OBJECTIVE MEASURES OF CHILLING INJURY IN GRAPEFRUIT

Abstract

Storage of `Marsh' white seedless grapefruit (Citrus paradisi Macf.) for 2 weeks at 5C resulted in the development of chilling injury (CI). Electrolyte leakage from chilled fruit did not increase significantly until CI had become severe, and was therefore considered to be a poor index of CI. In contrast to electrolyte leakage, respiration and ethylene evolution were consistently higher in chilled than in nonchilled fruit, even prior to the onset of visual symptoms of CI. Respiratory rates ranged from 8.0 to 10.7 and 4.6 to 6.7 ml/kg/hr in chilled and nonchilled fruit, respectively. Ethylene evolution was not detected from nonchilled fruit, whereas chilled fruit produced from 45.6 to 249.3 ml/kg/hr ethylene. Ethylene production was maximum following 2 weeks at 5C. Results of this study indicate that increases in electrolyte leakage do not occur until considerable tissue damage has occurred, whereas stimulation of respiration and ethylene evolution occur early in the development of CI.