Maintenance of the antioxidant capacity of fresh-cut pineapple by procyanidin-grafted chitosan

•Procyanidin-grafted chitosan (PCCS) was prepared by a free radical-mediated method.•PCCS was characterized by FTIR, 1H NMR, XRD, TGA, and DSC.•PCCS prevented the loss of vitamin C and total phenols in fresh-cut pineapple.•PCCS suppressed the PPO and POD activities of fresh-cut pineapple.•PCCS maintained the antioxidant capacity of fresh-cut pineapple. Chitosan (CS) is a suitable biomaterial used for edible coatings. In this work, CS was grafted with procyanidin (PC), a potent natural antioxidant, by a free radical-mediated procedure to improve the protective effect on the antioxidant capacity of fresh-cut pineapple. The resultant PC-grafted CS (PCCS) had a high grafting degree of 340.9 g kg−1 and was characterized by several instrumental methods. Then, PCCS was used as an edible coating for fresh-cut pineapple to maintain the antioxidant capacity of the fruit. The results show that the retention content of vitamin C in PCCS-treated fresh-cut pineapple was 269.2 g kg−1 after 14 d of storage, which was higher than that of both the CS-treated sample and the control. Similarly, the PCCS-treated sample also showed a higher total phenolic content. Moreover, PCCS treatment significantly suppressed the increase of the polyphenol oxidase and peroxidase activities of fresh-cut pineapple during cold storage. Consequently, the PCCS-treated sample exhibited higher antioxidant capacity than the CS-treated sample and the control. In addition, PCCS treatment could effectively prevent the weight loss of fresh-cut pineapple and inhibit microbial growth on the fruit. Our results suggest that PCCS could be a candidate for coating biomaterials to maintain the antioxidant capacity of fresh-cut pineapple during cold storage.