Physical Properties, Structural Characteristic and Antioxidant Activity of Moringa oleifera Seed Meal Subjected to Ball Milling Treatment

Abstract

This study aims to investigate the effects of ball milling time on the physical characteristics, structural features, and bioactive constituents of Moringa oleifera seed meal. The results demonstrated a significant reduction in particle size and an increase in specific surface area (SSA) with ball milling. However, an inverse relationship was observed between particle size and ball milling time. Prolonged ball milling time adversely affected water holding capacity (WHC), swelling capacity (SC), tap density (TD), angle of repose (AR), and angle of slide (AS) of Moringa oleifera seed meal. Conversely, it enhanced oil holding capacity (OHC) and brightness (L*). Ball milling also increased the solubilization rates of total phenols, total flavonoids, and crude polysaccharides, accompanied by a significant improvement in antioxidant capacity. Nevertheless, prolonged ball milling time led to a reduction in bioactive compounds to varying extents. Fourier transform infrared (FTIR) spectra analysis did not reveal the emergence of new chemical functional groups in any of the samples. X-ray diffraction (XRD) patterns exhibited consistent shapes across all samples, with a higher crystallinity index observed in treatments involving prolonged ball milling. Scanning electron microscopy (SEM) images illustrated alterations in the particle shape of Moringa oleifera seed meal, with increased surface roughness correlating with longer ball milling time. The ultrafine powder of Moringa oleifera seed meal shows potential as an ingredient in grain products or baked goods.