Physicochemical and antioxidant properties of dietary fibers from Qingke (hull-less barley) flour as affected by ultrafine grinding

The effect of particle size of Qingke flour and particle size of dietary fiber (DF) on physicochemical and antioxidant capacities of DF was investigated. Qingke and extracted DF were ground by regular and ultrafine grinding and their particle sizes were determined using laser diffraction method. The results indicated that ultrafine grinding could effectively pulverize DF particles to submicron scale; the particle size distribution was close to a Gaussian distribution. The soluble DF in Qingke flour was increased significantly after ultrafine grinding. With the decrease of particle size, the water holding capacity (WHC) of Qingke DF was reduced (p<0.05), while the swelling capacity, oil binding capacity (OBC), and nitrite ion absorption capacity were increased (p<0.05), and the water retention capacity (WRC) had no significant change. The antioxidant activities of Qingke DF were increased after ultrafine grinding. Micronized insoluble DF showed increased DPPH radical scavenging activity and ferric reducing antioxidant power.