Evaluating the Impact of Chitosan-Based Coating Enriched with Green-Synthesized Zinc Oxide Nanoparticles for Enhancing Postharvest Quality of Kiwifruit (Actinidia deliciosa)

Abstract

Kiwifruit ( Actinidia deliciosa ) is a frequently consumed fruit and has high economic value due its nutritional value, including phenolic compounds, flavonoids, and vitamins. The postharvest quality of the kiwifruit is limited due to its perishability and susceptibility to deterioration during storage. Edible coatings are an effective and eco-friendly alternative to synthetic fungicides for preserving the postharvest quality and extending shelf life of fresh produce. This study assessed the effect of chitosan (CH) enriched with green-synthesized zinc oxide nanoparticles (ZnO-NPs) on maintaining the postharvest quality of kiwifruit. The ZnO-NPs were synthesized using celery ( Apium graveolens L.) leaf extract and incorporated into CH (2%) at 0%, 0.4%, 0.8%, and 1.2% to form the composite coatings CH, CH + 0.4% ZnO-NP, CH + 0.8% ZnO-NP, and CH + 1.2% ZnO-NP, respectively. Fruit without any visible defect were dipped for 2 min in the respective coatings, and uncoated fruit were used as controls. Thereafter, fruit were air-dried for 30 min and then packed in open-top commercial boxes and stored at ambient temperature (21 ± 1 °C and 90 ± 5% relative humidity) to assess postharvest quality at 4-day intervals during the 12 days of shelf life. Fruit quality parameters, including mass loss, firmness, total soluble solids (TSS), total titratable acid (TTA), total chlorophyll content, total phenolic content, total flavonoid content, ascorbic acid content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, were assessed. The findings indicated that CH + ZnO-NP coatings effectively preserved postharvest quality of kiwifruit during shelf life compared with CH alone and control. Fruit coated with CH + 1.2% ZnO-NP and CH + 0.8% ZnO-NP exhibited lower mass loss, TSS, and TTA, as well as high firmness, total chlorophyll, total phenolic, total flavonoid and ascorbic acid contents, and DPPH assay at the end of shelf life compared with other treatments and control. This could be attributed to the influence of ZnO-NPs on improved barrier ability of the coating material, which delayed ripening and minimized external damage during shelf life. Therefore, CH coating enriched with ZnO-NPs at concentrations between 0.8% and 1.2% is recommended as an eco-friendly alternative for preserving postharvest quality and extending the shelf life of kiwifruit at ambient conditions.