DYNAMIC CA STORAGE OF ORGANIC APPLE CULTIVARS

Two new tools for improved preservation of apple quality have been developed in recent years: the treatment of apples with 1-MCP (trade name SmartFresh™) and the dynamic controlled atmosphere storage (DCA). Because of the nature of the treatment, 1-MCP may not be applied for organically grown apples, whereas DCA may be used for organic fruit. Over three years, selected hot-water treated and non-treated organic apple cultivars (‘Topaz’, ‘Ariane’, ‘Otava’) were stored under DCA-conditions in order to examine whether hot water treatment has an impact on fruit stress during DCA-storage and if DCA-stored fruit retain quality better than ULO-stored fruit during long-term storage. Furthermore, organic fruit were compared to fruit produced under “integrated production” conditions (IP). The critical oxygen concentration (anaerobic compensation point, ACP) during DCA-storage was not influenced by previous hot-water treatment nor by the production method. However, ACP varied from year to year (e.g., for ‘Topaz’ 0.20, 0.18 and 0.56 kPa O₂ over 3 years), showing that yearly fluctuations of climatic conditions during production may influence fruit behaviour during storage. For ‘Topaz’ and ‘Otava’, DCA had no positive effect on fruit quality compared to ULO conditions, whereas for ‘Ariane’, DCA stored fruit retained fruit firmness and acidity better compared to fruit stored under ULO conditions. Hot-water treatment did not affect fruit quality and the incidence of physiological disorders of DCA-stored apple. Fruit rot was affected by the cultivar, ‘Topaz’ being the most susceptible cultivar and ‘Ariane’ the most resistant to fruit rot. Organic fruit were susceptible to higher fruit rot during DCA-storage than IP fruit. Compared to ULO conditions, DCA did not reduce fruit rot.