In this study, caffeic acid (CA) and chlorogenic acid (CGA) were incorporated onto chitosan (CS) using free radical grafting initiated by a hydrogen peroxide/ascorbic acid (H2O2/Vc) redox system. The structural properties of the CA (CA-g-CS) and CGA (CGA-g-CS) derivatives were characterized by UV–Vis absorption, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and thermal stability analysis. Then, the antioxidant and antibacterial properties were evaluated, and the effect of CGA-g-CS on the postharvest quality of Saimaiti apricot was studied. It proved that phenolic acids were successfully grafted onto the CS. The grafting ratios of CA-g-CS and CGA-g-CS were 126.21 mg CAE/g and 148.94 mg CGAE/g. The antioxidation and antibacterial activities of CGA-g-CS were better than those of CA-g-CS. The MICs of CGA-g-CS against E. coli, S. aureus, and B. subtilis were 2, 1, and 2 mg/mL. The inhibitory zones of 20 mg/mL CGA-g-CS against the three bacteria were 19.16 ± 0.35, 16.33 ± 0.91, and 16.24 ± 0.05 mm. The inhibitory effects of 0.5% CGA-g-CS on the firmness, weight loss, SSC, TA, relative conductivity, and respiration rate of the apricot were superior. Our results suggest that CGA-g-CS can be potentially used as an edible coating material to preserve apricots.
In this study, we incorporated gallic acid (GA) and salicylic acid (SA) onto chitosan (CS) using free radical grafting initiated by hydrogen peroxide/Vitamin C (H 2 O 2 /Vc) redox system. We characterized the structural properties of the GA (CS-GA) and SA (CS-SA) derivatives using UV-vis absorption, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and thermal stability analysis. We proved that these phenolic acids were successfully grafted onto the molecular skeleton of CS. We investigated the antioxidant and antibacterial properties of CS-GA and CS-SA and found that they had significantly higher antioxidant and antibacterial properties than native CS. Furthermore, the antioxidant ability increased with the increase in grafting ratios. Finally, in vivo tests showed that CS-GA could maintain the firmness and the content of soluble solids and titratable acids in Saimaiti apricots at cool storage. The storage period was prolonged by inhibiting the respiratory intensity of apricots. Our results suggest that CS-GA can be potentially used as an edible coating material to preserve apricots.
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