Effects of 1-methylcyclopropene treatments on fruit quality attributes and cell wall metabolism in cold stored ‘summer prince’ and ‘summer king’ apples

This study was conducted to investigate the effects of different concentrations (0.5 and 1 µL·L^-1) and application times (0.5, 1, 0.5+0.5 and 1+1 µL·L^-1) of 1-methylcyclopropene (1-MCP, SmartFresh™) treatment on post-harvest quality and cell wall metabolism of ‘Summer Prince’ and ‘Summer King’ apple fruit during cold storage. Compared with control fruit, 1-MCP treatments maintained higher flesh firmness and titratable acidity in both apple cultivars. In contrast, the soluble solids content did not show differences in all treatments. The internal ethylene concentration was higher in control fruit, but fruit with 1-MCP treatments expressed lower ethylene concentration. Weight loss in ‘Summer Prince’ fruit treated with 1-MCP was lower than in control fruit during storage. The starch index did not show differences in all treatments; on the other hand, greasiness or other storage disorders were not detected during storage. Both cultivars showed higher contents of total sugar and uronic acid in both 1-MCP treatments than the control. ‘Summer Prince’ apple had increased cell wall degrading enzyme activity of β-Gal, α-Gal, β-Glc, α-Man, and α-Ara enzymes after 4 months of storage in control fruit. Likewise, ‘Summer King’ apple had increased activity of β-Gal, β-Glc, β-Xyl, and α-Ara enzymes after 2 months of storage in the control fruit. Both cultivars showed lower cell wall degrading enzyme activities in 1-MCP treatments than in the control. In conclusion, 1-MCP treatment of ‘Summer Prince’ and ‘Summer King’ apple fruit was effective in maintaining quality by inhibiting internal ethylene and cell wall metabolism. However, the different concentrations and repeated applications of 1-MCP treatment were not different in this study. Therefore, it was suggested that 0.5 µL·L^-1 1-MCP treatment could be considered an economically effective concentration for this study.