The efficacy of soaking fresh-cut nectarines in melatonin concentrations and its effect on antioxidant capacity microbial content and storage quality

The study aimed to identify the optimal concentration of exogenous melatonin for fresh-cut nectarines by evaluating their quality attributes during storage at 0 °C with relative humidity (RH) of 85 % - 90 % after treatments with different concentrations (0 mM, 0.05 mM, 0.1 mM, and 0.5 mM, with 0 mM as the control). Furthermore, the optimal melatonin treatment concentration and control were used to analyze its effects on antioxidant capacity and tissue microstructure of fresh-cut nectarines. The results indicated that 0.1 mM melatonin was the most effective treatment concentration for maintaining the primary physicochemical qualities of the fresh-cut nectarines. On 12 d of the storage, the 0.1 mM melatonin-treated group showed significant increases of 4.09 % in total phenolic content and 5.78 % in ascorbic acid compared to the control group, with more retained tissue microstructure. Additionally, the treatment was observed with a reduction of 23.82 % in MDA content, 39.31 % in H2O2 content, and 34.26 % in superoxide anion levels, compared with the control. Moreover, the melatonin treatment inhibited the microbial growth and enhanced the antioxidant capacity of fresh-cut nectarines. Furthermore, 0.1 mM melatonin treatment reduced the gene expression and activity of POD and PPO enzymes, while increased the gene expression and activity of PAL and CHS enzymes. These findings demonstrate that 0.1 mM melatonin not only delays browning in fresh-cut nectarines but also improves their antioxidant capacity and storage quality, highlighting its potential as an effective post-harvest treatment strategy for reducing the reliance on synthetic preservatives in commercial applications.