科研之友
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摘要
Preclimacteric avocado (Persea americana Mill. cv. Booth 7) fruit were treated with aqueous 1-methylcyclopropene (1-MCP) at 0.93 and 9.3 mmol m(-3) and then stored at 20 degrees C to investigate the effect of 1-MCP on antioxidant systems of mesocarp tissue during ripening. Exposure to 1-MCP concentrations significantly delayed softening and peak ethylene production. 1-MCP significantly delayed accumulation of total soluble phenolics, flavonoids, and total antioxidant capacity although levels eventually reached control fruit maxima. The influence of 1-MCP was more pronounced at the higher concentration. Activities of peroxidase [POD (EC 1.11.1.7)], superoxide dismutase [SOD (EC 1.15.1.1)], catalase [CAT (1.11.1.6)] and L-ascorbate peroxidase [APX (EC 1.11.1.11)] increased during early ripening of control fruit followed by slight (CAT) or significant (POD, APX) declines with further ripening. Increases in activities of all enzymes were delayed in proportion to 1-MCP concentration, and maximum activities attained during ripening were largely unaffected by 1-MCP. Postclimacteric declines in POD and APX were not observed at the higher 1-MCP concentration, possibly reflecting incomplete ripening. The results indicate that changes in antioxidant parameters of avocado fruit are not markedly influenced by 1-MCP but are delayed or altered in proportion to the general suppression of ripening as indicated by ethylene production and fruit softening trends. Together with previously published reports, the data also indicate that the effects of ethylene-action suppression on antioxidant parameters during ripening vary considerably among different fruits. Relationships between antioxidant systems, ethylene and ripening are discussed.
