Structural characteristics of pea protein isolate (PPI) modified by high-pressure homogenization and its relation to the packaging properties of PPI edible film

This study modified pea protein isolate (PPI) structure by high-pressure homogenization (HPH) and investigated PPI structural relation to the packaging properties of PPI film. HPH decreased PPI particle size, reduced surface charge, increased surface hydrophobicity, and increased free sulfhydryl, providing greater potential for covalent bonding during film formation. HPH decreased opacity of PPI films from 7.39 to 4.82 at pressure of 240 MPa with more homogeneous surface. The tensile strength and elongation at break were increased from 0.76 MPa to 1.33 MPa and from 96% to 197%, respectively, after treatment at 240 MPa. This improvement was due to the enhanced protein-protein and protein-glycerol hydrogen bonding as evidenced by FTIR. Increased beta-sheet and decreased alpha-helix by HPH was also observed, and beta-sheet was highly correlated to film tensile strength (Pearson coefficient of 0.973, P < 0.01). Principle component analysis visualized the influence of HPH treatment, and confirmed the association between structural characteristics and film properties.

Automated summary

This study investigated the modification of pea protein isolate (PPI) structure using high-pressure homogenization (HPH) and its impact on the packaging properties of PPI film. HPH effectively reduced particle size, changed surface properties, and improved film strength and elongation. The enhancement was mainly attributed to increased protein-protein hydrogen bonding.