Oxidative behaviour of Blanquilla pears treated with 1-methylcyclopropene during cold storage

The increasing use of 1-methylcyclopropene (1-MCP) to extend the commercial life of fruit constitutes an attractive way of improving packing house competitiveness. This compound prevents the effects of ethylene in a wide range of fruit and vegetables. However, despite the extensive literature relating to this action on ethylene, little is known about its other physiological effects. In this work, pears (Pyrus malus L cv Blanquilla) were treated with 100 ppb 1-MCP immediately after harvest and stored in air for 5 months. Differences in oxidative stress and in antioxidant potential between controls and 1-MCP-treated fruits were established, determining the changes in the levels of hydrogen peroxide, ascorbate content and ionic leakage during storage. Activities of the H2O2-generating enzyme superoxide dismutase (EC 1.15.11) and the H2O2-scavenging enzymes catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11) and unspecific peroxidase (EC 1.11.1.7) were also determined. 1-MCP-treated fruits exhibited lower levels of hydrogen peroxide, ascorbate and lower ionic leakage during storage. In accordance with this result, 1-MCP-treated fruits also exhibited higher enzymatic antioxidant potential. These results challenge the hypothesis that the beneficial effects of 1-MCP on ripening were not exclusively due to its action on ethylene but also to an increase in antioxidant potential in pear