Modification of chitooligosaccharide with phenolic acids for extended cherry tomato preservation and quality...

Coating materials extend fruit shelf life by forming protective barriers against microbial growth and preserving freshness. Herein, three chitooligosaccharide (COS) derivatives were synthesized via grafting protocatechuic acid, caffeic acid, and gallic acid onto COS, with their structures characterized. Fourier transform infrared spectroscopy confirmed successful grafting via amide linkages. ¹H NMR analysis revealed new absorption peaks between 6.5 and 7.5 ppm, attributable to the grafted phenolic acids. Compared to ungrafted COS, the derivatives exhibited enhanced antioxidant activity and superior bacteriostatic activity. Spraying 2 mg L^-1 derivatives on cherry tomatoes significantly reduced decay (33.7%-44.7%), browning (14.3%-23.6%), and the accumulation of reducing sugars (41.9%-49.6%) and soluble solids (13.3%-22.3%) during storage. These derivatives alleviated oxidative stress by enhancing catalase activity and reducing malondialdehyde levels, while inhibiting polyphenol oxidase to slow phenolic degradation and delay senescence. This grafted COS derivative coating offers enhanced biocompatibility for cherry tomato preservation systems.