Preharvest Sprayable 1-Methylcyclopropene (1-MCP) Effects on Fruit Quality Attributes and Cell Wall Metabolism in Cold Stored 'Fuji' Apples

This study was carried out to investigate the effects of a pre-harvest treatment with sprayable 1-methylcyclopropene (S1-MCP) on fruit quality and cell wall metabolism during cold storage of 'Fuji' apples (Malus domestica Borkh). Three different treatments, 95, 125, and 250 mg.L-1 S1 -MCP, applied at 1, 2, or 3 weeks before harvest, were used in this study. Fruit firmness of untreated fruit decreased from 62.3 Newton (N) at harvest to 55.3 N at 180 days after storage. However, a treatment with 250 mg.L-1 S1-MCP at 2 or 3 weeks before harvest maintained a high flesh firmness of 60 N even after 180 days of cold storage. The titratable acidity (TA) of untreated fruit decreased rapidly from 0.36% at harvest to 0.19% at 180 days after storage, but the 125 and 250 mg.L-1 Sl-MCP treatment at 2 weeks before storage maintained the TA at 0.32-0.33% after 180 days of cold storage. The internal ethylene concentration was significantly increased to 326.4 mu L.L-1 after 180 days of storage in untreated fruit, but it remained very low (17.3 and 32.4 mu L.L-1 ) after storage when fruit were treated with 250 mg.L-1 S1 -MCP at 2 and 3 weeks before harvest, respectively. The uronic acid content, which is a component of the cell wall middle lamella, in alcohol insoluble material (AIS) was higher (301.47 mu g.mg(-1). AIS(-1) ) in the S1 -MCP treated fruit after 180 days of storage compared to the untreated fruit (271.72 mu g.mg(-1). AIS(-1) ). The activities of alpha- and beta-galactosidase in cell wall hydrolases were significantly lower in Sl-MCP treated fruit than in the untreated fruit after 180 days of storage.