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Abstract
There was a definite trend of increasing titratable acidity and decreasing soluble solids from the periphery of the segments toward the core in ‘Pineapple’ and ‘Valencia’ oranges and in ‘Marsh’ and ‘Duncan’ grapefruit. Soluble solids generally increased along the axis of the fruit from the stem regions toward the stylar end. Titratable acidity was higher at the central regions than at either end. Ratios of soluble solids to acid varied from 9.6 to 20.5 at different positions in ‘Valencia’ orange and from 5.5 to 12.5 in ‘Marsh’ grapefruit. Reducing sugars were lower and non-reducing sugars higher at the stem and stylar ends than at the central regions of both oranges and grapefruit. Ratios of nonreducing to reducing sugars decreased from both ends and from the periphery towards the central core. Total nitrogen and vitamin C were slightly higher in the stem halves than in the stylar halves and higher at the core than at the periphery.
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.