Antioxidative enzyme activity and internal browning of 1-methylcyclopropene- treated European pear fruits (cv. 'Shahmiveh' and 'Sebri')

The effects of 1-methylcyclopropene (1-MCP) on antioxidative enzyme and internal browning (IB) incidence of two European pear cultivars Shahmiveh' and Sebri' stored at 0.5 degrees C were investigated. Ethylene production of Sebri' was delayed by 1-MCP but suppressed in Shahmiveh'. IB increased in both cultivars, with a higher level of the incidence in Shahmiveh', and was reduced by 1-MCP. Activities of catalase (CAT) and peroxidase, but not superoxide dismutase (SOD), decreased in untreated fruit during the first 40days. 1-MCP had little effect on SOD activity or on total phenolics. Polyphenoloxidase activity did not increase over time in 1-MCP-treated fruit of the IB sensitive Shahmiveh', and the effect was inconsistent for Sebri'. Ascorbic acid (AA) levels in 1-MCP-treated fruit of both cultivars declined at a lower rate compared with untreated fruit during storage, but the reduction in AA levels was faster in Shahmiveh' compared with Sebri'. Also, the effects of 1-MCP on antioxidative systems may be related to IB development.