Delaying establishment of controlled atmosphere or CO2 exposure reduces 'Fuji' apple CO2 injury without excessive fruit quality loss

Storage of 'Fuji' apple fruit in a high CO2 (3 kPa) and low O-2 (1.5 kPa) controlled atmosphere (CA) reduced firmness and titratable acidity (TA) loss during long term storage. This CA environment also induced development of internal CO2-injury (brown-heart) and slowed the disappearance of watercore. The symptoms of internal CO2-injury were first detected 15 days after CA establishment and the severity increased during the first 4 months of CA-storage. Delaying establishment of CA conditions for 2-12 weeks significantly reduced the severity of CO2-injury. Delaying CO2 accumulation to 3 kPa for 1-4 months during CA (1.5 kPa O-2 + 0.05 kPa CO2) storage also reduced development of CO2-injury symptoms. Delaying CA or CO2 accumulation resulted in lower firmness and TA compared to establishment of CA within 72 h of harvest. However, the delay treatments did result in firmness and TA that were significantly higher compared to values for fruit stored in air. The incidence and severity of senescent injuries (flesh browning and core flush) detected during the late period of storage were greater in air- than CA-stored fruit. The results indicate the susceptibility of 'Fuji' apples to CO2-injury is highest during the first weeks of storage after harvest. Delaying establishment of CA or exposure to elevated CO2 after harvest may be a practical strategy to reduce CO2-injury while maintaining other important quality attributes at acceptable levels. (C) 2000 Published by Elsevier Science B.V.