BULLETIN 71 FREEZE INJURY AND SUBSEQUENT SEASONAL CHANGES IN VALENCIA ORANGES AND GRAPEFRUIT (o o) E. T. BARTHOLOMEW W. B. SINCLAIR R. P. HORSPOOL CALIFO THE CO UNIVER The purpose of this study was o fi „d out how citrus fruits were affected by the freezing temperatures of the winter 1948-1949. THE CITRUS INDUSTRY WANTED TO KNOW the prob- able out-turn of frost-injured citrus fruits, the various stages of deterioration, and the recovery of fruits from various de- grees of frost injury. THIS PROBLEM IS IMPORTANT TO marketing agencies, shipping organizations, citrus products plants, and growers who are vitally interested in making an early estimate of crop damage. If such estimates can be fairly accurate — neither overly optimistic nor too conservative — serious losses may be prevented. HOW THE PROBLEM WAS HANDLED: The studies were confined almost entirely to Valencia oranges, with a few similar tests being made on Marsh grape- fruit. (Washington navels and lemons were studied follow- ing the 1913 freeze.) Fruit samples taken from groves known to be badly frozen, and from others thought to be lightly frozen were investigated periodically. These samples were inspected for crystallization (hesperidin crystals), drying of cell walls, a milky or cloudy condition on cross cuts, and granulation. Following observation, grading records and a final disposi- tion of the crop were made. Changes in internal appearance of the fruits were noted and photographed, and changes in juice content and com- position were determined by laboratory tests. THESE ARE THE RESULTS: • Young, immature citrus fruits that are injured by frost make a more nearly complete recovery than do mature or nearly mature fruits. Under southern California conditions, therefore, Valencia oranges, young lemons, and even grape- fruit have a better chance to recover than do navel oranges which usually are mature by the time of low temperatures. [2] Favorable weather conditions following the nights of low temperatures apparently aided recovery. • Under the prevailing conditions of the spring, summer, and early fall of 1949, mature Valencia fruits in the test plots remained on the trees from early May until the middle of August without showing a decrease in quality. There was a small decrease in quality, however, from the middle of August to October 10 when the fruits were picked. • Excessive peel thickness was not common among the test fruits. Albedo injury and surface injury to the peel were rare. • The tests showed that either a stem-end cut or both a stem-end and center cut are necessary if the extent and severity of freeze injury in Valencias are to be determined accurately. • A few more Valencia fruits were frozen in the stem end than in the center, many less were frozen in the stylar end than in either the stem end or center, and a much larger number of segments were frozen in the stem end than in either the center or stylar end. • The water-soaked appearance, gray or milky color, and hesperidin crystals disappeared from the entire fruit, or a portion of it, within three months after it was frozen. This is also true of many of the gelatinized vesicles, although some remained in severely frozen fruits. • Wavy segment walls and the light yellow, grainy con- dition of some vesicles did not disappear. Where hollow places occurred as a result of shrunken tissues in dead seg- ments, the remaining, noninjured segments enlarged to fill, or partially fill, the spaces. • Measurements of specific gravity of the fruit and mea- surements of juice on both a volume and a weight basis showed the X-ray and water separation on nonfrozen fruits to be more efficient than the separation by hand at the grading belt. • The average milliliters and percentage of juice per fruit (frozen and nonfrozen), on a weight basis, increased as the [3] season advanced, with the possible exception of the last test (October 10). • Total soluble solids and total sugars increased in both frozen and nonfrozen fruits from the time of the first test (February) until about the middle of August after which they began to decrease. The reducing sugars were more variable, but they also showed an upward trend. The concentration of soluble solids in the juice was not so high, nor were the acids so low, as in most years. • The total free acids decreased rapidly in both frozen and nonfrozen fruits from February 28 to April 25, but very little thereafter. In several instances, there was a temporary increase after April 25. • Granulation was much less severe in the 1949 Valencia crop than it is in most years. This is of special interest because many growers have thought that granulation is caused by low temperatures. • The response of both nonfrozen and frozen fruits to the effects of the different temperatures and humidities in the cold storage room and in the large, aerated room were not great enough to outweigh the natural differences that are always found in a series of samples from different sources. NOTE ON GRAPEFRUIT: • Freeze injury, based on number of frozen segments, was much more severe in grapefruit borne on the outside of the tree than in those borne on the inside. • The concentrations of total soluble solids and total sugars were higher in nonfrozen than in frozen grapefruit, regardless of their position on the tree. • There were no consistent differences in the concentra- tions of free acids in frozen and nonfrozen, "inside" and "outside" grapefruit. The following pages contain a detailed discussion of the ex- periments and the results obtained, with supporting illustra- tions and tables. A table of contents appears on the back cover. [4] FREEZE INJURY AND SUBSEQUENT SEASONAL CHANGES IN VALENCIA ORANGESandGRAPEFRUIT E. T. BARTHOLOMEW W. B. SINCLAIR R. P. HORSPOOL WEATHER RECORDS The following Weather Station temper- ature readings are given as a general in- dication of the conditions that prevailed. The temperatures in the plots from which the test samples were taken may have been higher or lower than the Weather Station readings. Most of the freeze injury occurred on the nights of January 3 to 7, 1949. The minimum temperatures on those nights were much below the freezing point at Placentia (22.8° F for 13 hrs.), Fuller- ton (23.2° F for 14 hrs.), and Anaheim (24.8° F for 7 hrs.) , the areas from which the Valencia samples for this study were taken. As noted, most of the freeze injury oc- curred on the nights of January 3 to 7, 1949, but it is possible that some of the fruits were injured on the nights of De- cember 23-24 and 24-25, 1948. At Pla- centia Weather Station No. 16, on the night of December 23-24, the tempera- ture was 28° F for 5 hrs. and 20 min., and 27° F for 2 hrs. and 10 min. At Fullerton Station No. 19, the readings on the night of December 24-25 were 28° F for 3 hrs., 15 min., 27° F for 2 hrs., 2 min., and 26° F for 1 hr. 1 There were no heaters or wind ma- chines in any of the groves from which the Valencia samples were taken. 1 All weather records mentioned in this paper were furnished by Mr. Roy J. Rogers, meteor- ologist at the U. S. Department of Commerce Weather Bureau, Pomona, California. NOTE: On February 7, 1949, several representatives of the citrus industry met at the University of California Citrus Experiment Station and asked that the Station undertake a study of the effects on citrus fruits of the freezing temperatures of the winter of 1948-1949. This publication is the result of such a study, and is Paper No. 649, University of California Citrus Experiment Station, Riverside, California. THE AUTHORS: Mr. Bartholomew is Professor of Plant Physiology and Plant Physiologist, Emeri- tus, in the Experiment Station, Riverside. Mr. Sinclair is Biochemist in the Experiment Station, Riverside. Mr. Horspool is Laboratory Technician in the Experiment Station, Riverside. [5] METHODS Several Valencia groves in northern Orange County were inspected repeatedly by packinghouse and field inspectors to determine approximate percentages of freeze injury. Following this, eight plots were selected, each from a different grove in the Placentia-Fullerton-Anaheim area. Each plot contained 25 trees. At the time the plots were chosen, four were supposed to show about 50 per cent and the other four about 25 per cent freeze injury in the fruit. None of the trees showed limb in- jury, but there was some damage to a few of the terminal leaves on new shoots in some of the plots. The approximate ages of the Valencia trees in the eight plots were : Plot: ABCDEFGH Age: 35 69 34 21 27 32 21 21 The first samples of fruit were picked on February 28, 1949. Successive samples were picked every two weeks between that date and October 10, 1949. Each sample consisted of six fruits from each of the 25 trees— 150 fruits from each plot at each picking. The fruits were not measured before picking, but were arbitrarily judged to be of medium size. The Valen- cias were outside fruits, and were taken from all sides of the trees and from the lowest branches to a height of about 6 feet. Grapefruit were taken similarly but from both outside and inside. The fruits from each plot were mixed as they were put into a container in the grove. In the laboratory they were thor- oughly mixed again so that they could be divided into two equal, representative lots of 75 each. The fruits to be used to deter- mine the quantity and quality of the juice were wiped with a moist cloth to remove surface dirt, weighed, and then cut trans- versely in the center. (All cuts made in these studies were transverse.) As these fruits were cut, they were segregated into two groups called "nonfrozen" (N) and "frozen" (F), and were weighed sepa- rately. The juice from the nonfrozen and frozen fruits was also measured and weighed separately. A large, electric hand reamer was used to extract the juice. The second lot of 75 fruits was used to determine the severity of freeze injury and to detect granulation when, and if, it occurred. In the first half of the season, this was done by making three transverse cuts, one near the stem end, one in the center, and one near the stylar end of each fruit. In the second half of the season, a fourth cut was made, which passed just below the surface of the pulp at the stem end of the fruit. This was made to deter- mine whether granulation was present. Separate records were made of (1) the total number of fruits showing freeze in- jury, (2) the number that showed injury in one portion only, (3) in two or more portions, and (4) the total number of segments injured in each portion. For both Valencias and grapefruit, all analytical determinations, such as for soluble solids, acids, and sugars, were made on centrifuged juice. The total sol- uble solids and specific gravity of the juice Avere determined with a ref Tactom- eter, the pH with a Beckman pH meter, the total acids by titration with a standard alkali solution and phenolphthalein indi- cator, and sugars by Blish's modified Hagedorn and Jensen method (1933, 1934). During the course of these studies, 328 determinations each were made on re- fractive indexes, soluble solids, acids, pH, reducing sugar, and total sugars. Actu- ally, the total for the two sugars should be 1,312 since each was determined in duplicate. The average of those duplicate determinations is the value reported. In all of the tests with both Valencias and grapefruit, 31,270 fruits were used. Half of these were used for juice analysis, the other half to determine the severity of freeze injury. [6] RESULTS— VALENCIA ORANGES General observations. — In the fol- lowing graphs and tables that refer to the quantity and quality of the juice, the fruits from which the juice was obtained are described as nonfrozen (N) or frozen (F). This refers to the condition of the fruit at the center cut only. (The juice could not have been reamed from these fruits had they been cut at the ends as well as at the center.) To interpret these data properly it should be remembered that a fruit that showed freeze injury at the center cut may or may not have been frozen, little or much, in one or both ends, and that a fruit that did not show freeze injury at the center cut may have had no, little, or much injury in one or both ends. To interpret the data from the lots of fruit that were used for reaming on a given date, see the data for the companion lot of fruits that were cut at the ends as well as the center, on the same date, to determine the severity and location of freeze injury in all parts of the fruit. From the general observations that were made on Valencia fruits in the groves before the laboratory studies were begun, it was concluded that a fruit might show one or more of the following types of injury. (These comments apply pri- marily to groves in which approximately 50 per cent or less of the fruits were judged to be injured by low temperatures, and they apply to Valencias only.) l.A water-soaked appearance indi- cated that the walls of many of the cells had become at least partially permeable and had permitted water to pass out of the cells into the intercellular and inter- vesicular spaces. After a few weeks, many of the fruits appeared to recover from this condition, indicating that the cells had been only temporarily changed and not killed. In fruits or parts of fruits where the cells had been killed, the water-soaked appearance gave way to drying and col- lapse of the tissues. 2. Often all, or a part, of the cut sur- face of the pulp had a pale gray or milky color, indicating that the carotenoid con- tent (yellow pigments) of the cells had become partially depleted (fig. 1). The milky appearance in the pulp is said to have been found in nonfreeze years. This may be true, but in the fruits observed in these studies the condition was pro- nounced in the frozen and not in the non- frozen fruits. It had largely disappeared by the last of March. 3. Hesperidin crystals were found mainly on the surfaces of two adjacent segment walls. These crystals appeared to be more abundant at some times than at others. They had practically disappeared by the latter part of March. 4. Some of the injured fruits had wavy or "snaky" segment walls (fig. 2). This condition is difficult to explain. In some cases, it appeared to have been caused by shrinkage of the pulp. In other cases, por- tions of the segment walls appeared to have gelatinized or grown and protruded into the adjacent tissues. Not all injured fruits had wavy segment walls, but when they occurred, they were usually much thicker than those in the uninjured fruit. In severe cases it was not uncommon to find gum pockets within these segments, most often in the narrow angles of the segments next to the central axis (fig. 3) . Those who have made repeated observa- tions on the development of the wavy seg- ment wall state that at first it becomes water-soaked, gelatinous, and much thick- ened. Later, it becomes somewhat de- hydrated and pale yellow in color but it never returns to its natural straightness, thickness, and color. 5. Another rather conspicuous type of injury was the development, in most any portion of the pulp, of vesicles (juice sacs) in various stages of gelatinization. In most cases these vesicles were isolated with not more than one to two or three [7] Fig. l. — Pale or "milky" appearance of the cut surface. F i g . 2. — Wavy or "snaky" segment walls. / ' -■ >. i Fig. 3. — Gum pockets. f :.:* [8 Fig. 4. — Scattered groups of gelatinized vesicles. " T Fig. 5. — Light yellow grains or granules in some vesicles. :4 V [9] Fig. 6. Two segments for- merly hollow but now filled or nearly filled in due to excessive growth of noninjured segments. Kodacbromes by L. J. Klotz adjoining each other. These vesicles ap- peared to be in the early stages of granu- lation (fig. 4). This condition, however, was seldom found in any of the fruits that were examined after the middle of April. 6. In the segments of some fruits, a few to several vesicles were partially or entirely killed. In many such fruits, not enough vesicles were injured in any one portion of a segment to cause any notice- able collapse. The injured portion of such vesicles had become light gray to yellow in color, and had a somewhat grainy ap- pearance (fig. 5) . There was no evidence that such vesicles recover. 7. Perhaps the most noticeable type of freeze injury was that in which all of the vesicles were killed in a part, or all, of one or more segments. In such cases, the vesicles lost water, collapsed, and left hol- low spaces in the segments. Where only a portion of a segment, or even one or two entire segments, was injured, excessive growth in the uninjured segments often caused them to extend into the hollow spaces and fill, or almost fill, them (fig. 6) . Such growth conditions could occur in these fruits because they were immature when partially frozen. 8. Fruits rarely showed serious freeze injury on the surface of the peel. Such areas were characterized by the usual drying, shrinking, and toughening and by a light to chestnut brown color in small or large patches, caused by the oil which escaped from the injured oil glands. Other types of surface injury to the peel were : lack of luster, retention of green color, sometimes an excessive re- greening, localized ridges and bumps, or general coarseness and a flattening of the peel directly outside the injured pulp tissues. While exact peel thickness data were not obtained, general observation led to the conclusion that only a relatively few of the fruits used in these studies had ex- cessively thick peels as a result of freeze injury. These were on the fruits that were frozen in all or nearly all portions of the pulp. On the fruits in which half or less of the pulp had been frozen, there was very little, if any, excessive thickening of the peel. 9. No visible injury could be detected in the albedo (white portion of the peel) of any of the fruits. LABORATORY TESTS Total freeze injury in all parts of fruits tested. — The total percentages of Valencia fruits frozen in at least one seg- ment or portion of a segment, at each of the seventeen tests between February 28 and October 10, 1949, are shown in Table 1. The values for four of the plots— those in which the fruits were most severely injured— are given in Figure 7. Both the table and the figure represent the averages for 75 fruits from each plot on each date. The total amounts of freeze injury in the fruits decreased as the season advanced. For example, the maximum in Plot D was 73.3 per cent on March 14, the minimum, 26.7 per cent on October 10; in Plot H, the maximum was 36.0 per cent on March 14, the minimum, 2.7 per cent on both September 26 and October 10. As would be expected in random sampling, the per- centage of freeze injury in the fruits on different dates varied considerably. For example, the amount of injury in Plot A was 50.7 per cent on August 1, only 33.3 per cent on the preceding date (July 18) , and 38.7 per cent on the following date (August 15). No single factor accounts for the general decrease in the percentage of fruits that showed freeze injury as the season advanced. Some of the fruits dropped, but tests in the early part of the season showed that these were about equally divided between frozen and non- frozen. Further tests of this nature were [10] not made during the remainder of the season. In taking all samples, an effort was made to select exposed, outside fruit only, but toward the end of the season, especially on trees that had the least amount of fruit, some fruits had to be chosen that had been at least partially protected by foliage. It is of interest to note, however, that the same general de- crease in injury was found in fruits from plots where an abundance of outside fruits remained on all of the trees at the end of the season (October 10). A third ex- planation is that by far the greater per- centage of the fruits from all plots showed recovery. In some fruits, the recovery was only partial, in others almost complete, in so far as juice quantity and quality were concerned. In some fruits, the ad- joining segments had enlarged abnor- mally so that they had filled or almost filled the hollow of the injured segment (% 6). It is also of interest here to note that after about the middle of March, rela- tively few fruits, nonfrozen or frozen, dropped from the trees in any of the plots, even fewer than in some years when there had been no freeze injury. In general, this condition prevailed in all of the groves in the area where the test plots were located." 2 Observations to date (middle of March, 1950) have shown that the drop of both non- frozen and frozen fruits has been much more severe following the freezes in early January of this year (1950) than it was following the freezes of late December, 1948, and early Jan- uary, 1949. There are some exceptions, but this condition appears to apply quite generally to all of southern California. TABLE 1 — Percentages of Valencia Fruits that Showed at Least One Frozen Segment in One or More Portions of the Fruit 1 FEBRUARY 28 TO OCTOBER 10, 1949 Plot Feb. 23 March 14 March 28 April 11 April 25 May 9 May 23 June 6 A 44.0 48.0 30.7 58.7 58.7 44.0 13.3 24.0 50.7 54.7 40.0 73.3 70.7 40.0 36.0 36.0 42.7 50.7 28.0 57.3 48.0 29.3 10.7 26.7 48.0 52.0 16.0 65.0 49.3 40.0 21.3 14.7 44.0 66.7 10.7 50.7 52.0 37.3 20.0 8.0 53.3 50.7 12.0 46.7 45.3 33.3 13.3 9.3 46.7 52.0 9.3 42.7 46.7 14.7 10.7 5.3 40.0 33.3 4.0 48.0 45.3 21.3 5.3 13.3 B C D E F G H Plot June 20 July 5 July 18 August 1 August 15 August 29 Sept. 12 Sept. 26 Oct. 10 A 37.3 40.0 14.7 38.7 49.3 40.0 12.0 8.0 37.3 29.3 9.3 29.3 41.3 25.3 12.0 9.3 33.3 26.7 8.0 34.7 37.3 37.3 9.3 6.7 50.7 10.7 36.0 33.3 29.3 12.0 5.3 38.7 4.0 37.3 37.3 24.0 9.3 6.7 36.0 10.7 40.0 37.3 25.3 6.7 4.0 42.7 8.0 37.3 28.0 28.0 8.0 6.7 41.3 6.7 28.0 32.0 24.0 4.0 2.7 29.3 6.7 26.7 31.5 17.3 4.0 2.7 B C D E F G H 1 Based on 75 fruits from each plot on each date, a total of 9,750 fruits. 2 Plot picked by mistake. [11] PLOT A 60 o UJ z 2 40 20 / ^\ * — r . /\PLOT D 60 / V '\ 40 "^^ '\/ ^\._ 20 PLOT F 60 - 40 "X/ \ /* v /x \ __. 20 \s 28 14 28 II 25 9 23 6 20 5 18 1 15 29 12 26 10 FEB. MARCH APRIL MAY JUNE JULY AUGUST SEPT. OCT. SAMPLING DATES— 1949 Fig. 7.— Percentages of freeze injury in Valencia oranges as the season advanced. (See table 1 for these and other values.) [12 Fruits frozen in one portion only. — Freeze injury was found in only one portion of some of the fruits, that is, in either the stem end, the center, or in the stylar end (table 2) . With the excep- tion of those from plots C, G, and H, about as many fruits showed freeze injury in one portion only at the close of the season as at the beginning. All plots ex- cept B and D had more fruits frozen in the stem end than in either the center or the stylar end. In all, 1,431 (14.7 per cent) out of 9,750 fruits were frozen in one portion only. The injury in a given portion of a fruit was often confined to a single segment, but in the same portion of other fruits, several or even all seg- ments were frozen. As shown in Table 2, fewer segments were frozen in the stylar end than in either the stem end or the center. Fruits frozen in one or more por- tions. — Table 3 shows, for each plot, the total numbers and percentages of fruits frozen in the stem end only, center only, stylar end only, and in the following combinations: stem end + center; stem end + stylar end; center + stylar end; and stem end + center + stylar end. The data in this table thus give a complete picture of the total number of fruits frozen and the location of the injury. There is no duplication. A fruit that is counted in one group is not counted in any other. The table shows that Plots C, F, G, and H had the greatest number of fruits frozen in the stem end, Plot B in the center, Plot E in the stem end + center, and Plots A and D in the stem end + center + stylar end. Figure 8 shows this for Plots A, D, E, and F, which had the greatest amount of freeze injury. Note the marked differ- ences in values for a given plot and in values for the different plots. Referring to the total number of frozen fruits for each plot (next to last column in table 3), we find that the two groups which had the greatest number of frozen fruits (1 and 4) were the stem end only (650 fruits) and the stem end + center only (679 fruits) . Approximately 47 per cent of the frozen fruits were in these two groups. Of further interest is the fact that the total number of fruits frozen in the stem end (groups 1, 4, 5, and 7) was a little greater than the total number frozen in the center (groups 2, 4, 6, and 7) — 1,952 and 1,897, respectively. Severity of freeze injury. — The data in Table 4 and Figure 9 have been so arranged as to divide the degrees of freeze injury to Valencia fruits into two groups. The first half of the table and the cross-hatched portion of the columns in the figure deal with fruits in which two or fewer segments were frozen. The second half of the table and the open portions of the columns in the figure deal with fruits in which three or more segments were frozen. Referring to the table and the figure for the first group, we find that more fruits and more segments were frozen in the center than in either the stem end or stylar end. Three individual plots, however, D, G, and H (table 4), showed higher totals for the stem end than for the center. In the second group, there were 131 more fruits and 1,098 more segments frozen in the stem end than in the center. Only one plot (B) had more fruits frozen in the center than in the stem end. In all plots, the stem end had the greatest num- ber of frozen segments. In both groups, the total numbers of fruits and segments frozen in the stylar end were much lower than those in the other two portions of the fruit. Considering all individual tests for all plots (130 tests, 75 fruits each), there were only 15 instances in which the greatest number of fruits were found to be frozen in the stylar end, and only 10 instances in which the greatest number of frozen segments were found in that portion. 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I '£■ fc CO CO rH ON rH t- 3 •o 4h (2g ON |IO I © CD CO t- 00 Pi id id C-' ** co* id t-' 3 «A rH ON ON rH M 5 M op s d CD *i © rH ON rH CO o- V fc lO © ON © rH ON CO cc ► CO c s Ul —1 pSs © CO ■*)« ON t- ON ON 5 00 o* co* oo co ■*" co' ©' V < ON rH rH ON a r- < ^ d IO OO ^i CO IO t> ^l O 00 ^ G> ON rH IO rH rl t- o. !zi CN it: 1 •o PI hi CO o >» 3 d a » H O u > c ° + O xi CO '3 hi > > £ SS S 1 .SB 53 1 5 1 rs o co t< o o c §*§++£+ O n o h O isi-aa+i a 1 O h , t) I h t) s§« s s|a 3 o H P! w o oa w w o w CO H Pi 5J O rH ON CO ■* IO CO t- o 15] STEM END CENTER STYLAR END STEM END a CENTER STEM END a STYLAR END CENTER a STYLAR END STEM END, CENTER a STYLAR END PLOT A 3 PLOT D : ■ STEM END CENTER STYLAR END STEM END a CENTER STEM END a STYLAR END CENTER a STYLAR END STEM END, CENTER a STYLAR END PLOT E PLOT F - , . . 10 20 30 40 10 20 30 40 FREEZE INJURY-PER CENT (TOTAL FRUITS FROZEN) Fig. 8.— Distribution of freeze injury in Valencia oranges. (See table 3 for these and other values.) was thoroughly stirred just before meas- uring. Because the presence of the tissues in the juice made the volume somewhat difficult to read, its exactness was checked by weighing each lot of juice. A compari- son of the two sets of values showed that those given for volume on a milliliter basis are approximately correct. These are given in the table, therefore, because they are more common and more easily interpreted. Attention is called to the fact, however, that the presence of a consider- able quantity of pulp tissue in the juice gives higher values in Tables 5 and 6, than if most of the tissues had been screened out, as is done commercially, before the juice was measured and weighed. It should also be noted that, although they may be somewhat high, the values for both nonfrozen and frozen fruits were obtained in the same manner and are therefore comparable. The values presented in Table 5 and Figure 11 show that the nonfrozen fruits contained 5 to 25 per cent more juice than did the frozen ones. In all of the lots that contained frozen fruits there were, how- ever, 24 instances in which the average weight of the frozen fruits was equal to or greater than that of the nonfrozen fruits. Nevertheless, in all of these instances the nonfrozen fruits contained more juice per fruit than did those that were frozen. The fact that the weight of a frozen fruit was less than that of a nonfrozen does not necessarily mean that the frozen fruit was the smaller. A large, badly frozen fruit may weigh less than a considerably smaller, nonfrozen one. The data in Table 5 show that a fruit sample with a total [16] freeze injury of 45 per cent may have a juice content equal to 43 per cent of its weight, while a sample with only 28 per cent freeze injury may have a juice con- tent equal to only 37 per cent of its weight. Again, a fruit that shows no freeze in- jury at the center cut may have less juice than one frozen at the center. The results emphasize the need to determine the severity of freeze injury in all portions of the fruit. As will be brought out later, the variations in specific gravity, even in noninjured fruits, were probably a factor in causing this condition. There were variations in the amounts of juice per fruit from the different plots on successive sampling dates but, in gen- eral, there was a gradual increase. In four instances, the amounts of juice per fruit on October 10 were twice those of February 28. Two of these instances (plots A and D) were in frozen fruit and TABLE 4 — Different Degrees of Freeze Injury in Valencia Orange Fruits 1 Plot No. fruits frozen in : No. segments frozen in : Av. no. frozen segments per portion of fruit Stem end Center Stylar end Stem end Center Stylar end Stem end Center Stylar end Not more than two segments frozen A 154 130 65 182 182 126 65 55 186 149 46 195 192 150 60 57 134 94 24 136 116 104 21 21 234 215 103 279 288 188 98 90 280 235 77 293 290 242 83 81 204 134 28 203 178 161 22 28 1.5 1.7 1.6 1.5 1.6 1.5 1.5 1.6 1.5 1.6 1.7 1.5 1.5 1.6 1.4 1.5 1.5 1.4 1.2 1.5 1.5 1.5 1.1 1.3 B C D E F G H All plots: Number. . . Per cent. . . 959 36.3 1,035 39.1 650 24.6 1,495 36.2 1,681 40.6 958 23.2 1.6 1.6 1.5 Three or more segments frozen A B C D E F G H 216 97 52 206 215 108 49 50 171 131 37 193 193 81 28 28 103 47 14 73 40 20 4 1,068 461 223 954 1,065 465 196 218 765 453 160 825 800 328 112 109 441 168 56 306 153 92 20 4.9 4.8 4.3 4.6 5.0 4.3 4.0 4.4 4.5 3.5 4.3 4.3 4.1 4.0 4.0 3.9 4.3 3.5 4.0 4.2 3.8 4.6 5.0 0.0 All plots : Number. . . Per cent. . . 993 46.0 862 40.0 301 14.0 4,650 49.3 3,552 37.6 1,236 13.1 4.7 4.1 4.1 1 A total of 9,750 fruits examined. 17] 50 FROZEN SEGMENTS PER FRUIT V77A 2 OR LESS I 1 3 OR MORE I W LOCATION S < OF INJURY uj z v uj I— iij i— i- 10 o CO en PLOT A Fig. 9.— Different degrees of freeze injury based on number and location of frozen segments in different portions of the fruit. (See table 4 for these and other values.) < < 1- _i 2 1- _l z > UJ > Ml i- I- H O co o tn D E two (plots G and H) in nonfrozen. The amount of juice per fruit increased as the season advanced because of the normal increase in size of fruit, the normal in- crease in percentage of juice vs. tissues, and the recovery, or filling in, of some of the frozen segments (fig. 6) . It should be noted that some of this increase may have shown up as a result of error in selecting samples. Although care was taken to choose medium-sized fruits for each sample, it is possible that, as the season advanced, the fruits chosen may have been slightly above average. NOTE: The terms "nonfrozen" and "frozen," as used in this section, refer to condition of fruits exposed by the center cut only. Juice — per cent of weight of fruit. — From February 28 to August 29, there was a general increase in the per- centage of juice in the fruits on a weight basis (table 6 and fig. 12 for plots A, D, E, and F) . After August 29, there was no definite increase. Between those two dates, the increase for the nonfrozen fruits ranged from 20 to 42 per cent, that for the frozen (counting only plots A, D, E, and F), from 30 to 56 per cent. In these four plots, the amount of juice in the frozen fruits increased an average of 38 per cent; in the nonfrozen, the increase was only 28 per cent. The data thus show that the frozen fruits made an appreciable recovery. Since the values in Table 6 are in terms of per cent of weight of fruits, they can be easily converted to pounds of juice per ton of fruit. The amounts of juice in the fruits from the eight plots were not determined on a volume-per-fruit basis, but on a weight basis only (table 6 and fig. 12). The [18] NUMBER OF FROZEN FRUITS AND SEGMENTS FRUITS^X^SEGMENTS FRUITS-J^SEGMENTS Fig. 10.— Diagrammatic representation of the number of fruits and segments frozen in each of the three different portions of the fruit— stem end, center, and stylar end. TABLE 5 — Yields of Juice from Nonfrozen and Frozen Valencia Oranges (Ml. per Fruit) Plot Condition of fruit Feb. 28 March 14 March 28 April 11 April 25 May 9 May 23 June 6 A B C D E F G H N 1 ml. 44 33 44 36 46 36 40 31 35 34 52 38 45 32 45 33 ml. 48 36 45 35 48 34 40 35 38 31 52 35 46 31 47 30 ml. 51 41 46 36 55 37 44 37 40 33 57 49 53 39 50 38 ml. 52 45 49 40 57 38 51 40 44 40 55 42 59 40 57 3 ml. 53 48 57 41 61 54 41 48 43 63 39 60 43 59 ml. 55 48 57 46 64 60 45 47 37 62 53 65 _ 3 60 ml. 59 50 58 49 68 60 47 54 43 68 54 67 63 ml. 55 44 55 45 64 53 46 49 40 58 46 67 67 F 1 N F N F N F N F N F N F N F Plot Condition of fruit June 20 July 5 July 18 August 1 August 15 August 29 Sept. 12 Sept. 26 Oct. 10 A B C D E F G H N 1 ml. 60 52 60 52 69 65 61 54 47 71 59 73 71 ml. 64 58 60 55 76 66 55 56 50 71 58 81 76 ml. 67 56 60 55 71 64 61 56 46 68 57 82 78 ml. 65 54 2 2 74 74 65 55 46 72 59 87 79 ml. 68 56 76 74 61 59 48 77 64 90 81 ml. 69 55 79 74 69 65 56 80 68 90 83 ml. 70 61 78 71 60 60 53 75 66 90 82 ml. 72 60 80 74 68 61 52 79 67 87 86 ml. 74 69 80 78 62 62 55 83 67 94 90 F 1 N F N F N F N F N F N F N F i N = No segments frozen at center of fruit; F = one or more segments frozen at center of fruit. In either case, however, the fruits may or may not have been frozen in one or both ends. 2 Plot picked by mistake. » Not enough frozen fruit to insure significant results. [20] .PLOT A 70 50 30 PLOT D 70 50 30 . 70 -J 2 UJ 50 O 30 .PLOT E . ^ /"^^^--^ <:n:;/ : ""^-;""' ;"' .PLOT F ^^s^ ^ -^ 70 ■ /\ / """^ ^^ 50 -KC\ \/ .... VALENCIA ORANGE NONFROZEN FROZEN 28 FEB. 14 28 MARCH II 25 9 23 6 20 5 18 1 15 29 APRIL MAY JUNE JULY AUGUST SAMPLING DATES — 1949 12 26 SEPT 10 OCT. Fig. 1 1.— Average yields of juice (ml. per fruit) from nonfrozen and frozen Valencia oranges. (See table 5 for these and other values.) amounts of juice were later determined on a volume basis, in the separator tests. Total soluble solids. — There was a gradual increase in total soluble solids in the juice from both nonfrozen and frozen fruit until the latter part of the season (table 7 and fig. 13) . The table gives the value for each determination for each plot, but the curves in Figure 13 show the trends for only four plots— those which furnished enough frozen fruits to give re- liable results during the entire season. [21] TABLE 6 — Yields of Juice from Nonfrozen and Frozen Valencia Oranges (Per Cent of Weight of Fruit) ALL FIGURES ARE PER CENT Plot Condition of fruit Feb. 28 March 14 March 28 April 11 April 25 May May 23 G H N 1 . F 1 . N. P.. 43 34 43 42 47 37 43 32 41 36 49 37 40 33 41 32 47 39 46 37 46 38 38 39 42 36 53 38 44 38 44 33 49 42 47 39 49 40 46 38 40 37 50 42 46 53 35 50 45 48 40 50 39 47 40 45 39 51 44 47 35 47 49 45 49 42 50 47 39 46 40 52 37 45 37 47 51 45 51 44 52 48 40 48 38 52 43 48 48 53 47 51 44 50 50 41 48 41 53 47 49 49 Plot Condition of fruit June 20 July 5 July 18 August 1 August 15 August 29 Sept. 12 Sept. 26 Oct. 10 A N 1 F 1 54 48 53 43 53 54 42 45 43 54 51 53 51 53 46 53 46 55 53 46 50 47 55 44 52 53 56 49 54 47 56 53 49 52 44 56 47 54 59 56 48 2 2 57 54 49 52 45 57 46 55 55 56 49 57 55 46 53 43 54 51 55 56 57 47 58 55 50 54 47 59 48 57 55 58 51 58 55 49 53 48 64 53 57 55 59 50 58 59 51 54 48 59 52 57 58 58 54 B N F c N 59 F D N 58 F 46 E N 53 F 48 F N F 60 48 G N 59 F H N 57 F i N = No segments frozen at center of fruit; F = one or more segments frozen at center of fruit. In either case, however, the fruits may or may not have been frozen in one or both ends. 2 Plot picked by mistake. 3 Not enough frozen fruit to insure significant results. [22] PLOT A 60 ■ . -~"—— 50 yS* 7:r;^\/---'''-- -'"'"-'" 40 y s 60 £ 50 CO < CD 40 - 30 PLOT D /\ nZ - PLOT F /\ 60 ./^ ^ - ' , ^ a / 50 ^y'' ^ . ■ * ' "** '" -x /'\ / \-^ ""—•*•' VALENCIA ORANGE 40 * / \/ NONFROZEN ■*n FROZEN 28 14 28 II 25 9 23 6 20 5 18 I 15 29 12 26 10 FEB. MARCH APRIL MAY JUNE JULY AUGUST SEPT. OCT. SAMPLING DATES — 1949 Fig. 12.— Average yields of juice (wt. basis) from nonfrozen and frozen Valencia oranges. (See table 6 for these and other values.) Figure 13 shows that the spread be- tween the values for nonfrozen and frozen fruits was greatest for Plot A, and smallest for Plot E. No definite reason for this difference in spread can be given, but the following is a possible explanation. Table 1 shows that the total percentage of frozen fruits from the two plots was ap- proximately the same, but Table 4 shows that, while the total numbers of frozen segments in the stem end and center were about the same, the number frozen in the [23] TABLE 7 — Total Soluble Solids in Juice of Nonfrozen and Frozen Valencia Oranges ALL FIGURES ARE PER CENT Plot Condition of fruit Feb. 28 March 14 March 28 April 11 April 25 May 9 May 23 H 9.11 9.01 9.91 9.91 9.83 9.74 9.71 9.23 9.23 9.23 8.91 8.73 10.91 10.68 10.17 10.01 9.11 8.57 9.91 9.83 9.71 9.63 9.57 9.23 8.91 8.63 9.71 9.17 10.57 10.41 10.03 9.57 9.91 9.06 10.23 9.91 9.91 9.31 9.71 9.23 9.71 9.51 9.23 8.63 9.71 10.63 10.17 9.91 10.11 9.37 10.43 10.23 10.03 9.43 9.77 9.11 9.91 9.57 9.83 9.11 10.43 10.11 10.17 9.71 9.37 10.57 10.57 10.57 9.71 8.83 10.43 9.91 9.97 9.11 10.37 10.21 10.17 10.83 9.23 11.31 10.57 9.97 10.17 9.11 10.57 9.77 10.31 9.23 10.57 10.23 10.63 9.23 11.03 10.31 9.97 9.43 8.63 10.17 9.71 10.03 9.37 9.91 10.03 Plot Condition of fruit June 20 July 5 July 18 August 1 August 15 August 29 Sept. 12 Sept. 26 Oct. 10 A N 1 11.23 9.77 11.23 11.03 10.77 11.91 10.23 11.71 11.31 11.23 9.97 9.11 11.23 10.57 11.03 10.23 10.51 10.57 11.43 9.91 12.01 11.91 11.37 10.57 9.31 11.51 10.83 11.37 9.97 10.57 10.57 11.96 10.57 2 2 11.57 10.37 9.71 11.51 10.97 11.51 10.57 11.03 10.97 11.91 10.57 12.01 10.71 9.63 11.63 10.97 11.43 10.31 11.11 10.97 11.71 9.31 11.91 10.51 9.51 11.23 10.37 11.23 10.63 11.23 11.11 11.57 10.11 11.91 10.57 9.51 11.20 10.43 10.63 10.77 11.37 11.03 11.57 9.71 12.01 10.57 9.43 11.17 10.37 11.23 10.57 11.23 11.03 11.77 F 1 9.91 B N F C N F. . . 11.96 D N 9.83 9.11 11.03 10.43 10.63 10.17 10.23 10.37 F 9.23 E N 10.83 F 9.43 F N 10.97 G F N 9.06 11.23 F H N 10.37 11.17 F 1 N = No segments frozen at center of fruit; F = one or more segments frozen at center of fruit. In either case, however, the fruits may or may not have been frozen in one or both ends. 2 Plot picked by mistake. 3 Not enough frozen fruit to insure significant results. [24] II PLOT A " / i i i i i i _ ""^y * ' » ~~ J 1 J 1 10 9 \c PLOT D II o ^y^^ 10 ^^" S >v . ■' 9 V i 1 1 1 1 1 1 \c PLOT E . . -^ II ^Z^"' • • "> 10 \ s \ 9 Y . i i i i I l ._i J. i 1 1 1 1 12 10 PLOT F VALENCIA ORANGE ^^ *^"""'\ v^^ NONFROZEN FROZEN s s — ^ / \ \ \ \ \ \ \ ,.l i 1 1 1 1 1 1 1 1 1 1 1 1 1 28 14 28 II 25 9 23 6 20 5 18 I 15 29 12 26 10 FEB. MARCH APRIL MAY JUNE JULY AUGUST SEPT. OCT. SAMPLING DATES-1949 Fig. 13.— Total soluble solids in the juice of nonfrozen and frozen Valencia oranges. (See table 7 for these and other values.) [25] TABLE 8 — Concentrations of Free Acids (as Citric) in Nonfrozen and Frozen Valencia Oranges ALL FIGURES ARE PER CENT Plot Condition of fruit Feb. 28 March 14 March 28 April 11 April 25 May 9 May 23 June 6 A B C D E F G H N 1 2.04 2.01 2.15 2.15 2.06 2.02 2.17 2.06 2.13 2.01 1.98 1.93 2.57 2.45 2.49 2.40 1.86 1.80 1.94 1.91 2.16 2.16 1.99 1.98 1.95 1.82 1.70 1.67 2.26 2.19 2.17 2.00 1.79 1.58 1.84 1.77 1.93 1.72 1.75 1.65 1.82 1.65 1.55 1.40 1.93 1.87 2.07 2.07 1.57 1.39 1.58 1.47 1.72 1.46 1.49 1.36 1.52 1.34 1.38 1.30 1.76 1.70 1.73 3 1.16 1.04 1.24 1.23 1.30 3 1.15 1.10 1.21 1.14 1.12 1.05 1.43 1.35 1.40 1.37 1.19 1.41 1.36 1.46 1.31 1.25 1.39 1.27 1.23 1.14 1.63 1.55 1.34 1.17 1.45 1.35 1.43 1.25 1.18 1.30 1.24 1.23 1.16 1.52 1.55 1.23 1.15 1.30 1.28 1.39 1.21 1.17 1.29 1.19 1.20 1.11 1.46 1.32 pi N F N F N F N F N F N F N F Plot Condition of fruit June 20 July 5 July 18 August 1 August 15 August 29 Sept. 12 Sept. 26 Oct. 10 A B C D E F G H N 1 F 1 N 1.23 1.10 1.19 1.21 1.33 1.20 1.15 1.25 1.24 1.26 1.10 1.09 1.26 1.18 1.19 1.16 1.33 1.27 1.21 1.16 1.27 1.21 1.31 1.12 1.06 1.23 1.17 1.21 1.11 1.31 1.29 1.22 1.22 2 2 1.24 1.10 1.04 1.22 1.21 1.19 1.20 1.36 1.31 1.23 1.20 1.30 1.12 1.16 1.19 1.20 1.24 1.21 1.39 1.31 1.23 1.10 1.26 1.07 1.09 1.14 1.06 1.17 1.18 1.31 1.29 1.07 1.05 1.25 1.10 1.03 1.09 1.08 1.11 1.16 1.30 1.23 1.07 1.02 1.22 1.09 1.01 1.09 1.11 1.05 1.07 1.36 1.20 1.10 1.08 1.25 1.08 1.02 1.09 1.04 1.10 1.06 1.35 1.27 F N F N F N F N F 1.11 1.10 1.27 1.19 1.19 1.17 1.38 N F N F 1.35 i N = No segments frozen at center of fruit; F = one or more segments frozen at center of fruit. In either case, however, the fruits may or may not have been frozen in one or both ends. 2 Plot picked by mistake. ^ Not enough frozen fruit to insure significant results. [26] 2.0 1.5 PLOT A \ ' „'' >.-T^ :rrrI:7 ^' " "~'"*^.r\ 1.0 2.0 PLOT D Z LU o 1.5 \\ "s \ \ \ \ LU n 1.0 \*' * i:5r ^: 1 h- PLOT E o OT 20 < 2 ,.5 o < \ v^r v ~'*-*?r- . LU 1.0 PLOT F VALENCIA ORANGE 2.0 h v NONFROZEN s \ : ^ — - FROZEN 1.5 \:;\. n \\. ^ — ::; — :r ^ : _- ^,_^=:=^^ t 1.0 ^'.~"' 28 FEB 14 28 MARCH II 25 APRIL 9 23 MAY 6 20 JUNE 5 18 JULY I 15 29 AUGUST 12 26 10 SEPT OCT SAMPLING DATES-1949 Fig. 14.— Free acids (as citric) in the juice from nonfrozen and frozen Valencia oranges. (See table 8 for these and other values.) stylar end was much greater for Plot A (645) than for Plot E (331). The con- centration of soluble solids is normally greater in the stylar end than in any other portion of the mature and nearly mature Valencia orange. At the time these fruits were frozen (December or early Janu- ary), they were so young that the con- centration of soluble solids in the stylar end was about the same as, or even less than, that in other portions of the fruit. The greater injury, however, in this por- [27] tion of the fruits from Plot A may have prevented the usual excessive accumula- tion of soluble solids in the stylar ends as the fruits matured. Plot F (fig. 13) shows one instance in which the concentration of soluble solids was higher in the frozen fruits than in the nonfrozen. In Plot D, the concentration of soluble solids in the frozen fruits on February 28 was exactly the same as on October 10 (9.23 per cent). Table 7 shows a similar trend in the nonfrozen fruits from Plot G. The concentration (11.23 per cent) on the last sampling date was only slightly higher than on the first sampling date ( 10.91 per cent) . As Tables 5 and 6 show that the amount and per cent of juice increased, Table 7 and Figure 13 continue the evidence that there was a general tendency for the frozen fruits to recover. free acids (as citric), — As a rule, the differences between the total amounts of free acids in the nonfrozen and frozen fruits were not so great as those between the amounts of soluble solids. For ex- ample, in Plot A, on August 29, the concentration of soluble solids in the non- frozen fruits was 26 per cent higher than that in the frozen fruits (table 7, fig. 13) , while in Plot E, on April 11, the concen- tration of acids in the nonfrozen fruits was only 13 per cent higher than that in the frozen ones (table 3, fig. 14) . These two examples are the extremes for soluble solids and acids for all plots. Table 3 and Figure 14 show not only that the fluctua- tions in amounts of acids were small, but also that there was relatively little de- crease in the per cent of acids in the juice from both nonfrozen and frozen fruits after April 25. The table and the figure also show that, for some of the plots, the free acids were lower on April 25 than they were for several weeks or even months later. To illustrate: The acid values for the juice from nonfrozen fruits from Plots A and F were lower on April 25 than they were on any of the following dates until September 12. On a few dates in the latter part of the season, the amounts of acids in the frozen fruits ex- ceeded those in the nonfrozen, as indi- cated by the crossing of the curves, in Figure 14. Sugars. — The trends for the total sugars (table 9 and figs. 15 and 16) were similar to those for soluble solids. Such a similarity would be expected since ap- proximately 85 per cent of the total soluble solids is composed of sugars— at least in fruits that are mature or nearly mature. There were fluctuations but, in general, the percentage of total sugars in the juice increased from the time of the first tests, on February 28, until the first or middle of August when it began to de- crease in both the nonfrozen and frozen fruits. While the total sugars were less in the frozen fruits than in the nonfrozen, their increase was similar as the season advanced. Table 9 also shows that the trends for the concentrations of total sugars in the nonfrozen fruits from Plots B, C, G, and H were similar to those shown in Figure 15 for the nonfrozen fruits from Plots A, D, E, and F. The concentrations of reducing sugars remained approximately constant, or even decreased, from February 28 until early June in the four plots represented in Figure 16. This was especially true for the frozen fruits. The same may be said of the reducing sugars from the nonfrozen and frozen fruits from Plot B and the non- frozen fruits from Plots C, G, and H (table 9). The sucrose values were usually at a maximum from early May until Septem- ber when, in some cases, they decreased. The ratio of reducing sugars to sucrose was highest in the first few tests and, in some instances, in the last two or three tests. The general trends shown for the sugar and also for the soluble solids are, no doubt, closely related to the physiological changes which occurred in the fruits as [28] TABLE 9 — Sugars in Juice of Nonfrozen and Frozen Valencia Oranges ALL FIGURES ARE PER CENT Plot Sugars Condition of fruit Feb. 28 March 14 March April 11 April 25 May May 23 June Reducing Sucrose. . Total... Reducing Sucrose.. Total. . . . Reducing Sucrose.. Total. . . . Reducing Sucrose. . Total. . . . Reducing Sucrose . . Total... Reducing Sucrose . . Total... Reducing Sucrose . . Total. . . . Reducing Sucrose . . Total. . . . N 1 F i N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F N F 4.80 3.78 1.09 1.38 5.89 5.16 5.18 5.02 0.86 1.17 6.04 6.19 5.57 4.24 0.49 1.38 6.06 5.62 5.06 4.42 1.90 1.30 5.96 5.72 4.84 4.64 1.06 1.18 5.90 5.82 4.26 3.88 1.21 1.59 5.47 5.47 5.47 5.23 1.14 1.07 6.61 6.30 5.22 4.78 1.02 1.23 6.24 6.01 4.74 3.93 1.47 1.37 6.21 5.30 4.99 4.68 1.48 1.67 6.47 6.35 4.99 4.43 1.18 1.40 6.17 5.83 4.79 4.73 1.17 0.82 5.96 5.55 5.08 4.57 1.45 1.19 6.53 5.76 4.46 4.36 1.25 1.18 5.71 5.54 5.20 5.03 1.27 1.11 6.47 6.14 5.37 4.89 0.77 1.08 6.14 5.97 5.23 4.49 1.21 1.36 6.44 5.85 4.98 4.89 1.75 2.07 6.73 6.96 4.78 4.47 1.50 1.42 6.28 5.89 4.77 4.17 1.35 1.49 6.12 5.66 4.71 4.62 1.73 1.59 6.44 6.21 4.55 3.83 1.75 2.08 6.30 5.91 4.94 4.78 1.26 1.24 6.20 6.02 5.10 4.57 1.32 1.65 6.42 6.22 5.00 4.31 1.81 1.96 6.81 6.27 4.85 4.31 2.69 2.44 7.54 6.75 4.83 4.25 1.82 1.89 6.65 6.14 4.36 3.93 1.95 2.00 6.31 5.93 4.68 4.17 1.68 2.14 6.36 6.31 4.44 3.61 2.39 2.50 6.83 6.11 5.18 4.64 1.41 1.81 6.59 6.45 5.01 1.66 6.67 4.83 4.31 1.82 1.96 6.65 6.27 5.24 5.43 2.01 1.83 7.25 7.26 5.31 a 1.87 3 7.18 4.25 4.14 2.04 1.57 6.29 5.71 5.07 4.57 1.95 2.03 7.02 6.60 4.48 3.84 2.48 2.17 6.96 6.01 4.64 4.32 2.05 1.92 6.69 6.24 4.60 2.00 6.60 4.97 3.74 2.29 2.45 7.26 6.19 5.20 4.62 2.47 2.45 7.67 7.07 5.10 1.60 6.70 4.38 3.97 2.26 1.86 6.64 5.83 5.18 4.54 1.99 2.10 7.17 6.64 4.46 3.94 2.54 2.26 7.00 6.20 4.84 1.78 6.62 5.07 1.59 6.66 4.96 3.86 2.55 2.35 7.51 6.21 5.25 4.90 2.40 2.45 7.65 7.35 4.87 '2.04 6.9i 4.37 3.63 2.09 2.08 6.46 5.71 5.04 4.25 1.94 2.19 6.98 6.44 3.88 3.84 2.80 2.73 6.68 6.57 4.58 1.84 6.42 4.97 1.53 6.50 5.01 3.72 3.06 2.80 8.07 6.52 5.08 4.83 2.56 2.71 7.64 7.54 4.82 2.4i 7.23 4.59 4.20 1.98 1.93 6.57 6.13 5.17 4.53 2.36 2.35 7.53 6.88 4.88 3.77 2.66 2.93 7.54 6.70 4.52 2.20 6.72 4.78 2.23 7.6i 1 N — No segments frozen at center of fruit; F = one or more segments frozen at center of fruit. In either case, however, the fruits may or may not have been frozen in one or both ends. 2 Plot picked by mistake. 3 Not enough frozen fruit to insure significant results. [29] Table 9 continued on next page. TABLE 9 (Continued) — Sugars in Juice of Nonfrozen and Frozen Valencia Oranges ALL FIGURES ARE PER CENT Plot Sugars Condition June July July August August August Sept. Sept. Oct. of fruit 20 5 18 1 15 29 12 26 10 Reducing N 1 5.39 5.60 5.62 5.67 5.55 5.89 5.74 5.78 6.02 F 1 3.98 4.51 4.42 4.84 4.70 4.20 4.66 4.48 4.23 A Sucrose. N 2.78 2.80 2.90 3.37 3.11 2.74 2.72 2.53 2.67 F 3.08 2.74 2.71 2.78 2.84 2.48 2.68 2.35 2.70 Total .... N 8.17 8.40 8.52 9.04 8.66 8.63 8.46 8.31 8.69 F 7.06 7.25 7.13 7.62 7.54 6.68 7.34 6.83 6.93 Reducing N F 4.95 4.85 5.43 5.16 5.79 5.47 2 2 B Sucrose . N F 3.28 2.93 3.18 2.93 2.96 3.51 2 2 Total. . . . N F 8.23 7.78 8.61 8.09 8.75 8.98 2 2 Reducing N F N F N F 4.49 5.21 5.79 5.69 5.74 5.87 5.66 6.07 6.12 C Sucrose. 2.67 2.81 2.56 2.90 3.00 3.31 1.64 2.55 2.46 Total 7.66 8.02 8.35 8.59 8.74 9.18 7.30 8.62 8.58 Reducing N 4.46 4.43 4.98 4.50 5.14 5.14 5.32 5.14 5.04 F 3.99 4.03 4.42 4.27 4.51 4.47 4.48 4.10 3.98 D Sucrose . N 2.40 2.66 2.98 2.91 2.64 2.52 2.27 2.80 2.31 F 2.33 2.37 2.24 2.54 2.30 2.45 2.18 2.42 2.27 Total. . . . N 6.86 7.09 7.96 7.41 7.78 7.66 7.59 7.94 7.35 F 6.32 6.40 6.66 6.81 6.81 6.92 6.66 6.52 6.25 Reducing N 5.47 5.21 5.63 5.93 5.70 5.44 5.62 5.45 5.60 F 4.68 5.13 5.26 5.31 5.30 5.01 5.25 4.92 4.60 E Sucrose . N 2.92 2.76 2.67 2.52 2.91 2.85 2.58 2.56 1.97 F 2.72 2.58 2.77 2.42 2.72 2.72 2.37 2.47 2.01 Total. . . . N 8.39 7.97 8.30 8.45 8.61 8.29 8.20 8.01 7.57 F 7.40 7.71 8.03 7.73 8.02 7.73 7.62 7.39 6.61 Reducing N 4.94 4.69 5.00 5.17 5.11 5.17 4.97 4.96 5.25 F 4.51 4.28 4.11 4.52 4.62 4.92 5.06 4.36 4.26 F Sucrose. N 2.77 3.33 3.18 3.09 3.25 3.12 2.74 3.00 2.50 F 2.76 3.15 3.07 2.96 2.67 2.97 3.00 3.12 1.82 Total. . . . N 7.71 8.02 8.18 8.26 8.36 8.29 7.71 7.96 7.75 F 7.27 7.43 7.18 7.48 7.29 7.89 8.06 7.48 6.08 Reducing N F N F N F 4.46 5.08 4.89 5.41 5.02 5.06 5.31 5.23 5.40 G Sucrose. 2.56 1.96 2.46 2.49 2.82 2.90 2.48 2.57 2.58 Total. . . . 7.02 7.04 7.35 7.90 7.84 7.96 7.79 7.80 7.98 Reducing N F N F N F 4.62 4.86 4.90 5.39 5.31 5.58 5.14 5.08 5.48 H Sucrose. 2.62 2.47 2.64 2.50 2.56 2.79 2.53 2.70 2.30 Total. . . 7.24 7.33 7.54 7.89 7.87 8.37 7.67 7.78 7.78 1 N = No segments frozen at center of fruit; F = one or more segments frozen at center of fruit. In either case, however, the fruits may or may not have been frozen in one or both ends. s Plot picked by mistake. 1 Not enough frozen fruit to insure significant results. [30] J 8h < PLOT E J i I L j l I i l I i L J L PLOT F VALENCIA ORANGE NONFROZEN FROZEN J ' ■ L J l I L J L 28 14 28 II 25 9 23 6 20 5 18 I 15 29 12 26 10 FEB, MARCH APRIL MAY JUNE JULY AUGUST SEPT. OCT. SAMPLING DATES-1949 Fig. 15.— Total sugars in juice from nonfrozen and frozen Valencia oranges. (See table 9 for these and other values.) [31] PLOT F VALENCIA ORANGE NONFROZEN — FROZEN 28 14 28 FEB. MARCH II 25 APRIL 9 23 6 20 5 18 MAY JUNE JULY SAMPLING DATES-1949 I 15 29 AUGUST 12 26 10 SEPT. OCT. Fig. 16.— Reducing sugars in juice from nonfrozen and frozen Valencia oranges. (See table 9 for these and other values.) they increased in size and maturity. The irregular fluctuations which often oc- curred from test to test are attributed to soil and climatic conditions. Early estimates and final packout results — Valencia plots, — As already stated, estimates were made on the total amount of freeze injury in the fruits soon after they had been exposed to the freez- ing temperatures. The data in Table 10 show how accurate these estimates were. They also show how near two groups of inspectors came to agreeing on their esti- mates of freeze injury in the fruits at the end of the test period. The determinations on February 2 and October 13 were made in the field by packinghouse and field in- spectors; those on October 10 were made in the laboratory by the authors. With the exception of Plots C and D, the injury values showed a downward trend in pro- portion to the estimated injury on Febru- ary 2. The values found by the authors on October 10 are a little lower in each in- [32] stance than those found by the inspectors on October 13, but the two groups of values are surprisingly close. The one ex- ception is for Plot D, but even this differ- ence is no greater than some of those found by the authors in making succes- sive determinations on fruit samples from different plots as the season advanced (table 1, p. 11). In so far as the packout grades are concerned (table 10) , most of them agree very well with the first percentage esti- mates of freeze injury on February 2. There were two exceptions. Judging by the results from the other plots, it appears that the estimated amount of freeze injury in Plot C was too high, and in Plot D, too low. It is well known that, in general, the small fruits on a tree are more likely to be frozen than the large fruits. This is shown indirectly in Table 10. The fruits from Plots A, D, and E were of poor quality as a result of freeze injury. They were also somewhat smaller than the fruits from the other plots, as shown below : PORTION OF FRUITS THAT WERE SIZE 200 (2%" DIAM.) OR LARGER: Plot: A C D E F G H Per cent: 22 28 25 24 38 49 32 The average weight of frozen fruits from all plots was slightly less than that of nonfrozen ones, but since average sized fruits, instead of all sizes, were used in these tests, it is probable that the differ- ences in weight were caused by injury and drying in the frozen fruits rather than by differences in size. This is borne out by the fact that the frozen fruits contained less juice than the nonfrozen (tables 5 and 6, pp. 20 and 22). TABLE TO — Freeze Injury Determinations and Packout Grades of Fruit from the Plots 1 ALL FIGURES ARE PER CENT Freeze injury 2 Portion of fruit in each grade Plot February 2 October 10 October 13 Sunkist Choice Orchard run Juice fruit (frozen and small sizes) No. of packed boxes A 60 51 35 60 20 18 29 7 27 32 17 4 3 33 12 45 36 20 9 12 68 70 65 63 21 18 25 19 61 74 85 38 11 26 14 10 8 17 62 C D 162 89 E 115 F 106 G 91 H 91 1 The values for Plot B are not given since the plot was picked by mistake before the end of the test periods and the fruit was not graded. 2 The freeze injury determinations on February 2 and October 13 were made in the field by the packing- house and field inspectors ; those on October 10 were made on samples brought to the laboratory for that purpose. [33 STORAGE TESTS Fruits for the storage tests were taken from three blocks of 50 trees each, adjacent to the plots of 25 trees each in three of the eight Valencia groves already mentioned. For the first storage test (March 9-April 7), 15 medium-sized fruits were taken from each tree— 750 fruits from each block of 50 trees. Each lot of 750 fruits was thoroughly mixed and then subdivided into five lots of 150 fruits. The subsequent treatment and test- ing of the fruits from block 1 will be described in detail. The fruits from the other two blocks were treated and tested in the same manner and at the same time. One of the lots of 150 fruits was di- vided into two groups of 75 fruits. One was tested for juice quantity and quality and the other for severity of freeze injury. The first tests were made on the day after the fruit was picked. The remaining four lots of 150 fruits each were put into a cold room at a constant temperature of 38° F and a relative humidity of 83 per cent. At the end of one week, lot 2 was removed from the cold room and tested in the same way as lot 1. At the end of two weeks, lots 3, 4, and 5 were removed from the cold room. Lot 3 was tested at once in the usual manner. Lots 4 and 5 were placed in the open in a very large room under conditions that more or less resembled those in a retail store. These two lots were tested at the end of one and two weeks, respectively. The minimum and maximum temperatures in the large room over the 2-week period (March 24 to April 7) ranged from 68° to 78° F. The relative humidities over the same periods ranged from 30 to 74 per cent, but stayed between 40 and 50 per cent most of the time. The second storage test (May 3 to June 2) was conducted in the same manner as the first, except that 1,000 instead of 750 fruits were picked from each of the three blocks of 50 trees. This permitted the use of 100 instead of 75 fruits for each weekly juice and freeze injury determination. The temperature (38° F) and relative humidity (83 per cent) in the cold room were the same as during the first storage test. In the large room, the temperatures ranged from 72° to 84° F. For two days during the first week, the temperature averaged about 81° F, but during the remainder of the two weeks, the range was from 75° to 78° F. The extremes of relative humidity were 20 to 38 per cent. On one day during the first week, the rela- tive humidity dipped from 30 to 20 per cent and back again over a 10-hour period. On the following day it dipped to 22 per cent over a 7-hour period. During the remainder of the two weeks it ranged, with no sharp breaks, between 32 and 38 per cent. Others who have made storage tests on frozen oranges have found that there was a decrease in volume of juice, a very slow rise, or none at all, in specific gravity, and a decrease in acids. In general, in these tests the responses of the fruits to the effects of the different temperatures and humidities in the cold room and in the large, well-aerated room (table 11) were not so clear-cut, but they were more or less masked by the natural differences that one would expect to find in the various fruit samples. Though less in quantity, the juice in the fruits that showed freeze injury at the center cut responded to the environmental condi- tions in much the same manner as did that in the fruits showing no injury at the center cut. For example, in the first storage test, the fruits from Plot D showed a general increase in soluble solids and a decrease in free acids from the first to the last (fifth) test, in both nonfrozen and frozen fruits. In the same storage test, the fruits from Plot F showed no clear-cut increase in soluble solids but did show a decrease in free acids. Both nonfrozen [34] TABLE 1 1 — Quality and Quantity of Juice from Nonfrozen and Frozen Valencia Oranges Kept Under Special Storage Conditions Plot Test no. First storage test — March 9 to April 7, 1949 Fruits, nonfrozen (N) and frozen (F)> (per cent) Juice Soluble solids (per cent) Acids (as citric) (per cent) Sugars (per cent) Per fruit (ml.) Per cent weight of fruit Reducing Sucrose Total N 9.51 1.95 4.17 2.20 6.37 41 46 1 F 33 (52) 9.23 1.95 4.06 1.75 5.81 33 36 N 9.57 1.95 4.82 1.92 6.74 46 45 2 F41(43) 9.17 1.82 3.76 1.89 5.65 35 38 D N 9.77 1.94 4.71 1.56 6.27 43 45 3 F 40 (57) 9.51 1.81 4.12 2.03 6.15 40 42 N 10.11 1.86 4.89 1.14 6.03 43 47 4 F 32 (45) 9.71 1.71 4.38 1.75 6.13 33 38 N 10.23 1.87 5.99 0.90 6.89 42 47 5 F36(64) 9.97 1.81 4.58 2.19 6.77 35 41 N 9.57 2.10 4.09 1.93 6.02 38 44 1 F 20 (33) 9.37 1.94 3.84 1.95 5.79 31 42 N 9.83 2.15 4.47 1.65 6.12 36 38 2 F 23 (44) 9.23 1.95 4.24 1.72 5.96 32 41 E N 9.91 2.00 4.85 1.70 6.55 38 46 3 F36(45) 9.91 1.96 4.99 1.40 6.39 34 43 N 10.17 2.12 5.14 1.41 6.55 37 45 4 F25(39) 9.91 2.05 4.98 1.41 6.39 27 35 N 10.43 2.00 5.15 1.63 6.78 40 48 5 F 23 (28) 9.91 1.76 4.66 1.84 6.50 29 37 N 9.91 1.82 4.22 2.08 6.30 46 49 1 F20(47) 8.63 1.59 3.08 2.32 5.40 30 35 N 9.91 1.87 4.68 1.84 6.52 46 46 2 F 15 (31) 9.83 1.79 4.18 1.76 5.94 36 43 F N 9.31 1.77 4.44 1.73 6.17 47 48 3 F9(28) 9.57 1.64 4.11 1.98 6.09 39 44 N 9.91 1.74 4.48 2.07 6.55 46 51 4 F 16 (25) 9.63 1.61 4.23 2.13 6.36 40 47 N 10.23 1.61 4.48 2.30 6.78 46 52 5 F 19 (25) 9.51 1.52 4.02 2.36 6.38 40 42 iThefi center of th represent tl well as in tl rst value given represents the percentage of fruits in the first lot that showed freeze i e fruit only; the tests were made on the juice from these fruits. The values given in le total percentage of fruits in the companion lot that were found to be frozen in otl le center ; thus the values represent the number of fruits frozen but not severity of in rijury in the parentheses ler parts as jury. Table 1 1 continued on next page. [35] TABLE 1 1 (Continued) — Quality and Quantity of Juice from Nonfrozen and Frozen Valencia Oranges Kept Under Special Storage Conditions Test no. Second storage test — May 3 to June 2, 1949 Plot Fruits, nonfrozen (N) and frozen (F) 1 (per cent) Juice Soluble solids (per cent) Acids (as citric) (per cent) Sugars (per cent) Per fruit (ml.) Per cent weight of fruit Reducing Sucrose Total N 9.91 1.33 4.38 2.34 6.72 56 48 1 F25(34) 8.31 1.26 3.35 2.19 5.54 34 37 N 9.23 1.30 3.96 2.06 6.02 49 45 2 F34(45) 9.23 1.28 4.08 1.83 5.91 42 41 D N 9.91 1.31 4.12 2.59 6.71 56 49 3 F25(41) 9.23 1.20 3.37 2.83 6.20 43 35 N 9.91 1.32 4.67 2.09 6.76 54 50 4 F 26 (42) 9.23 1.19 4.12 2.41 6.53 44 43 N 9.91 1.27 5.11 1.19 6.30 52 50 5 F32(44) 9.91 1.32 4.74 1.95 6.69 43 44 N 10.51 1.51 5.27 1.85 7.12 42 44 1 F 18 (34) 9.71 1.41 4.59 1.89 6.48 28 40 N 10.57 1.63 4.31 3.19 7.50 42 47 2 F 16 (20) 9.82 1.46 4.62 1.96 6.58 33 36 E N 10.23 1.60 4.27 2.60 6.87 42 46 3 F9(24) 10.23 1.56 3.91 3.00 6.91 33 33 N 10.57 1.53 5.18 1.86 7.04 45 48 4 F 25(37) 9.91 1.31 4.57 2.09 6.66 35 40 N 10.83 1.49 5.84 1.70 7.54 44 50 5 F30(33) 10.57 1.35 5.33 1.87 7.20 34 42 N 10.57 1.32 4.87 2.38 7.25 56 52 1 F 14 (21) 10.03 1.31 4.79 2.18 6.97 42 44 N 10.71 1.33 3.84 3.48 7.32 57 52 2 F 18 (30) 10.03 1.27 3.95 3.08 7.03 48 41 F N 10.57 1.38 4.13 3.24 7.37 54 55 3 F 15 (20) 9.82 1.28 4.05 2.88 6.93 44 43 N 10.71 1.31 4.76 2.72 7.48 58 54 4 F 13 (19) 9.71 1.27 3.83 2.58 6.41 29 47 N 10.97 1.30 5.27 2.33 7.60 55 55 5 F 14 (18) 9.91 1.19 4.41 2.25 6.66 43 44 1 The first value given represents the percentage of fruits in the first lot that showed freeze injury in the center of the fruit only; the tests were made on the juice from these fruits. The values given in parentheses represent the total percentage of fruits in the companion lot that were found to be frozen in other parts as well as in the center; thus the values represent the number of fruits frozen but not severity of injury. [36 and frozen fruits also showed a general increase in total sugars and in per cent of juice per fruit. Table 11 shows other, similar variations for all plots for both storage tests. Water- or X-ray-separated samples of fruit containing small, moder- ate, or large amounts of freeze injury (see following section) would, no doubt, have shown more marked differences as a re- sult of the storage treatment. It is also possible that greater differences would have occurred had the fruits been kept in the large, well-aerated room for more than two weeks. Two weeks should have been long enough, however, since there is usually less time than that between the removal of the fruit from the refrigerator car and its sale to the public. Neverthe- less, these results are of interest because they show the effect of the storage con- ditions on fruit direct from the grove. The minimum and maximum per- centages of fruits frozen, in the five samples for each plot, for both storage tests, were as follows: PERCENTAGE OF FRUITS FROZEN First storage test Second storage test (March 9-April 7) (May 3-June 2) Plot Min. Max. Min. Max. percent percent percent percent D 43 64 34 45 E 28 45 20 37 F 25 47 18 30 Although the percentages of fruits frozen were fairly high, the severity of freeze injury was not so great as these per- centages might indicate. Only 12 per cent of the 5,250 fruits used in the two tests had three or more frozen segments in one or more portions of the fruit. In so far as these tests were concerned, there was no indication that the freeze injury was more pronounced after the samples had remained for two weeks in the large, aerated room than it was when they were removed from the cold room. In only one instance was the greatest per- centage of frozen fruits found in the fifth, or last, sample. On the other hand, the minimum percentage of frozen fruits was found in three sections of the fifth sample (see table 11, E-5 (18) and F-5 (24) in first storage test, and F-5 (18) in second storage test) . The fifth sample included those fruits that had been in the large, aerated room for two weeks after being taken from the cold room. At the end of the first storage test there were no decayed fruits in any of the 24 storage samples. In the second storage test, eight fruits (out of 2,400) decayed- four with molds and four with Alternaria rot. The fruit was picked with clippers, but it was not washed, sterilized, or waxed before being stored. SEPARATOR TESTS Between August 24 and September 22, 1949, determinations were made on the relative quantities and qualities of juice from freshly picked Valencia fruits that had been separated into different lots ac- cording to the severity of their freeze in- jury (table 12 and fig. 17). Separations were made by a new X-ray grader or separator 3 that was being tested in one of the packinghouses (lots 1-9) ; by the often-used water separator (lots 10-18) ; and by hand, at the grading belt (lots 19- 24). In the first two methods, the fruits were divided into three lots: slightly (S) , moderately (M), and badly (B) frozen. The fruits picked by hand from the grad- ing belt were divided into only two lots, those slightly injured and those badly in- jured, as nearly as could be judged by appearance and feel. Each of the 24 lots contained 150 fruits, except lots 7 to 10, which had 170 fruits each. The specific gravity of the fruits was determined in all but six of the 24 lots, thus making it possible to figure the aver- 3 Developed and manufactured by the Au- tomatic X-ray Corporation of Los Angeles, California. [37] TABLE 1 2 — Characteristics of Juice from Valencia Oranges that Had Been Divided Into Different Lots According to Severity of Freeze Injury (The Separations Were Made by Three Different Methods) Fruit Juice Lot Extent of freeze injury Average specific gravity Portion of fruit Acids (as citric) (per cent) Sugars (per cent) no. Per fruit (ml.) By weight (per cent) By volume (per cent) Soluble solids (per cent) Reduc- ing Sucrose Total By an automatic X-ray separator little . . . medium much little . . . medium much little . . . medium much . 0.91 0.89 0.82 0.91 0.89 0.82 73 65 45 70 64 41 79 67 59 54 49 36 52 50 36 57 52 48 48 45 32 47 44 31 11.23 10.83 9.91 11.23 11.03 9.83 11.77 10.57 10.37 1.12 1.19 1.15 1.12 1.15 1.17 1.14 1.17 1.16 5.35 5.37 4.73 5.14 5.18 4.89 5.07 4.52 4.65 2.51 2.32 1.75 2.72 2.32 1.73 3.21 2.90 2.43 7.86 7.61 6.48 7.86 7.50 6.62 8.28 7.42 7.08 By a water separator 10 11 12 13 14 15 16 17 18 little . . . medium much little . . . medium much little . . . medium much . 93 89 81 94 92 86 66 54 35 70 55 38 67 52 32 54 46 40 56 52 39 56 54 38 51 45 31 52 45 33 10.31 9.57 9.71 12.23 12.51 12.51 11.31 11.96 11.03 1.19 1.21 1.28 1.08 1.19 1.31 1.08 1.07 1.08 5.01 4.42 4.49 6.13 5.93 5.90 5.27 5.38 4.87 2.19 2.13 1.84 2.41 2.76 2.39 2.67 2.90 2.42 7.20 6.55 6.33 8.54 8.69 8.29 7.94 8.28 7.29 By hand, at grading belt 19 little 94 78 58 53 11.23 1.08 5.35 2.58 7.93 20 much 93 70 55 51 10.17 1.10 4.98 2.13 7.11 21 little 90 66 52 46 10.63 1.08 5.33 2.15 7.48 22 much 88 59 46 40 9.71 1.02 4.50 2.20 6.70 23 little 90 69 52 45 12.17 1.34 6.10 2.35 8.45 24 much 88 66 49 44 10.57 1.22 4.95 2.21 7.16 [38] or < 3 _i < l- o H 1 i i 1 i CO Q z 00 U> -I o {/) UJ _i m z> _i CO 2 (/> o en _i < m o 2 in >- < 2 or i en x D O O 2: a 73 a> «« o s * 7. .t: -Q 3 D f w o »— v -' _c d -±= a> S_8 E 2 o) g **" .E > S TJ *0) X E ° — 0> v. T3 a o o no o ill £ o ^ SS » o >..E ai 1i 8 ° > i ID ° I ol I '. s. & : l*N D V