Effect of high moisture extrusion cooking on protein-protein interactions of pea (Pisum sativum L.) protein isolates

This study focuses on protein alterations in fibrous meat substitutes produced by high moisture extrusion cooking of pea protein isolates. Three commercially available pea protein isolates and their respective extrudates were evaluated regarding their amino acid composition, molecular weight distribution and protein-protein interactions. Extrusion had no effect on the degree of hydrolysis and amino acid composition indicating that the thermal and mechanical energy during extrusion did not cause the formation of peptide bonds or the degradation of amino acids due to Maillard reactions. Decrease of protein solubilised from extrudates in a buffered solution containing urea indicated that the structural integrity of extrudates could be attributed mainly to covalent disulphide bonding and, to a smaller extent, to non-covalent interactions. Additionally, the disappearance of legumin bands in extrudates as determined by electrophoresis could be explained by its participation in a macromolecular network that was aggregated and cross-linked via disulphide bonds. This study contributes to a better understanding of the way the proteins interact during extrusion of pea protein isolates.