Market Life Extension and Fruit Quality Enhancement of Navel Oranges

Louisiana-grown Navel oranges are a highly popular fruit in the late fall and early winter in local markets. However, the marketing period is limited due to insufficient refrigerated storage and inadequate postharvest care practices followed by the majority of small-scale citrus producers. Tests were conducted to determine the effect of postharvest temperature management and value-added packaging on market life and quality of ’Washington’ Navel oranges. Fruit were individually shrink-wrapped in polyolefin film and stored at 4° and 21° C. The market life of unwrapped fruit held at 21° C, 40 % relative humidity, was 3 weeks, with a weight loss of 22.0%. The market life of unwrapped fruit held at 4° C was extended to 14 weeks, with a weight loss of 19.6%. In contrast, shrink-wrapping extended the market life of Navel orange fruit held at 21° C for up to 16 weeks, with a final average weight loss of 5.0%. A maximum market life of 20 weeks was obtained from the shrink-wrapped fruit held at 4° C, with a final weight loss of only 1.4%. The appearance and overall eating quality of the shrink-wrapped fruit was better than the unwrapped controls. The fruit sugar:acid ratio significantly increased during storage, primarily due to a decrease in % acidity. Sucrose constituted the major sugar in Navel orange fruit, followed by fructose and slightly lesser amounts of glucose. The total sugar content and sucrose content was slightly higher in wrapped fruit than unwrapped fruit after storage. Citric acid was the dominant organic acid in the Navel oranges, typically comprising over 80% of the total organic acid content. Malic and succinic acids, present in similar concentrations, constituted the other principal organic acids. The content of all three organic acids decreased during storage, with greater losses occurring at the higher storage temperature.