Optimization of postharvest progesterone treatment to alleviate chilling injury in mango fruit, maintaining intracellular energy, cell wall stability, and antioxidant activity

Abstract

Mango is a tropical fruit that is highly susceptible to chilling injury (CI) when stored at low temperatures, resulting in reduced quality and shelf life. In this study, we investigated the potential of progesterone (PROG) treatment concentration and duration to reduce CI in mango during storage under low-temperature conditions and optimised the treatment using response surface methodology (RSM). The study was conducted over two consecutive seasons. The first trial was conducted using different submergence concentrations and periods (0, 1, 5, 10, 15, or 20 µM for 5, 10, 15, 20, or 30 min), the experimental data were analyzed using RSM to optimize and determine the optimal concentration and timing of treatment based on several measurements, including CI index, firmness, malondialdehyde, and electrolyte leakage. Based on this, the optimal conditions for PROG treatment were used, which were at a concentration of 12 µM for 15 min, and their different effects on fruit quality were studied in comparison to the control in the following season. We evaluated the effects of progesterone treatment on fruit quality parameters during storage at 6 ± 1 °C for up to four weeks, depending on CI, fruit firmness, electrolyte leakage, malondialdehyde content, total phenolic content, 2,2-diphenyl-1-picrylhydrazyl, trolox equivalent antioxidant capacity, PROG residue in mango mesocarp, proline, superoxide dismutase, catalase, glutathione reductase activity, lipoxygenase, assay of pectin-modifying enzymes activity (polygalacturonase, β-galactosidase, and pectin methylesterase), ATP, and ATPase activity. We also conducted a principal component analysis between these indicators. Our results indicate that progesterone treatment significantly reduced the incidence and severity of CI in mangoes, with the highest effect observed at a concentration of 12 µM. Under these conditions, mangoes exhibited lower CI, electrolyte leakage, malondialdehyde content, and lipoxygenase activity, in addition to higher firmness, and antioxidant activity, compared to the control samples. Overall, our findings demonstrate that progesterone treatment can effectively reduce CI and improve the quality and shelf life of mangoes during storage under low-temperature conditions.