Antioxidant properties of two apple cultivars during long-term storage

The antioxidant capacity was determined in the peel of two apple cultivars (Jonagold and Sʹampion) stored for 120 days at 1 °C, either in the regular cold chamber or in CA (2% CO2/2% O2). During long-term cold storage as well as during an additional 7 day storage of fruits at 16 °C, total phenols, total antioxidant activity (TAA), and radical scavenging activity (RSA) increased considerably, irrespective of the storage conditions. A slight decrease in anthocyanins was observed in apples stored in air, while the CA treatment did not cause any significant changes. Increase of soluble peroxidase (POD) activity was much stronger in apples kept in air than in CA, while, after a subsequent 7 day storage at high temperature, a further increase in enzyme activity was observed in all treatments. The high activity of polyphenoloxidase (PPO), determined in freshly harvested fruits, dropped to low (Jonadgold) or undetectable (Sʹampion) levels after cold storage, both in the regular chamber and in CA, and increased slightly after the high temperature treatment. In the stored fruits a marked ethylene evolution was found, especially when stored in air.