Synergistic interactions between pea protein isolate and rapid-swelling starch

Abstract

The viscosity of 5% w/v suspensions containing thermally inhibited (TI), chemically modified (CM), and granular cold-swelling (GCS) starch were assessed with an increasing fraction of a pea protein isolate (PP1). The system was treated as a biopolymer network, where the viscosity exhibited shear thinning behaviour that was best modelled using a Carreau model. Synergistic interactions between PP1 and TI starch were discovered, where the addition of PP1 caused a significant increase (p < 0.05) in viscosity, reaching a maximum between 0.2–0.25 PP1 mass ratio. The interactions were predominantly electrostatic, with more minor contributions from hydrogen bonding. Two additional pea protein isolates, PP2 and PP3, were also investigated; however, enhanced viscosity interactions were limited to PP1. The functional properties of the proteins were assessed, and it was concluded that protein-starch interactions could be enhanced by using a protein with increased water holding capacity (WHC), a greater α-helix: β-sheet ratio and displaying a less aggregated state exemplified by a higher proportion of lower molecular weight fragments.