Optimization of progesterone treatment via response surface methodology to maintain quality and mitigate chilling injury in <i>Prunus persica</i> L.

ABSTRACT Peach fruit is susceptible to deterioration, such as browning, highlighting the importance of applying effective preservation treatments to maintain quality. This study investigated the effect of progesterone (PRG) on the storability of mature peach fruit (cv. ‘Early Swelling’). In the initial experiment, response surface methodology (RSM) was applied to evaluate key quality indicators, including browning, firmness, proline, and gamma‐aminobutyric acid (GABA) content to determine the optimal PRG concentration (1–30 µM) and treatment duration (1–30 min). Based on the RSM findings, a second experiment was applied using either 10 or 15 µM PRG for 10 min, selected as optimal conditions, compared with untreated controls. The peach fruits were stored at 2°C with 90–95% RH for 32 days. The findings demonstrated that all PRG treatments efficiently preserved fruit quality and prolonged storability relative to the control. PRG treatment at 15 µM showed superior efficacy, significantly reducing browning, malondialdehyde, and weight loss while sustaining total phenolics, firmness, and DPPH radical scavenging activity. Moreover, PRG treatments enhanced pectin methylesterase activity, proline levels, and GABA content. These outcomes suggest that PRG application is a promising approach for improving peach fruit storability, minimising postharvest deterioration, and maintaining quality during extended storage.