HAYWARD AND EDWARDS: DIPHENYL RESIDUES 315 Using a drum dryer, temperatures as high as ing the adaptation and use of the double-drum 70° C can be used for densifying orange and dryer. grapefruit powders without discoloration. Mono- glyceride derivatives are effective as release LITERATURE CITED agents during the densifying operation. Recon- 1. Berry, R. E., O. W. Bissett, C. J. Wagner, Jr., and stitution time is increased somewhat by the densi M. K. Veldhuis 1964. Foam-mat dried grapefruit powders. Food Technol. In press. fying operation. 2. Bissett, O. W., J. H. Tatum, C. J. Wagner, Jr., M. K. Veldhuis, R. P. Graham and A. I. Morgan, Jr. 1963. Foam-mat dried orange juice. I. Time-temperature drying studies. Food Technol. 17:92-95. Acknowledgment 3. Graham, R. P., M. R. Hart and A. I. Morgan, Jr. 1964. Foam-mat drying citrus juices. Abstracts of 24th An The authors would like to thank Dr. A. I. nual Meeting of Institute of Food Technologists, No. 29. 4. Graham, R. P., L. F. Ginnette and A. I. Morgan, Jr. Morgan, Jr., and Mr. R. P. Graham of the West 1963. U. S. Patent No. 3,093,488 Preparation of stable de hydrated products. ern Regional Research Laboratory, Albany, Cali 6. Lawler, Frank K. 1962. Foam-mat drying goes to fornia, for their advice and suggestions concern work. Food Eng. 34:68-69. 6. Sjogren, C. N. 1962. Practical facts of foam-mat. Food Eng. 34:44-47. SOME FACTORS AFFECTING THE LEVEL AND PERSISTENCE OF DIPHENYL RESIDUES IN CITRUS FRUITS F. W. Hayward and G. J. Edwards Experimental Methods Florida Citrus Experiment Station Fruit.—The citrus fruits for these experi ments came from the groves of the Citrus Ex Lake Alfred periment Station. Two series of experiments The legal tolerance of 110 ppm for diphenyl were made using five citrus varieties; Hamlin in oranges, lemons, and grapefruit (6) was ex and Valencia oranges, Duncan and Marsh grape tended by the U. S. Food and Drug Administra fruit and Dancy tangerines. tion in 1960 to all citrus fruits (7). Previous Packinghouse Treatments.—All fruit were work at this Station (2) indicated that prolonged washed, dried, and coated with "Flavorseal 93" storage at high temperatures might produce before packing except for certain samples that residues of diphenyl in excess of the legal tol were packed without waxing. erance in tangerines and a few other citrus va Packing.—All fruit were packed in standard rieties. Since the packer has no control over four-fifths bushel telescope cartons with hand time and temperature of storage after the fruit holes. The diphenyl pads used each contained is shipped, methods of limiting diphenyl residues 2.35 grams of diphenyl. other than by regulating holding conditions are Series A.—This comprised five single-carton required. treatments of each of the five varieties, diphenyl Rygg et al. (4) found that lemons, placed in treatments being: open trays, lost diphenyl quite rapidly while other citrus fruits lost it more slowly (5). Grier- 1. Control —no diphenyl pad. son et al. (1) found that decay of Dowicooled 2. One-half diphenyl pad in bottom. oranges was controlled by the residual effects of 3. One-half pad on top and one-half pad in previous diphenyl treatment after the fruit was bottom. removed from the diphenyl pads to open crates. 4. One-half pad on top and one full pad in These experiments were designed to determine bottom. to what extent the diphenyl residue levels in 5. One pad on top and one pad in bottom. citrus fruits could be controlled by regulating the Series B.—This series compared waxed and number of pads used in each carton. Studies unwaxed fruit with replicated samples of a single were also made of the effects of a solvent-type diphenyl treatment. Single carton treatments protective coating on the absorption and reten were as follows: tion of diphenyl by citrus fruits. 1. Unwaxed—control—no diphenyl pads. 2. Unwaxed—one diphenyl pad on top and Florida Agricultural Experiment Stations Journal Series No. 1978. one in bottom. 316 FLORIDA STATE HORTICULTURAL SOCIETY, 1964 3. Unwaxed—one diphenyl pad on top and et al. (3). Results were calculated as ppm of one in bottom. diphenyl on the basis of the fresh weight of the 4. Waxed—control—no diphenyl pads. whole fruit. 5. Waxed—one diphenyl pad on top and one in bottom. Results and Discussion 6. Waxed—one diphenyl pad on top and one in bottom. Average results for diphenyl residues in or Storage.—Samples in the A Series were stored anges, grapefruit, and tangerines packed with at 70° F for 3 weeks. Samples in the B Series different numbers of diphenyl pads per carton were stored at 70° F for 5 weeks. Samples 2 and and stored for 3 weeks at 70° F are shown in 5, representing waxed and unwaxed fruit treated Figure 1. Residue levels increased as the num with diphenyl, were removed from the cartons ber of diphenyl pads per carton were increased. after 2 weeks and placed in open field crates Tangerines had a high level of diphenyl residues without diphenyl pads to determine the per and grapefruit a low level while oranges showed sistence of the diphenyl in the fruit and its effects intermediate values. From this, it appears that on keeping quality during the remaining 3 weeks residues of diphenyl can be controlled by limiting of the experiment. the number of diphenyl pads used in each carton. Figure 2 shows the average percentage total Keeping Quality.—All samples were examined decay in relation to the number of diphenyl pads for decay due to stem-end rot and penicillium used per carton of oranges, grapefruit, and tan mold at weekly intervals for the duration of the gerines after storage for 3 weeks at 70° F. Half experiments. of a diphenyl pad per carton was too little to Diphenyl Residues.—At weekly intervals reduce decay but one pad, used half in the bot throughout the experiments, two fruit were taken tom and half on top, gave a considerable reduc from each sample carton and diphenyl residues tion in decay for oranges and grapefruit. For determined by the infrared method of Newhall tangerines, at least one and one-half pads were required but even the commonly used two-pad application was not very effective in controlling TANGERINES 80r decay under these experimental conditions. Al though telescope cartons are commonly used for oranges and grapefruit and are quite satisfac tory, these cartons are not often used for tanger- 60 30 a' CL 40 ORANGES u20 UJ o 10 GRAPEFRUIT 0.5 I 1.5 0 05 I 1.5 2 NUMBER OF PADS NUMBER OF PADS Figure 1.—Effects of the number of diphenyl pads packed Figure 2.—Effects of the number of diphenyl pads packed in cartons with grapefruit, oranges, and tangerines on the in cartons with grapefruit, oranges, and tangerines on the diphenyl residues in the fruit after 3 weeks at 70°F. percent total decay of the fruit after 3 weeks at 70° F. HAYWARD AND EDWARDS: DIPHENYL RESIDUES 317 ines as they keep better when containers having of the effects of wax on the absorption and re greater ventilation are used. tention of diphenyl. All samples which had been Although experiments were conducted with treated with diphenyl showed reduced decay five citrus varieties to determine the effects of throughout the entire holding period. There were wax on absorption and retention of diphenyl, no consistent differences between decay of waxed only the results on oranges are reported in detail. and unwaxed fruit. The oranges which had been The results for grapefruit and tangerines fol removed from the diphenyl pads and placed in lowed similar trends at lower and higher residue open crates after 2 weeks showed no increase in levels respectively. The average results for the decay over those left in cartons with diphenyl diphenyl residues in two orange varieties during pads. Enough diphenyl was apparently retained a 5-week storage period at 70° P are shown in to protect them for 3 weeks. Figure 3. No appreciable differences in residue levels Summary between waxed and unwaxed fruit were found. The oranges removed from the cartons after 2 1. Residues of diphenyl in citrus fruits in weeks and placed in open crates without diphenyl crease as the number of diphenyl pads placed in pads lost very little diphenyl during the addition the carton is increased. al 3 weeks of storage at 70° F. This may be due 2. Decay control in citrus fruits is improved to the presence of low concentrations of diphenyl as the number of diphenyl pads per carton is in the air of the storage room as indicated by increased. a gradual build-up of residues of diphenyl in the 3. Absorption and retention of diphenyl by untreated control samples. The oranges left in oranges are unaffected by solvent-type coatings cartons with diphenyl pads during the entire 5- on the fruit. week holding period showed only a very minor 4. Diphenyl residues persist at high levels in increase in diphenyl levels after the first 2 weeks. oranges for 3 weeks after the fruit is removed Figure 4 shows the average percentages of total decay of oranges during the 5-week storage CARTONS-5 WEEKS period at 70° F in the samples used in the study CRATES, AFTER 2 WEEKS IN CARTONS D CONTROL-A VE. WAXED. UNWAXED A WAXED ——• CARTONS -5 WEEKS O UNWAXED CRATES, AFTER 2 WEEKS IN CARTONS D CONTROL-AVE. WAXED. UNWAXED 60 A WAXED O UNWAXED > cl'4O 5*0 I20 20 0 12 3 w0 I 2 3 4 5 WEEKS OF STORAGE WEEKS OF STORAGE Figure 3.—Effects of a solvent-type wax on the absorp tion and retention of diphenyl by oranges during storage Figure 4.—Effects of residual diphenyl in limiting the in cartons for 5 weeks or in open crates for 3 weeks at decay of oranges removed from cartons with diphenyl pads 70° F after having been stored in cartons with diphenyl and then stored for 3 weeks at 70° F in open crates without pads for 2 weeks.