26 FLORIDA STATE HORTICULTURAL SOCIETY, 1946 is prohibited at the present time because its is known, the results reported here seem very toxic effect on humans is not yet known. hopeful that such a compound can be dis A few proprietary materials that have been covered. supplied by their distributors have been given very thorough tests for their ability to con Literature Cited trol rots. Paper mats containing some am 1. CHILDS, J. F. C. and E. A. SlEGLER. Con monium compound were found to give no con trolling orange decay. Ind. and Eng. Chem. trol over stem-end rot or molds when 8 to 24 38: 82, 1946. 2. CHILDS, J. F. C. and E. A. SlEGLER. Experi wafers were placed in a packed box of oranges. mental control of orange decays with thiourea. Various green paper wraps were extensively Phytopath. 34: 983-985, 1944. tested on oranges and grapefruit for their 3. HOPKINS, E. F. and K. W. LOUCKS. Keeping quality of oranges. Rept. to Fla. Citrus ability to control storage diseases in lighted Com/77. June 30, 1943 (Mimeographed). and darkened storage rooms. They were found 4. HOPKINS, E. F. and K. W. LOUCKS, and to have no effect on the diseases and shrink CHARLES" R. STEARNS, Jr. A study of cer age was just as great in the green wraps as tain methods for the control of stem-end rot it was in the light orange colored paper wraps and blue mold in oranges. Proc, Fla. State Hort. Soc. 57: 87-98, 1944. that are commonly used for wrapping citrus. 5. HOPKINS, E. F. and K. W. LOUCKS. Pulling Two epoxides, ethylene oxide and propylene versus clipping of oranges in respect to loss oxide, which were tried as fumigants proved from stem-end rot and blue mold. Proc. Fla. ineffective at any concentration that was low State Hort. Soc. 57: 80-86, 1944. 6. HOPKINS, E. F. and K. W. LOUCKS. Investi enough to be harmless to the fruit rind. gation of the fungicidal action of various Although at the present time no usable chemicals in respect to their effect on stem- chemical has been found that is highly effective end rot and mold fungi of citrus fruit. Fla. against citrus storage rots by any of the Exp. Sta. Ann. Rept. pp 174-175, 1945. 7. SNEDECOR, G. W. Statistical methods. Iowa methods so far. used, that is cheap enough to State College Press, Ames, Iowa. pp. 179- be profitable, and whose toxicity to humans 248, 1940. PROBLEMS IN THE DEHYDRATION OF ORANGE JUICE - Norman V. Hayes, Robert H. Cotton and now deprived of this valuable food. The de Wallace R. Roy : hydration can be stopped short of the powder National Research Corporation state to make a concentrate which can be sold as a frozen food. This frozen concentrate when Plymouth reconstituted with three times its volume of water closely approximates fresh juice. \ process has been developed employing The purpose of the present paper is to dis vacuum diffusion for the dehydration of or cuss the process and describe some of the ange juice to a virtually anhydrous powder. problems involved, as well as to present data The powder is extremely palatable and should in the hope that some duplication of effort go far in increasing the distribution of orange by other workers may be avoided. juice to segments of the world's population Orange juice is screened and circulated at a temperature of 55 °F. through concentrators 1 Presented before the American Society • of where the water is evaporated under vacuum Horticultural Science meeting, St. Louis, March 1946. until the concentration reaches 50 to 60% HAYS, COTTON AND ROY: ORANGE JUICE DEHYDRATION 27 solids. At this point some of the concentrate (9) has made blends of orange concentrate is further dried to powder, some is stored at containing, for example, 25% Valencia and 0° F. and the remainder is blended with fresh 75% Parson Brown or Hamlin juice. The juice to approximately 42% solids. This latter taste is superior to the Parson Brown or Ham operation restores volatiles lost by vacuum lin alone and,, therefore, these early season concentration. The addition of fresh juice to juices of very high ascorbic acid content, obtain optimum quality was developed by Dr. which are rather thin in taste, can be advan L. G. MacDowell of the Florida Citrus Com tageously used with late Valencia, which is mission. A public service patent for this pro full-bodied but rather low in ascorbic acid. cedure has been requested by the Commission. Harding's taste studies show that a ratio of The concentrate is introduced into large total soluble solids to anyhydrous citric acid vacuum driers where it is dried to a powder of at least 10 or 10.5 to 1 is necessary in order containing not more than 1.5% moisture at to have maximum palatability. Here again is temperatures in the order of magnitude of a useful tool in intelligent blending and room temperature. Pressures obtained in this scheduling. J step go as low as a few microns, with 100 Concentrate made in this laboratory of a microns typical of the end of the cycle. mixture of Hamlin arid Parson Brown juice In the drying of the concentrate to powder, was of higher palatability than the initial the driving force for movement of water vapor juice, probably because it was reconstituted in the vacuum is a trap in series with the to 12% soluble solids as compared to an initial pumping line. This is held below -50° F. and value of 9.5%. It had more "body." its surface is continually renewed by rotating Studies will have to be made over several scraping blades. In this way maximum ef seasons before precise recommendations on fectiveness is obtained from the refrigeration, blending can be made, however. since ice, which is a heat insulator, is never Orange juice is recognized as a rich carrier allowed to accumulate on the condensing sur of vitamin C. Table 1 summarizes changes in face. ascorbic acid in production of orange concen The powder and concentrate are readily re- trate having 50 to 60% solids. The mean hydrated to a drink containing 11.3% solids. retention was 96.6%. Data for six dehydra This serves to introduce the horticultural tions of juice to powder gave the following aspects of the problem. The processor buys recoveries in percentage, 97.3, 98.8, 92.3, 95.4, juice having from 9 to 15% solids but sells 96.6, 99.0. The mean retention was also 96.6%. on a fixed solids basis. Orange varieties hav It should be emphasized that these are pilot ing high solids content and capable of high plant data representing in some cases pur yields would be of great interest. Perhaps the posely drastic treatments for experimental time will come when oranges are sold on a reasons. The temperatures employed were solids basis. This would certainly encourage often greatly in excess of, and the times of further genetic research. treatment as much as several hundred percent Extremely thorough work by Paul L. Hard higher than, the current technique used in the ing (3, 4) and coworkers on seasonal changes pilot plant and the procedure used in the newly in Florida oranges forms a basis for planning constructed production unit, Vacuum Foods operational schedules of a dehydrating plant. Inc., formerly Florida Foods, Inc. Two values It gives data on solids, acid, ascorbic acid, pH, of 102% recovery were obtained. It is felt and ratio of total soluble solids to acidity as that they arise from sampling error. a function of time and rootstock. The work The stability of flavor and ascorbic acid in is a .guide to intelligent blending of orange any processed orange juice product is of tre juice which should go far in making for uni mendous significance. The vitamin C level formity in taste and in 'maintenance of a when the purchaser consumes canned, con relatively high level of ascorbic acid. Stahl centrated or powdered juice is important fromj 28 FLORIDA STATE HORTICULTURAL SOCIETY, 1946 the human nutrition viewpoint. Moore, Wie- Dowell and Heid (6) in a review of proposed derhold and Atkins (7) report for canned methods of making powder and concentrate orange juice retentions of 81.7 and 95.1% of quote Stevens (11) as saying that orange the initial ascorbic acid after six months stor- juice concentrate stored at' -5° F. for six age at 80 °F. and 40° F. respectively. The years retained over 90 percent of its ascorbic method of analysis used was the standard acid. Tests in this laboratory (Plymouth) for indophenol procedure. (2) Four batches of shorter periods confirm the above finding. TABLE 1—Changes in Ascorbic Acid Manufacture of Orange Concentrate Hav ing 50% Solids Ascorbic Acid mg/gm Percentage Run No. dry basis Recovery Fresh juice Concentrate Al 4.11 3.94 95.8 A2 4.53 4.38 96.6 A4 5.02 4.74 94.5 A6 4.84 4.76 98.4 A7 4.75 4.72 99.4 A8 4.29 4.22 98.4 A9 4.48 4.29 95.8 A10 4.37 4.05 94.8 All 4.39 4.13 94.1 A12 4.26 3.86 90.6 A14 3.91 4.01 102.0 A15 4.12 4.10 99.3 A16 4.65 4.65 100.0 A17 4.12 4.03 97.8 A18 4.25 4.11 96.7 A19 4.23 4.19 99.1 A21 3.99 3.77 94.5 A22 4.33 4.14 95.7 A23 3.99 3.92 98.2 A24 ,4.18 3.64 • 87.0 A25 4'.16 4.07 97.8 A26 4.24 3.96 93.4 A27 3.71 3.79 102.0 Mean percentage retention of ascorbic acid in concentrate 96.6% orange powder made by the vacuum diffusion Where a great many determinations of as- process were stored six months at about 80° F.