Postharvest wax coating treatment extends shelf life of climacteric fruits by delaying ripening, improving storage quality and antioxidant potential

Abstract

Apples (Malus domestica) and pears (Pyrus ussuriensis) are typical climacteric fruits that mature with ethylene release, resulting in a short shelf life. Wax coating is widely used as a postharvest treatment to extend shelf life and maintain fruit quality. However, its influence on fruit storage and preservation remains insufficiently explored. In this study, apples and pears were treated with various concentrations of liquid wax. The treatment delayed color change during storage, inhibited ethylene production and respiration identity, and alleviated reductions in fruit firmness, titratable acidity, and ascorbic acid (AsA) content. An in-depth investigation was conducted on fruits treated with an 80% concentration of liquid wax. Compared with the control, wax-coated fruits exhibited a denser epidermal structure, slower chlorophyll degradation and carotenoid accumulation, and alterations in soluble sugar composition, particularly a significant reduction in sucrose content. Additionally, wax coating enhanced phenylalanine ammonia-lyase activity while reducing the activities of polyphenol oxidase, peroxidase, superoxide dismutase, and catalase. These changes in enzymatic activity inhibited the declines in total phenolic and total flavonoid contents and suppressed the accumulation of malondialdehyde, superoxide anion, and hydrogen peroxide. Quantitative real-time polymerase chain reaction analysis further indicated that wax coating altered the expression levels of genes associated with these physiological responses. Collectively, these findings suggested that wax coating formed a protective film on the fruit surface, effectively delaying ripening, preserving nutritional quality, and enhancing antioxidant capacity. This study provides novel theoretical insights into the postharvest storage and preservation of climacteric fruits.