Functional drink powders from vertical-stone-milled oat and highland barley with high dietary-fiber levels decrease the postprandial glycemic response

Abstract

• Vertical stone mill was used to get oat and highland barley bran powder (SOB and SHB) • Two drink powders (SOB-D and SHB-D) were obtained from SOB and SHB by extrusion. • SOB-D and SHB-D had lower in vitro starch hydrolysis, higher RS level than control. • SOB-D and SHB-D had lower glycemic response than a wheat bun in healthy subjects. • Higher breath H 2 level via consuming SOB-D and SHB-D was observed in healthy subjects. To extend the application of oat and highland barley in the food industry, a vertical stone mill was first used to process two bran powders (SOB and SHB). Compared with commercial flours, SOB and SHB were more thermally stable with higher protein and dietary fiber levels while lower starch content. Furthermore, two drink powders (SOB-D and SHB-D) were extruded from SOB and SHB, with significantly increased resistant starch (the highest value 6.3% in SHB-D). Starch-protein complexes were detected in both SOB-D and SHB-D, inducing lower in vitro digestibility and human postprandial glycemic response than those of wheat flour steamed bun. Human Intake of SOB-D and SHB-D elevated the level and extended duration of breath H 2 , indicating stronger colonic fermentation. It identified combination of vertical stone milling and extrusion was an effective way to produce oat and highland barley functional food with low digestibility and high potential of colonic fermentation ability.