The effect of cold disinfestation treatment on the quality of Washington navel oranges in Sunraysia

Abstract

Trials over 2 years were undertaken to determine the effect of cold disinfestation at 1¦C on the internal and external quality of Washington navel oranges. Chilling injury in the form of cold scald and rind pitting were significantly increased by cold disinfestation. The incidence and severity of chilling injury was low (maximum 7% of fruit rejected due to chilling injury), indicating that 16 days storage at 1¦C will result in minimal fruit loss due to chilling injury. Extended storage at 10¦C after cold disinfestation at 1¦C for 16 days increased the severity of the chilling injury symptoms observed. The incidence of postharvest fungal breakdown was high in the second year of the trial and red Altemaria spot was high in the first year. Oleocellosis was present in almost all fruit tested and severe in 75% of the fruit. The overall external quality of the fruit was highly influenced by grower but no correlation between fruit quality and specific management practices could be made. These results indicate that 'in transit' cold disinfestation would be a feasible treatment for export Washington navel oranges but with provisos: that total transit time is kept to a minimum, and that care is taken to minimise postharvest fungal breakdown and incidence of oleocellosis.