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.

Key words
anaerobic metabolism; ethyl acetate; ethylene; Malus domestica; physiological disorders