alcohols were the second most abundant group of compounds with ethanol which existed in all cheeses and 3-methylbutanol which existed in all cheeses except for 0.5 X cheese. Acids were the third most abundant group of compounds and from 0.5X to 2X, acid species and content decreased. Only three volatile components were the same in the all of cheese and most of compounds are different among the cheese. Therefore, coagulant concentrate influenced on number and content of volatile components of hard cheese made from yak milk.