Physicochemical properties and antioxidant potential of protein isolate from camellia cake (Camellia oleifera Abel.): Effect of different processing techniques on industrial scale

This study aimed to assess the effects of industrial-scale oil-pressing techniques (hydraulic pressing (HP), twin-screw pressing (TP)), and organic solvent extraction (OE) on the physicochemical properties and antioxidant activities of protein isolates derived from Camellia (Camellia oleifera Abel.) seed cakes. The predominant protein fractions in camellia seed cake were albumin (32–37 mg/g) and glutelin (19–27 mg/g), and the twin-screw pressed cake had a lower total protein content than the others. Spectral analysis showed that the α-helix content increased at the expense of random coil content in proteins from HP and TP cakes, indicating that extrusion altered the structure of the protein. The camellia seed protein particle size from HP and TP cakes was significantly reduced compared to that from the OE cake. The proteins obtained by HP and TP had stronger antioxidant activities than those obtained by OE. This research presents the potential for further applications of camellia seed cake protein to be utilized as antioxidants and emulsifiers in the food industries.