Effect of extrusion on physicochemical properties and antioxidant potential of protein isolate derived from Baijiu vinasse

Extrusion cooking is a green technology to manufacture distiller's grain food. In this study, effects of extrusion on the physicochemical properties and antioxidant potential of Baijiu vinasse protein isolate were investigated. Results showed that extrusion could effectively reduce the particle size (reduced from 275.07 ± 3.60 to 120.30 ± 1.13 nm), zeta potential, and surface hydrophobicity but increase the free sulfhydryl group of Baijiu vinasse protein isolate. Moreover, the unfolding, porous and amorphous structure was observed after extrusion by spectral analysis and X-Ray diffraction, endowing good solubility (increased from 59.26 ± 5.64% to 102.26 ± 3.21% at pH 7), foaming, and emulsifying stability. The in vitro protein digest of Baijiu vinasse protein isolates from extruded samples (200 °C, 150 rpm) exhibited most potent antioxidant activities. This study is the first to exploit extrusion as a feasible technology to produce Baijiu vinasse protein-based food. The results will be of great potential in future industrial application of Baijiu vinasse as a sustainable source of food proteins.