Extremely low oxygen partial pressures for the storage of ‘Royal Gala’ apple

ABSTRACT The aim of this study was to evaluate the effect of storing ‘Royal Gala’ apple under extremely low oxygen partial pressures on their anaerobic metabolism, ethylene production and fruit quality after 9 months of storage plus 7 days of shelf life at 20 °C. The storage conditions tested were: 1.2 kPa O2 + 2.0 kPa CO2; 0.7 kPa O2 + 1.5 kPa CO2; 0.5 kPa O2 + 1.2 kPa CO2; 0.4 kPa O2 +1.2 kPa CO2 and 0.25 kPa O2 + 0.0 kPa CO2. The fruit storage temperature was 1.0 °C (± 0.1). Fruit stored at 0.4 kPa O2 + 1.2 kPa CO2 maintained higher flesh firmness and a higher percentage of healthy fruit. The fruit stored under the 0.25 kPa O2 + 0.0 kPa CO2 condition had lower flesh firmness as well as a reduced percentage of healthy fruit and a high production of anaerobic metabolism compounds, such as ethanol and ethyl acetate, which may have caused fruit quality loss. The storage of ‘Royal Gala’ apple under 0.4 kPa O2 + 1.2 kPa CO2 is a technique that can be commercially applied to keep a better fruit quality after a 9 months storage period.摘要 本研究旨在探究极低氧分压（extremely low oxygen partial pressures）条件下储存‘皇家嘎啦’(Royal Gala)苹果，对其经过9个月储存并于20℃下进行7天货架期存放后的无氧代谢（anaerobic metabolism）、乙烯生成量（ethylene production）及果实品质的影响。本试验测试的储存条件如下：1.2 kPa O₂ + 2.0 kPa CO₂；0.7 kPa O₂ + 1.5 kPa CO₂；0.5 kPa O₂ + 1.2 kPa CO₂；0.4 kPa O₂ + 1.2 kPa CO₂；0.25 kPa O₂ + 0.0 kPa CO₂。果实储存温度为1.0℃（±0.1℃）。结果表明，采用0.4 kPa O₂ + 1.2 kPa CO₂条件储存的果实，可维持较高的果肉硬度（flesh firmness）与健康果实占比。而在0.25 kPa O₂ + 0.0 kPa CO₂条件下储存的果实，果肉硬度更低，健康果实占比下降，且会大量生成乙醇、乙酸乙酯（ethyl acetate）等无氧代谢产物，该类产物可能引发果实品质劣变。综上，采用0.4 kPa O₂ + 1.2 kPa CO₂的条件储存‘皇家嘎啦’苹果，可在9个月储存期后仍保持较佳果实品质，具备商业化应用潜力。