Changes in structure, functional properties and volatile compounds of Cinnamomum camphora seed kernel protein by Maillard reaction

Abstract

In this study, Cinnamomum camphora seed kernel protein isolate (CPI)−dextran (DX) model system was used to investigate the impacts of reaction temperatures (70−100 °C) and times (1−4 h) on the structure, functional properties and volatile compounds of Maillard reaction products (MRPs). The formation of MRPs was confirmed by SDS-PAGE, ultraviolet absorption and degree of glycation. Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy showed that the secondary structure of MRPs tended to be more regular than native CPI. Moreover, MRPs had a lower free sulfhydryl group content and higher surface hydrophobicity than native CPI. Fluorescence spectra revealed that the tryptophan residues of CPI were transferred to a more hydrophobic microenvironment. The solubility and emulsifying stability of CPI were decreased, while the foaming activity, foaming stability, emulsion stability and apparent viscosity of CPI were significantly improved (p < 0.05) after Maillard reaction. Furthermore, MRPs exhibited significantly improved (p < 0.05) thermal stability and ABTS+• radical scavenging activity than native CPI, while the DPPH+ radical scavenging activity and ferric reducing power were decreased. In addition, volatile compounds, including aldehydes, ketones, benzenes and esters, were identified in MRPs. These results provide a theoretical guidance for future studies on CPI-DX conjugates.