Effect of 1-methylcyclopropene and modified atmosphere packaging on chilling injury and antioxidative defensive mechanism of sweet pepper
Some sweet peppers (Capsicum annuum L.) are chilling sensitive and can develop injury when stored at temperatures less than 7°C. This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP) (650 ppb) and modified atmosphere packaging (MAP) on chilling injuries (CI) of sweet pepper during 30 days storage at 4°C. The results showed that, 1-MCP and MAP reduced chilling injury symptoms which were correlated with decreased electrolyte leakage and malondialdehyde content. The combination of 1-MCP and MAP further reduced chilling injury. Atomic force microscope (AFM) images showed that, the surface of the sweet peppers with 1-MCP and MAP treatments were smoother than of the control samples. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) of sweet peppers were also influenced by 1-MCP and MAP. SOD, CAT and POD activities of sweet peppers were 87.3, 28.97 and 0.248 U·g-1, respectively at the beginning of the storage. The activities decreased during the first 15 days of storage followed by an increase during the later period of storage. Treatment with 1-MCP, MAP alone and in combination frequently reduced the activities of those enzymes during storage. These results suggested that, combination of 1-MCP treatment and MAP is a promising treatment for reducing chilling injuries of peppers stored at 4°C.
Key words: 1-MCP, chilling injuries, modified atmosphere packaging, sweet pepper.