Effect of superheated steam treatment on endogenous β-glucan and gel properties of highland barley whole flour: Changes in gel structure and starch digestibility.

The gel properties of highland barley (HB) whole-flour gel depend on the behavior of starch, endogenous β-glucan, and protein. This study examined how thermal pretreatments changed these components and gel properties. HB kernels were treated with superheated steam (SS; 140-180 °C) and compared with steaming and stir-frying. Thermal treatment increased the molecular weight of β-glucan isolated from HB flour, with the highest value in SS-180 (2.23 × 105 g/mol). Fourier transform infrared spectroscopy showed thermal treatment-associated increases in starch short-range order and protein α-helix and β-turn proportions. SS-160 formed a more uniform matrix with smaller pores, had lower water mobility, and showed the highest springiness. In contrast, SS-180 showed larger and more irregular pores and lower springiness than SS-160 but had the strongest inhibitory effect on starch hydrolysis. These findings provide insight into the contribution of SS-induced changes in endogenous β-glucan, starch, and protein to HB whole-flour gel properties.