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 H 2 O 2 -generating enzyme superoxide dismutase (EC 1.15.11) and the H 2 O 2 -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.

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In order to determine the effects that 1-methylcyclopropene (1-MCP) may have on antioxidant metabolism during cold storage, apples (Malus ×domestica Borkh. cv. Golden Smoothee) were treated with 625 nL·L−1 1-MCP immediately after harvest and stored in air for 3 months. Differences in total antioxidant activity and ascorbate levels were determined during storage and related to the activity of the antioxidant enzymes superoxide dismutase [SOD (EC 1.15.1.1)], catalase [CAT (EC 1.11.1.6)], and peroxidase [POX (EC 1.11.1.7)] in pulp. The level of oxidative stress in the pulp tissue was also established by determining changes in levels of hydrogen peroxide and in the content of peroxidative markers during storage. Controls and 1-MCP-treated fruit exhibited similar changes in total antioxidant activity and ascorbate levels. However, significant differences in oxidative stress levels were found between treated and untreated fruit. 1-MCP-treated fruit exhibited lower levels of hydrogen peroxide and significantly lower levels in peroxidative markers, especially at the end of the storage period. In line with this last result, 1-MCP-treated fruit also exhibited greater enzymatic antioxidant potential and, more specifically, a higher level of POX activity. Collectively, these results showed that 1-MCP did not detrimentally affect the antioxidant potential of the fruit and provided evidence to support the hypothesis that the beneficial effects of 1-MCP on ripening are not exclusively limited to its effect on ethylene, but also include direct effects on peroxidation and POX enzyme activity.

Our results indicated that DSB and superficial scald are two different disorders involving different oxidative processes. DSB can be prevented by progressive cooling and selection of russeting-resistant clones.