Abstract: The volatile flavor components in Beijing spiced beef during 4 different cooking times were extracted and identified by purge and trap thermal desorption (P&T-TD) combined with gas chromatography-mass spectrometry (GC-MS) in an effort to determine the optimal cooking time to achieve the best flavor. A total of 93 volatile compounds were identified in Beijing spiced beef during cooking for 1, 2, 3 and 4 h. The numbers of volatile compounds identified at 4 cooking times were 60, 60, 69 and 60, respectively, and 36 compounds were common to four samples. Ketones and esters reached a peak at 1 h, alcohols, phenols and heterocyclic compounds reached a peak at 2 h, hydrocarbons exhibited the highest value at 3 h, and aldehydes and ethers reached the highest value at 4 h. At the same time, the composition of volatile flavor compounds in the samples was analyzed with e principal component analysis and comprehensive factor scores. The results showed that the 2 h-cook sample gained the highest comprehensive score. In term of volatile flavor analysis, Beijing spiced beef had better flavor in two-hour cooking.

Key words: Beijing spiced beef, purge and trap thermal desorption (P&T-TD), gas chromatography-mass spectrometry (GC-MS), volatile flavor components, principal component analysis (PCA)