Effects of low-temperature conditioning on browning, reactive oxygen species metabolism, and quality attributes of “Dajixin” wampee ( <i>Clausena lansium</i> ) fruit during cold storage at 3 °C for 16 days

This study investigated the effects of three low-temperature conditioning (LTC) treatments on the storage quality and postharvest physiology of “Dajixin” wampee ( Clausena lansium ) fruit during cold storage at 3 °C for 16 days. Treatments included LTC 1 (12 °C, 4 d), LTC 2 (8 °C, 4 d), and LTC 3 (stepwise 12 °C for 2 d then 8 °C for 2 d). Compared with direct cold storage (control), LTC 2 reduced the browning index by 22.9% (from 3.80 to 2.93, P &lt; .05), suppressed weight loss (7.17% vs. 7.90%, P &lt; .05), and maintained higher total soluble solids (19.58% vs. 17.11%, P &lt; .05). LTC 2 inhibited malondialdehyde accumulation (6.37 vs. 7.52 µmol/g, P &lt; .05), enhanced superoxide dismutase and phenylalanine ammonia lyase activities, and suppressed peroxidase and polyphenol oxidase activities relative to the control. Furthermore, LTC 2 maintained higher total phenolic content (1.72 mg GAE/100 g FW at day 12) and DPPH radical scavenging activity (75.5% at day 12). Among the three protocols, LTC 2 (8 °C, 4 d) was the most effective in delaying postharvest senescence and reducing browning, providing a practical protocol for extending the shelf life of cold-sensitive wampee fruit.