Antioxidant contents and activity of 1-methylcyclopropene (1-MCP)-treated ‘Empire’ apples in air and controlled atmosphere storage

The effect of 1-MCP on ripening and concentrations of total phenolics, flavonoids, anthocyanins and total antioxidant activity of ‘Empire’ apples (Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.) was studied. Fruit were stored in air for up to 5 months, and in controlled atmosphere (CA) of 2 and 3 kPa O2 (2 kPa CO2) at 0.5 and 2.2 °C for 4.5 and 9 months. Ripening was delayed by 1-MCP treatment in both air and CA storage as indicated by lower internal ethylene concentrations and slower softening than in untreated fruit. Overall, total phenolic, flavonoid and anthocyanin concentrations as well as antioxidant activity were relatively stable during air and CA storage. In air-stored fruit, total phenolic concentrations were higher in the peel of 1-MCP treated fruit than in the control fruit, but slightly lower in the flesh of 1-MCP treated fruit. In CA-stored fruit, interactions between O2 partial pressures, temperature and storage duration were detected but overall, few consistent trends were observed. However, flavonoid concentrations were higher in the flesh of 1-MCP treated than untreated fruit kept in 2 kPa O2 while anthocyanin concentrations, only measured in the peel, were not affected by 1-MCP treatment. There were no correlations found between total phenolics and antioxidant activity. Ascorbic acid concentrations declined in both peel and flesh tissues of untreated and 1-MCP treated fruit stored in air, while changes of ascorbic acid concentrations in CA-stored fruit were inconsistent.