Effects of preharvest calcium chloride application on ripening and postharvest quality of papaya during cold storage and subsequent ambient shelf life

Papaya fruit is highly susceptible to post-harvest deterioration, resulting in significant loss of fruit quality during storage. The effects of preharvest calcium chloride (CaCl₂) spray at the green fruit stage with different concentrations (0.5%, 1%, and 2%) on postharvest quality and storage performance were evaluated. Fruits were collected at the color-break stage (25% yellow surface) and stored under cold conditions (10 ± 2 °C, 80 ± 5% RH) for 21 days and then stored in ambient conditions (25 ± 2 °C, 60 ± 5% RH) for 2 days. Samples were analyzed using two-way factorial analysis of variance (ANOVA), followed by the least significant difference (LSD) test at ( p < 0.05). The 2% treatment resulted in the lowest rates of weight loss, disease incidence, chilling injury, and color change, and retained fruit firmness. In the treated fruits, the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were found to be higher than those of the untreated fruits, reflecting higher antioxidant enzyme activities following CaCl₂ treatment, and the acidity, ascorbic acid, total phenolic content, and antioxidant activity were higher than those of the untreated fruits. 2% treated fruits exhibited lower ethylene production, electrolyte leakage, malondialdehyde, and hydrogen peroxide accumulation, along with changes in browning-related enzyme activities. Moreover, it suppressed the rise in soluble solids content and the ripening index, as well as the activities of enzymes involved in cell wall degradation, such as cellulase, polygalacturonase, and pectin methylesterase. Overall, the use of 2% CaCl₂ before harvest proved effective in maintaining postharvest quality with improved storage performance in papaya fruit.