Heat-induced modifications of pea protein: Implications for solubility and digestion behaviour

Abstract

Plant proteins have become increasingly desirable due to their sustainability and proposed health benefits. This study initially examined the effects of heat treatment on the solubility of pea protein (PP) in a 3 % (w/w) protein solution, applying heat from 65 °C to 95 °C for varying durations across pH conditions ranging from 5.5 to 7.8. Subsequently, an advanced dynamic gastric digestion model—the Human Gastric Simulator—was employed to examine the in vitro gastric digestion behaviours of heat-treated and untreated PP. Results suggest that heat treatment reduces the protein aggregate size and enhances PP solubility, potentially due to a decrease in α-helix and β-turn structures or an increase in β-sheet content, as determined via Fourier transform infrared spectroscopy. Additionally, heat treatment elevated the surface hydrophobicity and free sulfhydryl group concentration of PP. During in vitro dynamic gastric digestion with pepsin, PP underwent notable structural and physical stability modifications. Unheated and heated PP exhibited small particles in the digesta and remained unaggregated throughout digestion. However, the heat-treated PP showed a smaller particle size during gastric digestion and a greater hydrolysis rate than the unheated protein. This study systematically evaluates the solubility and digestion behaviour of PP subjected to food processing conditions, highlighting its stability and structural changes that may influence the delivery of macronutrients from the stomach to the next phase of digestion.