Abstract: The physicochemical properties and hydroxyl radical scavenging capacity of coarsely ground powder and superfine ground powders with different grinding times (1, 3, 5, 10, 20 and 30 min) of apple dietary fiber were measured. Besides, particle size measurement and structural observation were performed by laser particle size analyzer and scanning electron microscope. The results showed that after superfine grinding, the particle size of dietary fiber decreased; the swelling power, water solubility and cation exchange capacity significantly increased (P < 0.05), together with a significant increase in the hydroxyl radical scavenging capacity (P < 0.05). There was no significant change in water-holding capacity or bulk density (P > 0.05). The data from this study can provide a theoretical basis for the deep processing and utilization of apple dietary fiber in the food field.

Key words: apple, dietary fiber, superfine grinding, physicochemical properties, hydroxyl radical scavenging capacity