Storage of ‘Cox Orange Pippin’ Apple Severely Affected by Watercore

Abstract

Watercore is a typical physiological disorder of apples and can normally induce the development of related internal disorders during storage. The aim of this study was to investigate the disappearance of watercore, the development of internal storage disorders (ISD) and the maintenance of quality traits of ‘Cox Orange Pippin’ apple during 6 months storage at 3 °C (±0.3 °C) under the following storage conditions: Regular air (RA); rapid storage at 1.5 kPa O2 plus 1.5 kPa CO2; 20 d pre-storage in air at 10 °C followed by storage at 1.5 kPa O2 plus 1.5 kPa CO2; 20 d delayed in the pull down of oxygen partial pressure (p) at 3 °C followed by storage at 1.5 kPa O2 plus 1.5 kPa CO2; and the rapid storage at 3.0 kPa O2 plus <0.2 kPa CO2. At storage end, watercore disappeared faster in RA-stored fruit; however, these fruit were softer, yellower and lower in acidity and showed the highest ISD index (40.0). The rapid storage under 1.5 kPa O2 plus 1.5 kPa CO2 resulted in fruit without ISD, higher firmness, higher acidity, greener skin colour, and a watercore index of 7.5 at storage end. Delayed CA-stored fruit did not keep satisfactory quality traits, and resulted in high watercore (7.6) and ISD indexes (6.9). A similar behaviour to the delayed CA-stored fruit, was observed in apple rapid stored at 3.0 kPa O2 plus <0.2 kPa CO2 and in fruit subjected to 20 d pre-storage in air at 10 °C. The fruit specific weight decreased from 0.89 at harvest time to 0.82 at storage end, but no significant differences were observed between treatments. A positive correlation (r = 0.91) was found between the fruit specific weight and the severity of watercore. In conclusion, the rapid storage of severe watercored ‘Cox Orange Pippin’ apple at 1.5 kPa O2 plus 1.5 kPa CO2 maintained higher firmness, higher acidity and greener skin colour, without occurrence of ISD after 6 months’ storage.