Thermal stabilization is efficient for slowing lipid degradation and prolonging the shelf life of highland barley, but the impacts of different thermal stabilized treatments on highland barley and possible chemical reactions remain unclear. The effects of thermal stabilization treatments (bake, far-infrared, fry, microwave and steam) on the enzymes, lipids and aroma profiles of highland barley flour (HBF) were investigated in this study. Thermal stabilization significantly decreased the contents of ash and GABA. Baked HBF exhibited the lowest fatty acid value and peroxide value. Untreated HBF had higher lipase and lipoxygenase activities and fried mostly inactivated these enzymes. All thermal stabilization treatments increased the catalase activities and fried showed the higher level. Thus, fried might be an effective method to stabilize the HBF. The high temperatures during stabilizing triggered the complex reactions, leading to the loss of some volatile compounds, and in the meantime the formation of others such as furans and aldehydes. These productions contributed to the unique aroma profiles of different HBFs. Furthermore, a chemometric approach was used to analyze the changes of thermal stabilized treated HBFs and to identity six key volatile compounds, which provided important knowledge on possible chemical reactions caused by thermal stabilization. Overall, these results provide the theoretical basis for the wider application of thermal stabilization technologies in highland barley processing.

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The flavor profile of five brands of instant vermicelli seasonings were identified by headspace solidphase micro-extraction coupled with gas chromatographymass spectrometry (HS-SPME/GC-MS) and electronic nose (e-nose). GC-MS showed that the volatile compounds of instant vermicelli seasonings were significantly different. Alkenes, alcohols, aldehydes and ketones were the major volatile compounds in instant vermicelli seasonings. The seasonings could be classified based on differences in volatile compounds. The overall volatiles profiles were also analyzed by e-nose. E-nose determination and GC-MS statistical analysis had similar results. The volatile compounds showed good correlation with e-nose sensors according to partial least square regression models. Both methods had good potential application in evaluating flavor quality and differentiating among instant vermicelli seasonings.

The effects of transglutaminase (TGase) and ascorbic acid (AA) on the processing properties of composite buckwheat dough (CBD) and composite buckwheat steamed bread were investigated in this study. Both TGase and AA significantly enhanced the peak and trough viscosity of CBD. With the addition of TGase or AA, storage modulus (G 0 ) and viscous modulus (G″) of CBD increased first and then decreased, which was corroborated by data on protein secondary structure. Results revealed TGase and AA promoted protein crosslinking, and that TGase led to a more continuous, smoother dough structure than did AA. TGase and AA strongly affected hardness, adhesiveness and cohesiveness of CBD with a positive aspect. Compared with the steamed bread made with pure buckwheat, that made with composite buckwheat flour with TGase or AA had significantly lower hardness and gumminess rates within 30-60 min but no significant results were noted within 0-30 min.

The nutritional, processing, functional and edible qualities of three highland barley flour (HBF) with different pearling rates were assessed in this study. As expected, ash and dietary fiber content of three HBF showed downward trends with the increase of pearling rates, and a decreased of β -glucan content was observed. However, the total phenol and γ-aminobutyric acid contents in three HBF were overall the highest with 4% pearling rate. Pearling treatment slowed down the digestion speed of starch by decreasing the content of rapidly digestible starch and changed the thermomechanical properties. With the exception of total phenolic content and anthocyanin content, unpearled HBF showed much higher antioxidant activities such as total antioxidant capacity and radicals scavenging ability than the pearled ones. Noodles made with pearled HBF presented the better cooking and texture characteristics, which attributed to the lower breaking rate, the shorter cooking time, the higher hardness, chewiness and resilience.