Interaction of 1-methylcyclopropene, temperature and dynamic controlled atmosphere by respiratory quotient on ‘Galaxy’ apples storage

Abstract

The 1-methylcyclopropene (1-MCP) is applied on apples under controlled atmosphere (CA) storage at more elevated temperatures (2.0 or 3.0 °C). The objective of this study was to evaluate if it is possible keep 'Galaxy' apples quality during storage at higher temperatures (2.0 or 2.5 °C, ± 0.1 °C) compared with 1.5 °C (±0.1 °C) using the dynamic controlled atmosphere method monitored by the respiratory quotient (DCA-RQ) without 1-MCP application. The treatments were: [1] CA; [2] DCA-RQ with respiratory quotient 1.3 (DCA-RQ1.3) and DCA-RQ1.5 with CO2 of 1.2 kPa. All treatments were with or without 0.625 μL L−1 of 1-MCP treatment during 24 h and stored under 1.5, 2.0 and 2.5 °C. Fruit stored in DCA-RQ had flesh firmness approximately 10 N higher than CA, without 1-MCP application. When 1-MCP was applied, flesh firmness remained the highest under DCA-RQ1.3 at the lowest temperature (1.5 °C). Ethylene production was higher in the CA condition (higher than 0.61 ng C2H4 kg−1 s−1) without 1-MCP application as compared to DCA-RQ1.3 and 1.5 at all three temperatures (less than 0.09 ng C2H4 kg−1 s−1). 'Galaxy' apples can be stored at more elevated temperatures (2.0 and 2.5 °C) under DCA-RQ1.3 and DCA-RQ1.5 without 1-MCP application, because of the lower mealiness, ethylene production, ACC oxidase and higher flesh firmness than at 1.5 °C.