Effect of airflow impact milling on the physicochemical properties, microstructure, and flavor of defatted rice bran

Abstract

The influence of airflow impact milling (AFIM) on the particle size, physicochemical properties, microstructure, and flavor of defatted rice bran was investigated. With the decrease of feed speed and the increase of milling times, AFIM reduced the average particle size of defatted rice bran to a maximum of about 6.04 μm. At this time, its whiteness and soluble dietary fiber content increased by 17% and 36.6%, respectively, and the insoluble dietary fiber content decreased by 16.4%. AFIM increased the cation exchange capacity, water solubility index, and swelling capacity of defatted rice bran, but decreased the water and oil holding capacities. Moreover, scanning electron microscopy results showed that AFIM changed the microstructure of defatted rice bran to provide the ultrafine powders with good uniformity. A total of 37 volatile substances in defatted rice bran were identified by GC-IMS. The release of aromatic odors such as fruit, nutty, and sweet aromas from defatted rice bran after AFIM increased, improving its flavor quality.