Preharvest Aqueous Chitosan Application Enhances the Quality and Storability of Litchi Fruit

To meet consumer expectations for larger litchi fruits and better postharvest storage quality, this study assessed the effects of preharvest chitosan application on litchi fruit size, weight, postharvest quality and storage performance. Litchi fruits were sprayed with a commercial aqueous chitosan formulation (Kadozan) in five different concentrations, namely, 1:250 (VKadozan: VKadozan + Water), 1:500, 1:750, 1:1000 and 0:1000 (control), at 45, 55, and 65 days after full blossom (AFB), and then harvested at commercial maturity (90 days AFB). After harvest, the fruit were cleaned, air-dried, packaged, and subsequently stored at room temperature (25 ± 1 °C). The results revealed that preharvest Kadozan treatment produced heavier and larger fruits with higher vitamin C at harvest. During storage, it delayed the decline in total soluble solids, soluble sugars, and vitamin C in the aril while preserving higher pericarp anthocyanin, chlorophyll, carotenoid, and flavonoid contents. Kadozan treatment also reduced respiration rate, weight loss, and cell membrane permeability, increased total phenolics and decreased polyphenol oxidase activity, leading to a lower browning index. Notably, it enhanced lignin, upregulated phenylalanine ammonia-lyase, chitinase and β-1,3-glucanase activities, and accordingly suppressed disease development and improved marketable fruit rate. In conclusion, among the tested treatments, the 1:750 Kadozan application was the most effective in improving fruit quality at harvest, delaying postharvest senescence, and enhancing storage performance, thus offering a practical strategy for both preharvest quality improvement and postharvest quality maintenance of litchi fruits.