Modification of the structural, emulsifying, and foaming properties of an isolated pea protein by thermal pretreatment

Abstract

ABSTRACTPea protein isolate (PPI) prepared through isoelectric protein precipitation was heat-treated between 50°C and 100°C. The effect of heat treatment on the structural and functional properties of proteins was evaluated. Native gel electrophoresis showed the formation of protein aggregates (molecular weight ≫ 200 kDa) in the temperature range of 80–100°C. Intrinsic fluorescence data suggested that protein denaturation reached its highest level at pH 3.0. The formation of oil-in-water emulsions (1:5 oil:water volume ratio) was positively impacted by pH increase as evidenced by the decrease of minimum oil droplet size (d4,3) from 26 μm at pH 5.0 to 22 μm at pH 7.0 (P < 0.05). In contrast, heat pretreatment led to decreasing emulsion properties at pH 3.0 with d4,3 values increasing from 27 μm to 80 μm (P < 0.05). Regardless of pH applied, all heated PPI samples displayed low foaming properties.