Fumigating Citrus with Phosphine Does Not Impact Marketability or Eating Quality

Abstract

To ensure control of arthropod pests, fresh citrus exports from the United States may be subject to postharvest phytosanitary treatment. Treatments, however, can potentially cause a phytotoxic response and damage the fruit. The main purpose of this study was to confirm that phosphine fumigation does not impact either the marketability or eating quality of citrus. Methyl bromide (MB) fumigation and cold treatment (CT) were included in the testing as comparisons. Treatments were conducted as if they were associated with an oceanic voyage of 28 days followed by 1 week at 10°C and then 1 week at 20°C to typify distribution and marketing conditions. Key quality parameters were evaluated, relative to nontreated controls, for each of three “predeparture” phosphine fumigations, an “on arrival” MB fumigation, and a 28-day CT at 1°C. The three phosphine treatments evaluated were 1.5 mg/liter for 12 h or 48 h at 5°C or for 48 h at 12°C. MB was applied at 64 mg/liter for 2 h at 5°C. In the second year, navel oranges were further evaluated using a sequential treatment in which a “predeparture” phosphine fumigation was followed by the “on arrival” MB fumigation. This work is the first to present results comparing phytosanitary treatments over multiple kinds of citrus and indicated that the phosphine treatments did not alter marketability or sensory quality for any of the citrus types. This contrasted with MB fumigation, which was damaging to the peel of all citrus, except Valencia oranges, and harmed grapefruit and mandarin flavor.