Alleviating chilling injury and maintaining quality of cold-stored zucchini fruit by utilizing modified atmosphere packaging, 1-methylcyclopropene, and pre-storage low humidity conditioning

Chilling injury (CI)-induced surface pitting (SP) presents a significant challenge in the storage of zucchini fruit. This study aimed to determine whether the slow-release 1-methylcyclopropene (1-MCP) or pre-storage low humidity conditioning (PLHC) could effectively delay the onset of SP and enhance the storage quality and antioxidant systems within polyethylene packaging (PEP)- and modified atmosphere packaging (MAP)-treated zucchini fruit. Results indicated that zucchini fruit without packaging exhibited a significantly high SP after 7 d of storage at 3 ± 0.5 °C. In contrast, zucchini treated with PEP and MAP remained free from SP for 7 and 14 d of storage, respectively. Moreover, MAP effectively suppressed SP development and decay over the whole 28-d storage period compared to the PEP treatment. This effect was linked to reduced O2 and increased CO2 levels, which mitigated weight loss and oxidative damage. Evidence for this included lower concentrations of malondialdehyde, superoxide anion, and hydrogen peroxide, alongside enhanced activities of antioxidant enzymes (i.e., peroxidase and catalase), and increased levels of antioxidants (i.e., ascorbic acid and glutathione). Applications of slow-release 1-MCP and PEP effectively reduced SP and oxidative stress. However, when combined with MAP, this treatment resulted in excessive physiological suppression, which accelerated the loss of firmness and decay. Treating with PLHC for 1 d significantly alleviated SP, particularly when combined with MAP, by boosting antioxidant defense and reducing weight loss (WL). In conclusion, the integration of PEP with slow-release 1-MCP, or the use of MAP alongside PLHC for 1 d, effectively mitigated CI in zucchini fruit.