Prediction of controlled atmosphere-induced flesh browning in 'Fuji' apple

Rapid induction of internal flesh browning by exposure of fruit to high CO2, fruit maturity indices, respiration rates and CO2 permeances were assessed as predictors of flesh browning which developed in apple (Malus domestica, Borkh, cv. Fuji) during long-term controlled atmosphere storage. Fruit were harvested from eight orchards at 170, 190 or 210 days after full bloom and held at 20 degrees C in 50 kPa CO2 (balance air) for 1-3 days, in 20 kPa CO2 (balance air) for 3-7 days or at 0 degrees C in a controlled atmosphere of 2 kPa O-2 + 2 kPa CO2 for 150 days. Flesh browning increased with greater exposure time in 20 kPa and 50 kPa CO2 and after 3 days of exposure, more browning developed in fruit exposed to 50 than 20 kPa CO2. Flesh browning in all atmospheres increased with harvest date but significant variability was present among orchards at any one harvest. Across all orchards and harvest dates, strong positive relationships were found between flesh browning after controlled atmosphere storage and that which developed after short-term exposure to 20 kPa CO2 at harvest. This relationship improved with decreasing exposure time at 20 kPa CO2. While substantial differences in fruit maturity indices (background colour, starch pattern index, watercore incidence, soluble solids concentration, titratable acidity, flesh firmness), fruit respiration rates and fruit permeances to CO2 determined at harvest were also found among harvest dates and orchards, they were at best poorly related to flesh browning. The best predictor of orchard and harvest date differences in controlled atmosphere-induced flesh browning was therefore assessment of flesh browning after exposure of fruit to 20 kPa CO2 for 3 days. (C) 1998 Elsevier Science B.V. All rights reserved.