Modulating rice starch physicochemical and in vitro digestive properties with ball-milled pea protein isolate: Effect of ball-milling time.

Strengthening starch-protein intermolecular interactions is critical for modulating the physicochemical properties of starch via proteins. In this study, pea protein isolate (PPI) was pretreated by ball-milling for different durations (0, 10, 20, 30, 40 min), and the effects of milled PPI on the physicochemical properties and in vitro digestibility of rice starch (RS) were investigated. Compared with native PPI, ball-milling treatment of PPI (40 min) reduced the swelling power and water absorption capacity of PPI-RS mixtures by 5.38% and 6.39%, respectively, while increasing their solubility by 21.25%. Furthermore, ball-milling treatment of PPI weakened the short-range order of starch molecules and decreased the gelatinization enthalpy, peak viscosity, trough viscosity, final viscosity, breakdown, setback, gel hardness of PPI-RS composite mixtures. In vitro digestion tests revealed that ball-milling treatment of PPI (40 min) retarded starch digestion in PPI-RS composites, resulting in a 23.78% increase in resistant starch content. Notably, no significant further changes (p > 0.05) in the values of gelatinization enthalpy, setback value, gel hardness, and rapidly digestible starch content were detected when the ball-milling duration exceeded 20 min. This work can provide useful guidelines for developing novel starch-based foods with high nutritional quality and low glycemic index.