Influence of phenolic compounds on the structural characteristics, functional properties and antioxidant activities of Alcalase-hydrolyzed protein isolate from Cinnamomum camphora seed kernel

In this study, protein isolate (PI) and protein-phenolic complex (PPC) were prepared from Cinnamomum camphora seed kernel (CCSK). The effects of naturally present phenolic compounds on the structural characteristics, functional properties and antioxidant activities of CCSK protein before and after hydrolysis by Alcalase were evaluated. The formation of PPC was confirmed by the ultraviolet–visible and intrinsic fluorescence spectra. The resultant PPC hydrolysates (PPHs) had higher degree of hydrolysis values than PI hydrolysates (PHs). Fourier transform infrared spectroscopy analysis showed that PHs and PPHs had more disordered structure, with the increase of random coil content. PI and PPC had similar solubility curves in the pH range of 2.0–9.0. However, hydrolysis led to a decrease in the solubility of PHs and PPHs at pH 2.0 and 3.0, and the solubility of PPHs was higher than that of PHs at pH 6.0 and 7.0. In addition, PPC exhibited better emulsifying properties and stronger antioxidant activities than those of PI before and after hydrolysis. These results indicated that PPC and PPHs obtained from CCSK may have great application potential in food industry as functional ingredients.