Abstract:Headspace solid phase microextraction combined with gas chromatography-mass spectrometry was applied for the detection of volatile compounds in Tibetan kefir milks fermented with two Tibetan kefir grains of different geographical origins，and the odor activity values（OAVs）were calculated based on threshold values of compounds.The results showed that a total of thirty volatile compounds were identified，acids and alcohols were dominant in all samples.The ability to produce volatile flavor compounds of the two Tibetan kefir grain varieties was different，the total kinds and content of volatile compounds in kefir milk B were higher than in A.Esters were the most important aroma contributing compounds in the two kinds of kefir milk，ethyl octanoate possessed the most important aroma contribution for all samples.The total aroma contribution of different classes of compounds for the two kinds of kefir milk was different；the total aroma contribution of alcohols was higher for kefir milk A than B，the total aroma contribution of esters，acids and ketones was higher for kefir milk B than A.