Physicochemical properties of different pea proteins in relation to their gelation ability to form lactic acid bacteria induced yogurt gel

Three commercial pea proteins and a laboratory sample (PL) were assessed for their physicochemical properties (subunit composition, secondary structure, surface hydrophobicity, solubility) and gelation properties (rheology, texture, intermolecular forces) in fermentation induced yogurt gel. The results showed that the dissociation of legumin was occurred in all three commercial pea proteins, accompanied by the formation of large protein aggregates. The contents of α-helix and β-sheet were significantly lower in the commercial pea proteins than PL (p < 0.05). However, commercial pea protein prepared by sour liquid processing method (PS) showed relatively higher solubility and β-sheet content than both of the two commercial samples prepared by alkali extraction isoelectric precipitation methods (PA). In addition, rheological properties results revealed that the gelation abilities of the three commercial pea proteins declined compared with the PL. Among all commercial pea protein-based yogurt gels, PS-based yogurt gel presented a higher hardness than PA-based yogurt gels. According to this study, the decreased gelation ability of commercial pea proteins could attribute to the dissociation of legumin and decrease in β-sheet structure, which weaken the hydrophobic force to form yogurt gels induced by lactic acid bacteria.