Abstract: The effects of roasting time and methods on the volatile composition of highland barley (cv. Dulihuang) were studied by gas chromatography-mass spectrometry (GC-MS) combined with aroma analysis. The results showed that with the increase of stir-frying time, the types and contents of volatile substances increased, and the main flavor substances were heterocyclic compounds. The highest content of volatile substances of 46.09% was obtained at 8 minutes of stir-frying time. The traditional process of stir-frying followed by grinding produced more types of heterocyclic compounds as well as more prominent characteristic roasted aroma as compared with the opposite sequence. A total of 21 peaks were found to be common to all samples irrespective of stir-frying time or methods, among which pyrazines were the most representative aroma components in stir-fried highland barley. With the increase of stir-frying time, the fruity, herbal, flowery, and faint fatty aroma of raw highland barley changed to typical roasted highland barley-like aroma dominated by cocoa-like, roasted, nut-like and faint fruity aroma. According to the results of hierarchical cluster analysis (HCA) and principal component analysis (PCA), the similarity between 8 and 11 min stir-fried samples was high, indicating that their aroma composition and content were comparatively consistent, but the content of heterocyclic compounds was the highest at 8 min of stir-frying, so that 8 min could be considered as the most suitable stir-frying time for highland barley. This study can provide a theoretical basis for the development of roasted highland barley foods.

Key words: highland barley; stir-frying method; stir-frying time; volatile flavor; gas chromatography-mass spectrometry