Effect of extrusion treatment on the functional properties and structure of pea protein

Objective: This study focuses on the effects of twin-screw extrusion on the functional properties and structure of pea protein. Methods: The color change of pea protein extrudates were analyzed by automatic colorimeter, the water holding capacity and emulsifying characteristics of pea protein were analyzed by chemical analysis. The microstructure of pea protein and its extrudates were observed by scanning electron microscope, and the secondary structure of the extrudates were analyzed by Fourier transform infrared spectroscopy. Results: After extrusion treatment, no significant difference was found in the color of pea protein, indicating that the pea protein had a better product color and the water holding capacity was significantly reduced （P＜0.05）, with the emulsibility and emulsification stability significantly increased （P＜0.05）. Scanning electron microscope showed that the microstructure changed obviously, resulting in protein aggregates with compact structure. The infrared spectrum showed that no new characteristic peaks appeared after extrusion treatment, but the secondary structure conversion occurred; β-sheet and α-helix structure transformed into β-turn and random coil structure, and the structural stability increased. Conclusion: After extrusion treatment, the pea protein retained its original product color, emulsification characteristics were significantly improved, the structure was dense and stability was enhanced.