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

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 H2, 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.