Effect of Heat Treatment on the Molecular and Functional Properties of Pea Protein Isolate

This work aimed at understanding the effect of heat treatment on the properties and functionalities of pea protein isolate (PPI). PPI was characterised using thermogravimetric methods coupled with evolved gas analysis, differential scanning calorimetry, and X-Ray powder diffraction. As water is an integral component in determining protein properties, inelastic neutron scattering was further used to study water populations in the PPI powder. Hydration time was identified as key in determining solubility. Heat treatment resulted in partially denatured, more soluble, less thermodynamically stable, and less crystalline PPI compared to the control. Heating, often associated with protein aggregation and particle size increase, was found to reduce PPI particle sizes, which was attributed to the disruption of non-covalent interactions. During emulsification, these features enhanced formation of smaller drops, stable against coalescence. Compared to the control, the heat-treated PPI produced emulsions with increased shear thinning (power law index of 0.6 compared to 0.9) and consistency (≈10 times higher), as it has been previously reported for emulsions with fine, compared to coarse, droplets. Acid-induced gels of the heat-treated PPI were ≈4 times more elastic (G’) compared to the control. Overall, this work contributes towards the design of plant-based foods with predictable characteristics by understanding the link between protein physicochemical properties and food functionality.