Preparation and Packing of Oranges for Shipment J. R. WINSTON,Bureau of Plant Industry, Department of Agriculture, Washington, D. C .
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HE preparation and
close to the fruit as possible and The green pigment which masks the orange packing of oranges for not to injure the skin in the color in some mature citrus fruits can be removed market involve a process. The boxes must not by ethylene gas applied under proper atmospheric number of special treatments. be filled too full or the fruit will conditions, preferably along with continuous As it is picked from the tree, be b r u i s e d w h e n one box is ventilation and air circulation. the orange is alive and its destacked on top of another. sirability as a food product deAntiseptics are applied to citrus fruit during COLORTREATMENT p e n d s u p o n its use not only handling io retard decay. An 8 or 10 per cent while it is still alive but while The color of mature oranges, borax solution applied within a few hours after i t retains as much as possible of grapefruit, and tangerines the fruit is harvested has given the most conthe quality of f r e s h n e s s and is extremely variable, owing sistent result; in decay prevention. Soap powfreedom from disease which it to varietal c h a r a c t e r i s t i c s , possesses a t the time of harvest. cultural practices, and weather ders, soda ash, and trisodium phosphate are To accomplish this, resort is had conditions. T h e orange the principal washing compounds used, with to refrigeration or various fungiand yellow pigments develop a trend toward the two latter containing rosin cidal treatments which repress beneath the green so that the compounds. The rosin aids in polishing the or prevent growth of rot organorange color may be completely fruit. isms, and to several other procm a s k e d b y t h e g r e e n . For esses which modify the rate of example, a June-bloom PineW a x emulsions are also used f o r polishing. metabolic activity in the fruit. apple orange of excellent flavor Precooling is commonly employed after packing Also, since most consumers still may appear to be grass-green if the borax treatment is not given during the “buy with their eyes,” various in color, but this green has a early stages of handling. With a n increasing treatments to improve the apdeep orange color b e n e a t h . use of antiseptics, precooling is being less genpearance of the fruit are cusLikewise, early-ripening oranges tomarily employed. However, may retain their g r e e n color erally used, as the latter serves to retard decay these comprise blanching and until late in the season or until only so long as the fruit is held at low temperapolishing methods for the most s e v e r a l c o l d p e r i o d s have tures, while the antiseptics aford protection at part and do not materially affect been experienced. The lateall temperatures. the c o m p o s i t i o n or e a t i n g r i p e n i n g v a r i e t i e s , such as aualitv of the fruit. the Valencia orange, lose their The first step in the preparation of oranges for market is green color in winter while they are still unpalatable, only to determine whether or not the fruit is properly matured. to turn green again when growth starts in the spring along Since the earliest shipments ordinarily command relatively with the return of hot weather. Their regreening, especially high prices, there is always an incentive to start shipments around the stem, occurs well in advance of the normal shipas soon as possible. The color of the fruit and other physical ping season for such varieties. A Valencia generally is characteristics a t the time of harvest cannot be relied upon much less green in color during the winter when the fruit as an indication of its stage of maturity as is the case with is still immature and sour than it is late in the spring when apples, peaches, and various other fruits. Thus, in order its flavor is most pleasing. I n the warmer sections of Florida, to safeguard against the marketing of immature sour oranges oranges rarely lose all of their greenish cast, regardless of which would disappoint consumers by their quality and the stage of maturity, while in other sections the same variethereby disappoint shippers by eventually killing the market ties may lose all of their green color long before they are for all oranges, maturity standards have been developed and edible. It appears, therefore, that the presence of green are enforced. These vary somewhat for different citrus pigments in the rind of citrus fruits is more of an index of fruits and in different producing sections, but in general are growth activity and weather conditions than of maturity or based upon the ratio of total soluble solids (chiefly sugars) to palatability. This has led to the development of the so-called “coloring” the acid in the expressed juice of a representative sample from each grove. For Florida oranges this ratio is 8 to 1. treatment which is the next step in the preparation of the Thus a chemical test is employed as the first step in the oranges for market. The use of the term “coloring” is unfortunate and misleading since it is frequently taken to marketing process. Oranges as well as all other fruits must be carefully mean an artificial coloring of the fruit which is not done. handled a t all times to avoid mechanical injuries which It is, in effect, a blanching process which causes the green afford entrance for rot organisms. Two species of Peni- chlorophyll to disappear and permit the previously masked cillium, P. italicurn and P. digitatum, are prevalent on citrus orange or yellow color to become fully evident. Used on fruit. The latter is capable of infecting fruits only a t points properly matured fruit, it involves no possibility of deception where the skin is broken or injured; the former also starts even to one who does not know citrus fruit. If attempts are a t such places but, in addition, is able to spread from fruit made to blanch immature fruit, the quality of the color to fruit by contact. I n the elimination of losses from these finally attained is not that of a typically mature fruit but fungi, therefore, careful handling of the fruit is extremely instead is a rather clear advertisement of its condition, at important. Precaution must be taken to cut the stems as least to those who are reasonably well acquainted with citrus I
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fruit. The process adds no color to that which has been attained naturally; it merely makes evident that which has been developed by the maturity and growing conditions of the fruit. While the treatment may produce, temporarily a t least, some slight effect in the respiraCROSS S E C T I O N tion of the fruit and in other p h y s i o l o g i c a l ~ ~ , = n C ~ ~ c ~ r , o or C H a M a r R effects, for all practical purposes the acidity and the soluble solids in the juice and the eating quality of the fruit remain unchanged. By means of this treatment it is possible to effect C#m CONNLC7lOH connLc as much removal of green color in the packing house within a few days as would normally occur on the tree in several weeks. The blanching or “coloring” treatment is not required on the entire crop, but the proportion treated varies from district to district and from season to season. I n Florida, the treatment is given ordinarily in specially constructed rooms a t the packing houses as soon as the fruit is received from the groves. The coloring rooms are equipped with air-conditioning apparatus so that the desired atmospheric temperature and humidity can be COLORfNG R O O M maintained and the requisite concentration of ethylene or other effective blanching agent can be maintained a t all times uniformly throughout the room. The coloring rooms generally have a capacity of one or two carloads of fruit. As a rule, separate air-conditioning units are provided for each room, some of the larger packing houses operating as many as twenty CROSS SECTION Or more units- As by Figure FIGURE 1. DIAGRAM O F CITRUS-COLORING ROOMAND AIR-CONDITIONING these air-conditioning units consist of a large APPARATUS blower, a heat radiator, steam and water jets, a thermostat, ventilating ducts, and necessary gas measuring duced into the circulating air in the room, the rate of apand regulating devices. The conditioned air is circulated plication being about 1 part to 30,000 or 50,000 parts of through the stacks of fruit into a flue opening a t the floor air. Under the older methods of coloring, ethylene was and is thence returned to the air-conditioner for recirculation. introduced in charges or “shots” a t intervals of 6 to 8 hours I n operating a coloring room, the first step is to raise the and at the rate of about 1 part to 4000 to 5000 of air. Under temperature of the fruit to 80-85’ F. within 10 or 12 hours, the latest method, popularly referred to as the “trickle maintaining a relative humidity of about 90 per cent with system,” the rate of coloring is more uniform, the time reone or two complete circulations of air per minute in order quired is only 24 to 48 hours as a rule, compared to 72 to to keep uniform fruit temperature throughout the room. 100 hours or more under the old shot system, the stimulation With the maintenance of uniform fruit temperature the rate of decay is less and the quality of the fruit is maintained of “coloring” is correspondingly uniform. The room is much better than with any of the older methods. ventilated continuously to admit a moderate amount of The temperatures maintained in the coloring process are fresh air and to prevent the accumulation of respiration above the optimum for Penicillium rots but are very favorable products of the fruit. I n properly operated rooms the carbon for Diplodia stem-end rot. It is therefore essential to reduce dioxide c o n t e n t of the -airthe time of t r e a t m e n t a s rarely reaches 0.25 per cent. m u c h a s p o s s i b l e , which The relative efficiency of points t o one of the chief the newer apparatus and proadvantages of t h e t r i c k l e cedure in quickly raising the system. temperature of the fruit in ANTISEPTIC WASHES all parts of the room and in maintaining the desired uniAntiseptic washes of variform atmospheric conditions ous kinds have l o n g b e e n as compared with the older used in citrus packing houses methods and equipment may to help reduce l o s s e s from be seen in Figures 2 and 3 d e c a y . Of these materials which present data obtained a s o l u t i o n of b o r a x h a s on commercial operation of generally been found to be these two methods. most effective and satisfacUnder the latest improved tory. Boric acid and mixm e t h o d s of c o l o r i n g a s tures of boric acid and borax IO 40 50 d e v e l o p e d by the B u r e a u 2o H O U F l O 30 are also effective but tend to of Plant Industry, ethylene burn the fruit. Sodium carFIGURE 2. FRUITTEMPERATURES AND ATMOSPHERIC CONgas is c o n t i n u o u s l y introDITION IN COLORING Roov UNDER 1 1 METHODS ~ ~ bonate is ~also u s e~d and is~
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quite effective against blue mold rot. Borax is generally preferred in Florida, however, because it is effective against the stem-end rots as well as the Penicillium decays. The common commercial practice has been to give the antiseptic wash after the fruit has been colored and in connection with the washing and scrubbing customarily given just before the fruit is packed. This practice has given good I
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growing sections. Consequently, large quantities of watersoftening compounds are used in citrus packing houses. The fruit is conveyed to large soaking tanks containing such detergents as cheap soap powder, trisodium phosphate, or soda ash, and is then carried through a washing machine equipped with scrubbing brushes. It is next conveyed through a tank containing a 5 per cent borax solution t o which it is subjected for 0.5 to 2 or 3 minutes. It is then rinsed under a spray of clean fresh water and is carried into a drying apparatus where warm air is blown over the fruit to evaporate the adhering water.
POLISHINQ The final process to which the fruit is subjected before packing is to give it a polish. This is usually done by passing it over horsehair brushes ranging in length from 9 to 18 feet. Sometimes a polishing material is added at this stage. For this purpose rosin is sometimes added to the washing solution, I I I I enough adhering to the fruit to be effective when brushed. 40' 10 20 Jo 40 50 60 70 HOURS A mixture of paraffin and mineral oil is also sometimes apFIGURE 3. FRUITTEMPERATURES AND ATMOSPHERIC CONplied in special machinery, while a carnauba wax emulsion DITION IN COLORING ROOMUNDER USUALMETHODS is likewise used to some extent. I n the latter case the emulcontrol of Penicillium rots but has not been as effective sion is applied by dipping the fruit into a tank of the material against the stem-end rots caused by Diplodia and Phomopsis, before i t enters the drier. This makes it unnecessary to use doubtless because of their accelerated growth into the fruit polishing brushes, which is especially desirable with tantissues under the conditions in the coloring room which are gerines since they are easily damaged by brushes. I n another polishing method bars of paraffin are held against the so favorable for their development. Accordingly, investigations by the Bureau of Plant Industry were initiated to determine whether application of the borax treatment before coloring would not be more effective. These studies have recently been concluded, and the results typically illustrated in Figure 4 strikingly demonstrate that the borax wash should be given as soon as possible after harvest and before the coloring treatment. This modification in procedure has already been widely adopted by the industry and is rapidly becoming the standard pracFIGURE4. EFFECTOF BORAXTREATMENT ON tice. DECAY (STEM-END ROT AND BLUE MOLD) IN ORANGESHELDAT 70" F . An 8 per cent solution of borax has been found most effective and economical, but the temperature of the solution must be maintained a t not more than 110' F. A momentary dip polishing brushes so that a small quantity of dry paraffin is into this solution has been found to be just about as effective brushed onto the fruit as it passes over the brushes. This is as a longer bath, indicating that it is the borax retained on perhaps the most widely used method, although many the fruit which is effective rather than fungicidal action in packers omit entirely the use of supplementary polishing the bath. This is further indicated by the fact that, when materials. the borax solution is washed from the fruit within 6 to 8 PACKINQ AND STORAQE hours after treatment, effective fungicidal action does not From the polishing machine the fruit passes t o the graders result. I n the case of fruit to be colored, the practice is to give the borax treatment before coloring and then to wash where it is separated according to quality and size. The off the borax deposit at the time of packing 2 or 3 days later. sized fruit of market grade is wrapped in paper impregnated The method of giving the borax treatment varies in differ- with mineral oil and then packed for shipment. However, ent packing houses, but perhaps the most practical method before being loaded into refrigerator cars, it is customarily thus far devised is to float the fruit through long tanks con- held in refrigerated rooms for precooling. I n Florida these taining the heated solution. While prolonged exposure to rooms are generally provided with an air blast of about 5000 the antiseptic is not required under all conditions, it has cubic feet per minute, changing the air about two and a half been found advantageous in weather when the fruit is cold. times per minute. The temperature of the air is held at Borax quickly crystallizes out of solution on cold fruit and 32' F. or lower in order to cool the fruit quickly. To further a relatively ineffective quantity adheres when such fruit is assist in quick cooling, the direction of the air blast is changed dipped only momentarily into the solution. The use of a every hour so that within 24 hours the temperature of the long tank permits the fruit to be warmed sufficiently in its fruit throughout the room is generally well below 40" F. passage to obviate the dificulty and is advantageous also Whether transit refrigeration is used or not depends upon in shortening the time required to warm the fruit to effective the condition of the fruit itself a t the time of loading and its coloring temperature when it is transferred from the borax market destination. The importance of prompt precooling and refrigeration will bath to the coloring room. Following the antiseptic and coloring treatments, the fruit be appreciated from the fact that the respiration rate of the is thoroughly washed, and the borax, soot, dirt, insects, and fruit follows rather closely van't Hoff's law; that is, it apother foreign matter are thus removed. I n Florida con- proximately doubles for every rise of 18' F. The respiration siderable difficulty is encountered in this process because of rate is a measure of metabolic activity and the consequent the very hard water which is found in most of the orange- approach of senility and ultimate breakdown of the tissues,
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with corresponding loss of eating quality. By promptly precooling the fruit after packing and thereafter holding it around 40” to 45” F., it can be preserved in the best physical condition and decay organisms can be held in check. Use of lower storage temperatures will provide greater safety against storage rots, prolong the storage life of the fruit, and possibly insure better eating quality, provided the fruit can be used immediately after removal from cold storage, How-
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ever, serious physiological disorders often develop under prolonged storage a t such lower temperatures (above the freezing point) and make it inadvisable to recommend their use commercially. RECEIVED April 2, 1934. Presented as part of the joint Symposium on Citrus Fruits before the Divisions of Agricultural and Food Chemistry and of Biological Chemistry a t the 87th Meeting of the American Chemic81 Society, St. Peteraburg, Fls., March 25 t o 30, 1934.
Citrus Fruit Juices from the Bottler’s Standpoint J. H. TOULOUSE, American Bottlers of Carbonated Beverages, Washington, D. C. Beverages containing citrus .fruit juices appear The bottler is interested in LTHOUGH we r e g a r d the use of fruit juices in less standardized than their eztract-flavored problems c o n c e r n e d with the preparation and distribution of carbonated beverages as analogs. Regional variations in standards are the bulk juices, but ,.hey are something quite new a n d more remote and not a part of modern, this is not altogether indicated. Data are given for average sugar, acid, carbon dioxide, and hydrogen-ion concenhis own sphere of activity. He true. The f i r s t c a r b o n a t e d desires from the manufacturer of b e v e r a g e s were made by the trations of becerages. Slight changes in bottling technic are necessary, but additional precautions the juice or c o n c e n t r a t e a addition of fruit juices andsugar material that will have and reto carbonated water 127 years must be obserced to eliminate spoilage which m a y tain its truly fruity taste, and ago when a druggist in Philato bacteria)Or to chemithat will present the least probdelphia used them to make the be due to yeast cals (chiefly oxidants). carbonated water he supplied lem of bottling or spoilage, Unfortunately, some of the on a physician’s prescription p r e p a r a t i o n s offered t o him more palatable. T e c h n i c a l difficulties connected with the preparation of the juices no in the past have been found undesirable either because of doubt had much to do with their virtual displacement by extensive chemical changes (such as oxidations) taking place flavoring extracts and essential oils, although for many years in the juice before he received it, or because of actual coninfusions of sarsaparilla bark or wild cherry were almost the tamination of the juice by yeast, bacteria, or molds which sole flavoring substances available. That fruit juices are caused great losses from spoilage and built up a prejudice again becoming possible for use in flavoring hottled carbon- against the product. ated beverages is due to vast improvement in the technic of COMPOSITION their preparation, for which the bottling industry has been compelled to wait The first consideration of composition is the relative quanWhile progress has been made in the chemical reproduction tity of citrus fruit juices used. The problem is so bound up of some essences, most of our modern flavors come chiefly with costs and the sales market that they must be considered from natural sources. The oils from lemons, oranges, and together, especially in relation to the 5 cent “roof” price limes are almost the sole source of the extract-type flavors under which about 90 per cent of all carbonated beverages of the citrus group. Vanilla beans are the source of the finer sell. of the “cream” soda water flavors. Ginger root and capsiVarious studies have shown that out of a total cost of 70 cum pods are extracted to flavor this standard American to 85 cents per case of bottles (about 1.25 gallons total) from beverage. Sarsaparilla, root beer, and birch beer are made 22 to 32 cents are for materials, with the rest of the total from mixtures of various herbs, roots, barks, leaves, and going for labor, selling cost, and delivery expense. The citseeds. Most of these do not possess a juice that can be ex- rus juices added to the beverage must not increase the matracted as such, but they are nevertheless true natural sources terial cost to any great extent or the selling price must also of our present-day carbonated beverages among which the be raised. At present there are preparations of citrus juices citrus fruit juices should take their own proper place. The which will give fruit juice content up to 7 and 10 per cent a t present paper is intended to point out wherein the use of costs which will allow the beverages to be sold a t the standcitrus fruit juices may be increased, by indicating fardts that ard sclling price. As costs can be lowered, the amount of may be remedied. juice can be increased, but any attempt to force public acFrom the bottler’s standpoint the use of citrus juices may ceptance of an increased price will result adversely to any be divided into two phases-composition and bottling technic. beverage. Because there exists this economic limit to the Consideration of composition involves several points : per- amount of natural juice, the question of standard juice concentage of juice that is feasible to use, the sugar, color, and tent cannot be considered. acid concentrations, as well as the costs of production, its It is often suggested that i t would be more desirable to use effect upon price, and the markets for the beverages. The whole juices and increase the selling price. Several years technic of bottling would cover such fields as the storage of ago (6) it was stated that a whole-juice lemon carbonated fruit juices, their deterioration and its causes, sanitary safe- beverage could be produced a t a cost of 1.5 cents per bottle guards, spoilage problems (both chemical and biological), for the raw materials and could retail a t 10 cents per bottle and new or different methods of bottling which are needed. with profit. This selling price would be an almost insur-
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