Influence of temperature, CA conditions and relative humidity on physiological disorders of 'fuji' apples

In some years 'Fuji' apples develop internal flesh browning during controlled atmosphere storage, and frequently show scald after long-term storage. In order to evaluate the effect of storage temperature, relative humidity and concentrations of CO2 and O-2 On huh quality, especially flesh browning and scald, two experiments were conducted. 'Fuji' apples from a commercial orchard were stored in small controlled-atmosphere (CA) chambers with a return-now closed system for nine months, followed by a seven-day shelf lifeperiod. In the first experiment using 0 degrees C or 1 degrees C in CA of 0.5%CO2/1.5%O-2, fruits were exposed to a higher temperature (2.5 degrees C) during the first two months, plus high relative humidity (97%) and low relative humidity (92%). In the second experiment, fruits were stored at 1 degrees C in ultra-low oxygen (ULO) conditions (0.7% O-2) during the first two months of storage, and high CO2 concentrations (4% CO2) during the first or last two months of storage. During the remaining time fruits were stored in CA of 0.5% CO2/1.5% O-2. Results indicate that fruits stored at ODC had higher firmness, acidity and weight loss and lower scald incidence in comparison with storage at 1 degrees C. Exposure at the beginning of storage to high temperature (2.5 degrees C) combined with low humidity totally eliminated flesh browning, but high temperature or low humidity alone had no effect on the disorder. ULO conditions during first two storage months increased scald and Penicillium rot. High CO2 concentration (4%) during the first or last two months increased internal browning and had no effect on other quality parameters. This suggests that 'Fuji' apples in Brazil have to be stored under low CO2 concentrations during the full storage period.