Controlled Atmosphere and Dynamic CA-Chlorophyll Fluorescence Storage of 'McIntosh' and 'Delicious'

Fruit from four orchards of ‘Delicious’ from western NY and ‘McIntosh’ from the Champlain region of NY were harvested, untreated or treated with 1-methylcyclopropene (1-MCP) and kept in controlled atmosphere (CA) and dynamic CA-chlorophyll fluorescence (DCA-CF) storage for up to 8 months.  O₂ levels for ‘Delicious’ were kept 0.2% above the fluorescence-derived low oxygen limit levels detected at 0.4% (0.5 ^oC) and 0.9% for ‘McIntosh’ (2 ^oC).  ‘Delicious’ apples had 0 to 90% water core at harvest.  After 4 months in storage, there was slightly higher firmness in the latter if fruit were not treated with 1-MCP, but otherwise few differences between CA and DCA-CF-stored fruit.  Water core was present in fruit from two orchards that had water core at harvest, and at higher levels in DCA-CF-stored samples, although much lower than at harvest.  After 8 months, DCA-CF ‘Delicious’ had less flesh browning than those in CA storage.  Firmness was slightly lower in two of the orchards in CA; this was not observed, however, in fruit stored in DCA-CF or treated with 1-MCP.  DCA-CF-stored ‘McIntosh’ had fewer disorders and were more firm after 4 storage months compared with those in CA conditions.  Vascular and core browning developed by 8 months, and were observed at similar levels in both CA and DCA-CF environments.  Lowest incidences of internal and external CO₂ injury occurred in DCA-CF-stored ‘McIntosh’.  The DCA-CF treatment often reduced senescent breakdown in the absence of 1-MCP, but in one orchard it was worse in DCA-CF than in CA, 1-MCP had a greater effect on firmness and quality while DCA-CF reduced certain disorders.  For both cultivars, a combination of DCA-CF and 1-MCP often resulted in the greatest number of high quality fruit.