Comparison of apple polyphenol-gelatin binary complex and apple polyphenol-gelatin-pectin ternary complex: Antioxidant and structural characterization

Abstract Polyphenol-gelatin binary complex and polyphenol-gelatin-pectin ternary complex were synthesized. The differences in antioxidant activity between the binary complex and ternary complex were evaluated by using ABTS, DPPH, and reducing power assays. The differences in structural characterization between the binary complex and ternary complex were investigated by scanning electron microscopy (SEM), nuclear magnetic resonance (1H and 13C NMR), and Fourier transform infrared (FT-IR) spectroscopy. The reducing power assays of the ternary complex was greater than that of the binary complex. The maximum of ABTS•+ scavenging activity of the binary complex and the ternary complex was 98.1% and 99.3%, respectively, and the maximum DPPH• scavenging activity was 84.7% and 87.6%, respectively. The results of structural characterization showed that they were very similar in structure. Both complexes are mainly composed of hydrogen bonds and hydrophobic interactions, but the ternary complex is more tightly bound. In addition, the surface is smoother, and the gap is smaller.