Enhancing the dispersibility of commercial pea protein ingredients using stirred media milling: Potential mechanisms of action

Abstract

This study found that stirred media milling (SMM) showed great potential in enhancing the functional properties of commercial legume proteins. The effects of SMM on protein dispersibility and structure in 5% pea protein solutions were investigated. The milling increased pea protein dispersibility index from around 12 to 99%, over an 8-fold increase. During milling, the D[4,3] of protein particles decreased from around 122 μm to 320 nm and the magnitude of the zeta potential increased from 21.6 to 30.0 mV. Microscopy analysis revealed that the morphology of the protein particle changed from aggregated, irregular, and dense before milling to uniformly distributed and spherical after milling. And hydrophobic interactions were the primary intramolecular forces maintaining the structure of the water-dispersible protein particles. Intrinsic fluorescence intensity, surface hydrophobicity, and free sulfhydryl group analysis of the pea proteins increased after milling, and there was a net change in the secondary structure of the proteins from β-sheet and random coil to α-helix and β-turn. SDS-PAGE analysis revealed that insoluble protein aggregates transformed into water-dispersible ones after milling. These results suggested that the conformation and aggregate state of protein molecules were changed during milling. This study indicates that the stirred media milling is a simple and effective means of enhancing pea protein dispersibility, which could expand the application of plant protein in the food industry.