Dissociation of aleurone cell cluster from wheat bran by centrifugal impact milling

Abstract

Wheat aleurone which contains most of the nutritionally important substances of wheat bran has been widely investigated, and electrostatic separation based on the distinct electrical properties of bran tissues has been proven to be effective for the enrichment of aleurone layer. In order to obtain a suitable starting material containing single-layer bran strips for the electrostatic separation, centrifugal impact milling was utilized to dissociate wheat bran constitutive tissues. During centrifugal impact milling, the outer pericarp was detached when the particle size of the fragments decreased to approximate 460μm, whereas the aleurone layer consisted of 20–30 intact cells in single-layer was completely dissociated until the particle size decreased to about 200μm. Moreover, the detached behaviors of bran tissues were well explained by the relationship of their elastoplasticities, the rupture-energy and peeling force generated by the rotating blade tip. After centrifugal impact milling and sieving, the bran fraction with the median particle diameter of 144μm contained 61% single-layer aleurone cell clusters, indicating that it could be a superior starting material for the electrostatic separation of wheat aleurone.