WANG Huihui, MA Jibing, LIU Xiaobo, CUI Wenbin, ZHANG Li, WEI Jinmei, YU Qunli, GUO Zhaobin
The yak meat, which is from Gannan area in Gansu province was taken as the research object to study the composition and changing rules of its volatile flavor compounds during natural freeze-drying process. The flavor compounds of air-dried yak meat during process on day 0, 2, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50 and 60 were quantitatively and qualitatively analysed by using headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results showed that a total of 41 kinds of volatile flavour compounds were detected during traditional air-drying process of beef in the pastoral areas of Gansu, including esters (12), acids (6), aldehydes (3), ketones (9), alcohols (3), ether (1), hydrocarbon (1), sulfur-containing compound (4), and heterocyclic compound (2). During the whole air-drying process, the total relative contents of esters, ketones, and alcohols overall showed a decreasing trend. Acids, hydrocarbons, and ethers did not show obvious changes. Aldehydes increased at first and then decreased during the air-drying process. The total relative contents of sulfur compounds showed a significant increasing trend (P<0.05). The results of principal component analysis of these 41 kinds of volatile flavor compounds during the air-drying process of yak meat showed that the first main component mainly came from the Maillard reaction, which mainly included 1,2-ethanedithiol, phenylacetaldehyde, 2,3-hendanedione etc. The second main component mainly came from fat oxidation products, which mainly included α-ketoglutarate, n-hexanol, 3-methylvalerate etc. 0th-15th days was found to be the key stages for flavor formation.