; Watkins and Nock, 2012 ). These results are consistent with slower fruit ripening reflected in lower IEC or ethylene production and lower respiration rate. In a number of instances, rapid CA with or without previous 1-MCP treatment enhanced this fruit
James P. Mattheis, David R. Rudell, and Ines Hanrahan
F. W. Liu
A high CO2 slow cooling CA storage procedure was developed for `McIntosh' apples (Malus domestica Borkh.). The apples were cooled from 18° to 3°C in 15 days in atmospheres containing a constant O2 at 2.5% and decreasing CO2 starting with 12% and ending at 3%. The results of several tests in a flow-through simulated CA storage system revealed that the new procedure was nearly as effective as rapid CA and was much more effective than traditional slow CA in preserving the firmness of `McIntosh' apples for up to 4 months of storage. Maintaining a constant CO2 either at 12% or 3% instead of gradually decreasing it from 12% to 3% during the slow cooling period resulted in more storage disorders or/and softer apples.
Christopher B. Watkins and Kenneth J. Silsby
Occasional occurrence of a superficial skin injury associated with CA storage can cause severe commercial loss in the `Empire' cultivar in the northeast. To develop industry strategies to prevent losses due to the disorder, we have examined a number of factors related to its occurrence. 1) Fruit from six orchards were stored with 2% or 5% CO2 (with 2% O2) at 0.5 or 3°C for 6 or 9 months. Orchard variation in susceptibility was high. Preharvest factors such as maturity or mineral levels in the fruit did not account for these differences. Incidence of the disorder was much higher at 5% than at 2% CO2. However, temperature did not affect the extent of injury. 2) Exposure of fruit stored at 2% CO2/2% O2 to 5% CO2 at 4-week intervals from harvest until 20 weeks indicated that fruit were most susceptible to injury between 0 and 8 weeks. 3) A postharvest treatment with diphenylamine (DPA) prevented occurrence of the disorder, ethanol reduced it, but ascorbic acid had little effect. 4) Fruit were held at storage temperatures for up to 10 days before exposure to either 2% or 5% CO2. Injury was highest in fruit exposed one day after harvest and negligible when exposed after 10 days. Collectively the results indicate that rapid CA can aggravate the disorder if care is not taken to maintain low CO2 concentrations in the storage atmosphere but that use of DPA for control of superficial scald will prevent its occurrence.
Chris B. Watkins* and Jacqueline F. Nock
Most information about the effects of 1-methylcyclopropene (1-MCP) on apple fruit that is available in the literature involves its application immediately after harvest. However, depending on the storage facility, fruit may be treated within a few days of harvest, especially if destined for rapid CA storage, or after longer time periods. We have investigated the effects of: 1) 1, 2, 3, 4, 6, and 8 d delays before 1-MCP treatment on `McIntosh', `Cortland', `Jonagold', `Empire' and `Delicious' apple quality stored in air for 2 and 4 months, and in CA for 4 and 8 months; and 2) 1, 7, 14, and 21 d delays on `Cortland', `Jonagold', `Empire' and `Delicious' apple quality stored in CA for 5 months. `McIntosh' and `Empire' apples were harvested at two maturities. Our data show that responses of apple cultivars to 1-MCP can be affected by delay treatments, but that within each cultivar, these effects vary according to harvest maturity, storage type, and length of storage.