REDUCED INTERNAL BROWNING IN PINEAPPLE FRUIT BY 1-MCP PRETREATMENT AND THE ANTIOXIDANT RESPONSE

The objective of this study was to determine the involvement of 1-MCP on reducing internal browning and antioxidant systems in ‘Phulae’ pineapple fruit under chilling stress. Phulae pineapple at 25% yellow peel stage were pre-treated with different concentrations of 1-MCP (100, 200, and 400 nl L^-1) for 16 h, at 25°C, and non-treated fruit were used as the control. Fruit were packed in corrugated boxes and stored at 10°C, 90-95% RH, for 30 days. Internal browning symptoms were first observed in the control treatment after 20 days of storage, while pretreatment with 200 nl L^-1 of 1-MCP significantly reduced the percentage of internal browning in Phulae pineapple fruit. The changes of peel color and total soluble solid (TSS) was delayed by 1-MCP treatment. Hydrogen peroxide (H₂O₂), superoxide dismutase (SOD), and ascorbate peroxidase (APX) increased during storage and their changes were not significantly affected by different concentrations of 1-MCP treatment. The activity of catalase (CAT) was higher in 200 nl L^-1 of 1-MCP than other concentrations until 10 days of storage. Glutathione content was significantly higher in fruit pre-treated by 200 nl L^-1 of 1-MCP than in fruit pre-treated with other concentrations throughout storage. These results suggest that 200 nl L^-1 of 1-MCP could increase chilling resistance in Phulae pineapple fruit by regulating glutathione metabolism.