Color, Starch Digestibility, and In Vitro Fermentation of Roasted Highland Barley Flour with Different Fractions

Highland barley (HB) is commonly milled into flour for direct consumption or further processed with other food formulations. Nevertheless, the association between milling and HB flour properties remains lacking. This work studied the effect of particle sizes (coarse, 250-500 mu m; medium, 150-250 mu m; fine, <150 mu m) on physicochemical and nutritional properties of raw and sand-roasted HB flour. Gelatinization enthalpy decreased with increasing particle sizes of raw HB flour, while no endothermic transitions were observed in sand-roasted flour. Sand roasting destroyed starch granules and decreased short-range molecular order. Starch digestibility increased while total short-chain fatty acids (SCFAs) production decreased with decreasing particle sizes in all samples. The relative crystallinity of sand-roasted HB flour decreased by 80-88% compared with raw samples. Sand roasting raised in vitro starch digestibility, while total SCFAs during in vitro fecal fermentation decreased. Sand-roasted HB flour with particle sizes <150 mu m had the highest starch digestibility (94.0%) but the lowest production of total SCFAs (1.89-2.24 mM). Pearson's correlation analysis confirmed the relationship between the nutritional qualities of HB flour and milling.

Automated summary

Particle sizes have an impact on the physicochemical and nutritional properties of highland barley flour, and sand roasting process can increase starch digestibility while decreasing the production of total short-chain fatty acids.