Extremely low-oxygen storage: aerobic, anaerobic metabolism and overall quality of apples at two temperatures

The objective of this work was to evaluate the effect of extremely low-oxygen storage on the aerobic, anaerobic metabolism and overall quality maintenance of ‘Royal Gala’ and ‘Galaxy’ apples stored at two temperatures. For ‘Royal Gala’ apples, four treatments were evaluated in a two-factor scheme (2 × 2), with two storage conditions: [1] 1.2 kPa O₂ + 2 kPa CO₂; [2] 0.8 kPa O₂ + 1.6 kPa CO₂; and two temperatures (1.0 and 1.5 °C). For ‘Galaxy’ apples, the experiment was conducted in a two-factor (3 × 2) scheme with three storage conditions: [1] 1.2 kPa O₂ + 2 kPa CO₂; [2] 0.8 kPa O₂ + 1.6 kPa CO₂; [3] 0.4 kPa O₂ + 1.2 kPa CO₂, and two temperatures (1.0 and 1.5 °C). The ‘Royal Gala’ apples stored under 0.8 kPa O₂ + 1.6 kPa CO₂ at 1.5 °C had higher flesh firmness, healthy fruit and soluble solids along with lower incidence of flesh breakdown and mealiness. The ‘Galaxy’ apples stored under 0.4 kPa O₂ + 1.2 kPa CO₂, at temperature of 1.5 °C had lower 1-carboxylic acid-1-aminocyclopropane (ACC) oxidase enzyme activity, ethylene production, occurrence of mealiness, when compared to 1.0 °C. The storage of these two cultivars at 1.5 °C with extremely low O₂ partial pressures is possible. The possibility to increase the storage temperature from 1 °C, which is traditionally used for these mutants, to 1.5 °C allows to keep better quality with the advantage of energy saving.

Key words
controlled atmosphere; food preservation and safety; post harvest fruit; shelf life