Diphenyl Residues in Florida Grapefruit and Oranges Following Actual and Simulated Long Export Shipments1

Abstract

Abstract The long voyage of Florida grapefruit (Citrus paradisi Macf.) to Japan and extended marketing periods on arrival were associated with a problem with excess diphenyl (biphenyl) residues. Japanese food additive regulations have necessitated reliance on the vapor-phase fungistat diphenyl, for which residues in the fruit increase with time after packing. Residues in some shipments unexpectedly exceeded the Japanese tolerance of 70 ppm. Experiments designed to identify the effect of various factors on diphenyl residues are reported. The amount of diphenyl, temperature before refrigerated transit and exposure time, especially before refrigeration, affected diphenyl residues. Air filtration had little effect. Very early season grapefruit (harvest started before legal maturity) in August and September 1978 absorbed excessive diphenyl residues. Excessive absorption of diphenyl by grapefruit is apparently characteristic of very early fruit.