Impact of Processing Parameters on Physicochemical Properties and Biological Activities of Qingke (highland Hull‐less Barley) Treated by Steam Explosion

In this study, steam explosion (SE) was used to process Qingke (highland hull-less barley). Under the optimum conditions of steam pressure (P) of 2.34 MPa, processing time (T) of 37.0 s and initial water content (W) of 10.0%, the optimum values of expansion ratio (ER), unpopped kernel ratio (UKR), total polyphenol content (TPC), total flavone content (TFC), and antioxidant index (ABTS) were 3.24, 0.192, 3.81 mg GA/g DW, 3.24 mg rutin/g DW and 14.0 mg ASC/g DW, respectively. Optimization of physicochemical properties showed that SE resulted in excellent expansion properties of Qingke while preserving its active components and antioxidants. By comparing the analysis results of scanning electron microscopy (SEM), hydration, vitamin E, beta-glucan, pentosan, and dietary fiber of the SE treated Qingke with the raw and traditional roasting treated Qingke, SE has been demonstrated to be a better processing technology for Qingke and could well maintain the nutrients of Qingke. Practical applications Qingke is a special type of barley without hull that mainly grows in highlands. The processing conditions for Qingke with steam explosion have been successfully optimized and the shape and nutritional value of Qingke can be well preserved. The comparison between traditional roasted and steam explosion treated Qingke showed that steam explosion technology can better puff up and retain the nutrients of Qingke. This work provides an efficient processing method for comprehensive utilization of Qingke.