Structure Characterization and Functional Properties of Flaxseed Protein-Chlorogenic Acid Complex

This study aimed to investigate the effects of the covalent binding of flaxseed protein (FP) and chlorogenic acid (CA) on the structure and functional properties of FP-CA complexes fabricated using the alkali method. The results suggested that the encapsulation efficiency of CA encapsulated by FP ranged from 66.11% to 72.20% and the loading capacity of CA increased with an increasing addition ratio of CA with a dose-dependent relationship, which increased from 2.34% to 10.19%. The particle size, turbidity, zeta potential and PDI of FP and the FP-CA complexes had no significant discrepancy. UV-Vis and fluorescence spectra showed the existence of the interaction between FP and CA. SEM images showed that the surface of the FP-0.35%CA complex had more wrinkles compared to FP. Differential scanning calorimetry analysis indicated the decomposition temperature of FP at 198 °C was higher than that (197 °C) of the FP-0.35%CA complex, implying that the stability of the FP-CA complexes was lower than FP. The functional properties suggested that the FP-CA complex with 1.40% CA had a higher water holding capacity (500.81%), lower oil holding capacity (273.495%) and lower surface hydrophobicity. Moreover, the FP-CA complexes had better antioxidant activities than that of FP. Therefore, this study provides more insights for the potential application of FP-CA covalent complexes in functional food processing.