Abstract: In order to investigate the difference among pepper seed coat powders with different particle sizes for their processing and utilization, the effects of particle size on the color, microstructure, mid-infrared spectrum, adsorption characteristics, bioactives and antioxidant activity of black seed coat powders of pepper (Zanthoxylum bungeanum) were examined. Results showed that superfind grinding significantly reduced the particle size of the coarse powder, brightened the color, disrupted the cell wall, increased the water and oil holding capacity by 33.33% and 44.60%, respectively, and improved the heavy metal ion adsorption capacity. However, it did not alter the structure of functional groups in the powder. The dissolution of polyphenols and flavonoids from the superfine powder were increased by 15.93% and 11.24%, respectively, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity were enhanced significantly as compared with the coarse powder (P < 0.05). Therefore, superfine grindin could significantly improve the dissolution of active substances and effectively increase antioxidant activity, consequently leading to more effective utilization of black seed coat of pepper.

Key words: black seed coat of pepper, particle size, superfine powder, physicochemical characteristics