Carbon dioxide-enriched atmospheres during cold storage limit losses from Botrytis but accelerate rachis browning of 'Redglobe' table grapes

We evaluated a range of CO2 and O-2 concentrations as a potential substitute to SO2 treatments for controlling decay development on 'Redglobe' table grape during storage. During the 1998 season, early (14% soluble solids concentration, SSC) and late harvested (17% SSC) 'Redglobe' grapes were stored in 16 controlled atmospheres of 5, 10, 15, 20, and 25 kPa CO2 combined with 3, 6, and 12 kPa O-2. During the 1999 season, 10 or 15 kPa CO, combined with 3, 6, and 12 kPa O-2 were tested in comparison with air stored grapes as control. In the 2000 season, late harvested 'Redglobe' grapes were kept in 12 kPa CO2 + 6 kPa O-2 in comparison with standard commercial storage practices of SO, fumigation. None of the atmospheres tested for up to 12 weeks at 0 degreesC influenced SSC, titratable acidity (TA), SSC:TA, or berry shatter and browning. Rachis browning was accelerated and trained judges perceived 'off-flavor' in grapes exposed to CO2 levels above 10 and 15 kPa for early and late harvested 'Redglobe' grapes, respectively. Atmospheres including above 10 kPa CO2 controlled decay incidence and spread among berries (nesting) independent of O-2 concentrations during storage at I degreesC for up to 8 weeks and after 3 days at 20 degreesC, simulating a retail display period. Based on these data, a combination of 10 kPa CO, with 3, 6 or 12 kPa 02 is suggested for up to 12 weeks storage for late harvested 'Redglobe' grapes. An atmosphere of 10 kPa CO, + 6 kPa 02 is suggested for early harvested 'Redglobe' grapes, but not to exceed 4 weeks. (C) 2002 Elsevier Science B.V. All rights reserved.