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
