CHEMICAL AND PHYSICAL CHANCES OF BLUEBERRY FRUIT ASSOCIATED WITH RIPENING AND DETERIORATION By Richard Earl Woodruff AN ABSTRACT Submitted to the School for Advanced Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1959 Approved / Abstract Richard Woodruff 1 About one half of the blueberries harvested in Michigan go to fresh market outlets. Frequently, considerable losses due to deterioration of the fruit in transit and in the markets are encountered and these losses often can be attributable to overripe berries within a package, therefore, a knowledge of the proper time to harvest the ripened fruit would be an important asset to the blueberry industry. Chemical changes and changes is physical'characteristics due to chemical changes have been used as harvesting standards for other fruit so it would seem likely that one or more similar changes in blue­ berries could be adapted as a harvesting standard. For this reason, the initial step in this research was to-determine the changes In organic and inorganic fruit constituents during the ripening phases of fruit development. The second step was to use this knowledge as a basis for devising a rapid test suitable for field application as a means of determining the proper time to harvest blueberries for optimum dessert and keeping quality. During the first year of this study Jersey blueberry fruit on 18 uniform bushes of a commercial plantation were tagged at the time of red -color development in the skin. These fruit were harvested at 3-4 day intervals for a period of 20 days after red coloration to provide fruit of known and varying degrees of ripeness. The harvested fruit were quickly frozen, held at -5° F. until all harvests were completed, and finally lyophillized In preparation for the determination Richard Woodruff 2 of chemical constituents on a dry weight basis. Chemical analyses of the Jersey blueberry fruits of known and uniform physiological age showed changes with ripen­ ing as follows: (1) sugar content Increased for 9 days after red color formation and then remained constant, (2) titrat- able acid content decreased continually and the pH Increased continually as ripening progressed, (3) intensity of pig­ mentation increased the first six days following red coloration and then did not change, (4) soluble pectin contents decreased continually and', associated with this, the pectin methyiesterase acitivity increases, (5) starch, acid hydrolyzable polysaccharides, ether soluble material, lignin, and cellulose did not change markedly, and (6) changes in mineral constituents were relatively small and inconclusive with ripening. Sugar acid ratios increased with ripening and there was a positive linear correlation between this ratio and ripening of the fruit. This relationship was substantiated by repeat­ ing the test the following year for Jersey blueberries using the same bushes. Fruit of the Rubel variety was also harvested at known stages of ripening. The positive linear correlation of sugar-acid ratios to the degree of ripeness of the fruit held true for both varieties. The change of the sugar-acid ratios of the fruit with advancement of phyBiological age was outstanding and most likely of practice-1 significance for a measurement of ripening. Richard Woodruff 3 Since the inital data indicated that the sugar-acid ratio was a promising index of ripening, five plots of 20 Jersey bushes were used to relate the sugar-acid ratios of the fruit to their shelf life after harvest. The five plots selected were in commercial plantations of varying ages in western Michigan near Bangor, Grand Junction,Lacota, Allegan, and Holland, The different locations which extended in a north-south direction for about 100 miles, provided a sequence of initial harvest dates. The harvests which started July 31 and continued to August 31, consisted of 5 pickings of each plot at intervals oi four days. Ripeness of the fruit was varied by harvesting one set of four bushes of each plot at each harvest date. No fruit were harvested from a set of bushes prior to the designated time of harvest. At this time all fruit v^inich were clue in color were picked from clusters at random from the four bushes to fill eleven pint boxes. Ten of these pints were used for storage tests and one pint was frozen for chemical analysis# The sugar-acid ratios for the fruit harvested over a period of 20 days which initially contained fruit oi variable degrees of ripeness and which contained wider ranges oi ripeness as harvests progressed, were correlated with the percentage of oreaxdown of the fruit in storage. Increases in the accumula­ tion of ripening were acomoanied oy increases in the sugaracid ratios and the percentage breakdown in storage. It was found that the keeping quality of Jersey olueberry fruit Richard Woodruff 4 was dependent upon the degree of ripeness, which in turn could be measured by a sugar-acid ratio. A soluble solids- acid ratio was equally reliable as a measure of ripeness as the sugar-acid ratio. It was found that pH gave a reliable estimate of the acid content of the fruit and that a hand refractometer measurement of soluble solids served to measure the percentage sugar content. Since soluble solids and pH can be measured quickly in the field, it would appear that a soluble solidsacid ratio could serve as a n •index for harvesting blueberries. Also it could be used to determine the lots of harvested fruit suitable for shipment, and possibly the period of time the fruit could be in transit and marketed without excessive deterioration. CHEMICAL AND PHYSICAL CHANGES OF BLUEBERRY FRUIT ASSOCIATED WITH RIPENING AND DETERIORATION By RICHARD EARL WOODRUFF A THESIS Submitted to the School for Advanced Graduate Studies of Michigan State U niversity of Agriculture and Applied Science in partial fulfillm ent of the requirem ents for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture 1959 ProQuest Number: 10008551 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10008551 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 IOKNOWLEDGMENT The author wishes to express his sincere appreciation to Dr. D. H. Dewey for his constant guidance, encouragement and aid throughout this study. The writer is also indebted to"Dr. H. M. Sell for his advice in carrying out the chemical analyses, for assistance in editing the manuscript, and services on the guidance committee; to Drs.'A. L. Kenworthy and L. M. Mericle for assistance in editing the manuscript and services on the guidance committee; and to Mr. 3. T. Bass and the staff of the Department of Agricultural Chemistry for carrying out the spectrographical analyses of the fruit. Appreciation is extended to the Michigan Blueberry G-rower's Association and to the many growers whose co­ operation made these experiments possible. TABLE OF CONTENTS PAGE I N T R O D U C T I O N ............................... 1 LITERATURE REVIEW 4 ................................ MATERIALS AND M E T H O D S ................................ 10 RESULTS .............................................17 D I S C U S S I O N ...........................................41 CONCLUSIONS SUMMARY . .................................... 53 ......................................... LITERATURE C I T E D .................................... 58 55 L IS T CF TABLES TABLE 1. Analysis of blueberry fruit for certain organic constituents. Jersey variety. (Percent dry weight) ........................... 2. Composition of blueberry fruit for certain ash constituents as associated with ripening. Jersey variety............................... 3. 4. PAGE 35 Sugar, acid, and sugar-acid ratios of Jersey and Rubel blueberry fruit at the different stages of ripening in 1958 on a fresh weight basis. ... 36 The relationship between sugar-acid ratios and breakdown in storage of Jersey blueberries. . . 40 5. A comparison of the linear correlation coefficients and standard errors for sugar-acid ratios, sugar content, and acid content with the percentage breakdown of Jersey blueberry fruit held 18 days at 40° F. and6 days at 75 F ...................... 49 6. A comparison of the linear correlation coefficients and standard errors for estimating sugar-acid ratios and soluble solids-estimated acid ratios with the percentage breakdown of Jersey blueberry fruit held 18 days at 40° F. and 6 days at • 52 75° F ................... L IS T OF FIGURES FIGURE 1* 2. 3. 4. 5. 6. 7. 8. The changes in reducing sugars, non-reducing sugar, and total sugars of Jersey blueberry fruit during ripening on a dry weight basis. PAGE . . 20 The changes in titratable acid content and pH of Jersey blueberry fruit during ripening on a dry weight basis. . . . ................. 23 The changes in starch and acid hydrolyzable polysaccharides contents, and ether soluble material of Jersey blueberry fruit during ripening on a dry weight basis. ............. 26 The changes in lignin and cellulose content of Jersey blueberry fruit during ripening on a dry weight basis. ........................... 28 The changes in soluble pectin content and pectin methylesterase activity of Jersey blueberry fruit during ripening on a dry weight basis. . . 31 The changes in percentage transmission of light attributable to anthocyanin content in Jersey blueberry fruit during ripening................. 33 Sugar-acid ratio changes of Jersey and Rubel blueberry fruit during ripening................. 38 The linear correlation of sugar-acid ratios of Jersey blueberry fruit with the percentage breakdown in storage for 6 days at 75° F. and 18 days at 40° F. ........................... 48 1 INTRODUCTION Knowledge of the proper time to harvest the ripened fruit would be an important asset to the blueberry industry. Presently, each grower on the basis of his personal experience determines the time to pick his fruit according to fruit characteristics such as size of the berries, sweetness to taste, and firmness of the flesh. Individual variations of judgement and opinion of ripeness result in large differences in quality of the fruit harvested from different plantations. About one half of the blueberries harvested in Michigan go to fresh market outlets. Frequently, considerable losses due to deterioration of the fruit in transit and in the markets are encountered and these losses often can be attributed to overripe berries within a package. The overripe berries are subject to breakdown which may cause the other berries in the container to become moistened with juice or they may decay so as to make the berries unattractive, off-flavored, and less marketable. The. presence of overripe fruit in fresh market packs can be attributed to the lack of standardization in determining the proper time of harvesting. Therefore, an objective test to measure the ideal stage of ripeness for optimum dessert quality and maximum market and storage life would be desirable. There are numerous fruit properties to consider in choosing 2 a suitable index of maturity cr rioenin;;;. Many of these characteristics afiect edible quality; thoy include flesh and skiii texture, sweetness or tartness, and psychological considerations -such as color, size, and freedom of defects. Frequently, the eating quality of fresh product must be partially sacrificed to provide a marketable product which may be handled without damage, stored for a reasonable period, and remain free of physiological or pathological disorders until the consumer has had an opportunity to utilize the product. The maturing fruits of the highbush blueberry rapidly change in color from green to red and then to dark blue. Once the skin of the berries becomes completely blue in color it .is impossible to observe if the berries have ripened adequately to be harvested. Since the position of the berries on the panicle is no indication of the degree of maturity there is no set pattern for harvest of the fully colored berries. All blue colored fruit are picked and, therefore, all degrees of ripeness are included in the yield. A harvesting standard would need to measure the degree of ripeness of blueberries- which are quite lacking in uniformity of ripeness, and still provide a guide to avoid except ive quantities of overripe fruit. The terms mature and rice are not clearly definitive in common usage for describing fruit condition. With blue­ berries it would seem best to aoply the term maturation to 3 all phases cf development cf the berry'from fertilization to senescence. Fruit growth from fertilization to rea color development cf the -kin may bo considered &'■ tue i;:.Lia.ture stage or maturation, and red coloration to senescence may be considered the mature stage. Changes taking place during the latter stage may be considered as ripening. Within the mature stage, sour berries that lack blueberry flavor may be unripe, the fruit may be considered as rioc when -maximum dessert quality has been attained, and overripe / when the fruit becomes flat in taste cr post esses tin undesir­ able texture or appearance due to aging. Chemical changes and changes in physical characteristics attributable to chemical changes have been used as harvesting standards for other iruit so it it probable that one or more similar changes in blueberries could be adanted as a harvest­ ing standard. For this reason, the initial step in this research was to determine the development or degradation of organic and Inorganic fruit constituents during the ripening phases of fruit development. The second step was to de­ termine the possible use of this knowledge as a basis for devising a rapid test for determining the proper time to harvest blueberries for optimum dessert and keeping qua lity. Such a rapid test would be desirable for use under field conditions. 4 LITERATURE REVIEW Numerous experiments designed to measure and define the "best stage of maturity or ripeness for harvesting horticultural crops are described in the literature. Few, however, have dealt with the blueberry and relatively little information is available describing the quality factors and how they are affected by physical and chemical changes cf the fruit as ripening progresses. Recommendations for harvest are limited and vague with respect to the condition of the fruit. Bailey et a l « (1939) made the following statement regarding the harvesting of blueberries: nor too ripe. blue color. "They must be neither too green The stem end of ripe berries has a dark, rich, A reddish tinge there indicates immaturity. Underripe fruit is sour and lacks blueberry flavor. should be done every six or seven days. than this, Picking If done more often too many underripe berries are picked." Little was added by the recommendations of Slate and Col_ison (1942), except that overripe berries should be excluded from the harvests, but they made no suggestion as tc the identifying characteristics of overripeness. The commonly used maturity indices are summarized by Shoemaker (1955). They include subjective guides such as aroma, taste, changing of the color of the stems from green to brown, shriveling ci the stems, ease with which the berries separate from their stems, freedom of the seeds from the nip, 5 and color of seeds. Objective tests, where applicable, are more suitable for general use. Those listed as possible Indices are size, sugar and acid content, the sugar-acid ratio, changes in viscosity cf the juice, and changes in texture of the pulp. Objective inuices discussed by Smccn and heubert (1950) as possibilities lor apples are flesh pressure, the time interval from full bloom, and starch content of the fruit. Uhe (1957) presented data shelving a definite correlation between fruit size and sugar and acid content of the Jersey variety of blueberry. Sugar content increased with increased berry size, and acid content decreased with increased berry size. Various fertilizer treatments did not significantly influence the sugar or acid content of the berries. Berries picked at the end of the season were less acid than those picked at the beginning oi the season and sugar content in­ creased with later picking. shuts^ et a l . (1956 )» however, indicated that the soluble solids content ox ripe berries cf the Dixi, Pemberton, Atlantic, m u Pioneer varieties decreased as the harvest season progressed. For a given variety, early ripening berries were sweeter than those ripening later. Bunemann (1956) found th- t the soluble solids content cf blueberries increased as ripeness progressed. Bailin e r , et a l . (1955) reoort “d thau total yield in pounds per oush efxects soluble solids content of the blueberry fruit with soluble solids content decreasing as yield increased. 6 Caldwell (1934) found in oranges, gr^ oefruit, ap-de.: , strawberries, blackberries , ra;/oerries, eiderberrie s , pc-keberries, end cherries that the tc'tal titrate.die acidity increased as the fruit matured, attained a maximum about the time ripening began, and then decree sed as ripening proceeded. Hill (195b) found with raspberries that changes were generally uniform in titratable acid content and hydrogen ion concentration. of^y reached a maximum about toe o i m visible fruit pigmentation occurred : nd then de­ creased as ripening proceeded. He suggested these changes may account for the increased palatability cf berries between the time ox fruit pigmentation to iuii ri;xness. There is considerable evidence that au._ar anu acid ! changes can be used as me s.sure s cf ripening for other fruits. Soluble solids content has been resorted as a measure cf harvest maturity for cherries by Marshall (1954) and for grapes by Shoemaker (1955)- Soluble solids content of oranges, cantaloupes, melons, and pears are given as maturity standards in the Agricultural Code of California (1957). A maximum acid content of the juice serves as a maturity standard for pomegranates (Agricultural Code of California, 1957)• Sometimes a sugar-acid ratio gives a better measure­ ment of eating quality than either sugar or acidity alone. Harding et a l . (1940) reverted that the ratio cf total solids to total acid has been used as a maturity standard for oranges for many years. He suggested that a miniuium total 7 solids as well as a minimum total acid content be used as a maturity standard for Valencia oranges. Rygg and Getty (1955) found that the best maturity standard.for Karsh grapefruit was a ratio of total solids to total acid. They indicated, however, that discrepancies between this ratio and palatability made a better standard desirable. Winkler (1932) suggested that maturity related to palatability could be measured for table grapes using the degree Balling and the degree Balling-acid ratio. Amerine and Winkler (1941) concluded that the Balling-acid ratio was influenced by re­ gional and seasonal conditions, the size of the crop and the variety. Variety was of marked influence and seemed more important than other variables studied. Haller (1952) stated that soluble solids-acid ratios have been used as a maturity index for cantaloupes. Truscott and Wickscn (1954) found that juice viscosity of the fruit showed promise as a measurement for predicting the proper harvest dates for apples, peaches, and pears. Allen (1929) reported the results of studies of ripening changes for plums, pears, apricots, peaches, and no les. He concluded that softening of the flesh wes one of the most impcrtant changes taking place in deciduous fruit*. The knowledge thet the flesh of fruits soften during ripening h=.e stimulated the testing of various pressure devices for measuring fruit maturity. Haller (1952) concluded a ores sure test wee: the best approach to a maturity standard for reaches. 3 Pressure tests have been the most reliable and practical maturity teat for peart (A Lien, 1932). The Bcuycuccs- Mar shall (1931) small fruit fires sure tester was .successfully used by Bunemann (1956) to measure differences in flesh firmness of blueberries. He obtained measurable differences in pressure readings with blueberries of different decrees of ripeness which had been stored eight weeks. The time interval from full bloom has been recommended as a maturity index for apples by Haller and Smith (1950). However, an apolicatio d of a period of time from full bloom to harvest would be difficult with the blueberry since the blossoming period lasts two to five ween? in commercially grown highbueh varieties. Bailey (1947) reported that the time interval was too variable between season? to be cf practice 1 use as a maturity standard for blueberries.. Also Hlndle et a l . (1957) have reported that the time interval between blossom drop and fruit maturity was too variable to be used as a prediction of harvest time for blueberries. They also found no relations-hi time to maturity. between wood thicknees and Young (1952) found that the development of the blueberry fruit took place in three stages: stage I, rapid growth; stage II, very little increase ^n size; end stage III, rapid growth and ripening. Stage II was quite variable even between berries on a single plant, thus rendering a time interval for harvest maturity unreliable. Hindle et a l . (1957) also observed this growth pattern for 9 varieties cf blueberries. It is important that blueberries possess adequate market and storage life In addition to high dessert quality. The fruit should be left on the bush until it becomes ripe since the blueberry, like the grape, does not increase markedly in sugar content after harvest (Shutak et a l ., 1957)• These researchers showed that berries when ripened on the bush averaged 3*7 percent higher in soluble solids than berries ripened off the bush. Chandler (194-4) found that blueberries could be kept four to six weeks at 35°F. In sealed Jars provided they were firm, not overripe, and handled as little as possible. Bunernann et a l . (1957) found that blueberries harvested at three stages cf maturity defined as ripe, firm ripe, and hard ripe could be stored for two weeks without any marked changes from the original quality. The limited information presently available lor blue­ berries suggests th;- t measurement of chemical changes associated with ripening may serve as a guide for harvesting this fruit. Also the favorable results obtained In adapting chemical changes to harvesting standards with ether fruits indicate that they might be adaptable as a maturity index or standard for blueberries. 10 MATERIALS ADD METHODS The blueberry fruit obtained in the firot year of this study came from a commercial plantation of 20-year old .Jersey bushes near South Haven, Michigan. Fruit of known age in respect to riearning were assured by first removing all the berries -which were blue in color from 18 uniform-sized bushes so that only fruit which were red or green in color remained. Since this was shortly prior to the time cf a normal first commercial harvest, many fruit showed pigment development (red or blue) the,following day. These were then tagged and subsequently harvested over a period of time to p 1*0 vide fruit of known maturity or degree cf ripeness. The tagged fruit were picked at intervals of three or four days for a 20-day period. These harvests provided a range cf fruit maturity of the fruit from unripe to overripe. Four pints of berries were obtained at each harvest. The berries were picked into a container and randomly divided into four lots, and then sealed into separate plastic bags. Soluble solids readings -were taken in the field at the time of harvest with a Zeiss-Opton hand refractometer. Three determinations were made of the juice extracted from about 20 berries crushed in a milk filter disk. The fruit in the plastic bags was placed in a home freezer caoinet at approximately -5° F. within one half hour after harvest. 11 At the conclu'ion of the harvest season the berries were ground in the frozen state in a Waring blendor and then lyophillized to prevent chemical and enzymatic changes during drying. This method of drying, the fruit permitted enzymatic studies and prevented caramelization of the sugars. The lyophillized fruit was finally dried over phosphorous pentoxide at four millimeters pressure and room temperature in a Weber vacuum oven. The entire fruit was used for analysis without me king a separation of seed, skin,and flesh. A weighed ether soluble fraction was obtained from a o n e 'gram sample of dried blueberries extracted for 16 hours in a Soxlet extraction unit with absolute diethyl ether. After extraction the extractant was evaporated on a steam bath and then dried for four hours at 70° C. and four millimeters pressure over phosphorous pentoxide in a Weber vacuum oven. The original dry residue was prepared for carbohydrate analyses and analyzed for reducing sugars, non-reducing sugars, starch, and acid hydrolyzable polysaccharides by the pro­ cedures outlined by Sell e t ■a l . (1946). Acid hydrolyzable polysaccharides were determined from the acid hydrolyzable residue from the starch determinations:. Approximately one gram of dried fruit was extracted with 50 milliliters of SO percent ethyl alcohol for four hours on a Goldfisch apparatus end analyzed for cellulose by the method described by Phillips et a1 . (1945). The iignin 12 content was obtained according to the procedure cf Williams and Clmstead (1935) using about two grams of dried fruit and extracting with 80 percent ethyl alcohol for four hours on a Golafisch apparatus. Soluble po ctln content v;ae determined by a lightly modi!led procedure from the one described by Lawrence and Groves (1954)• 'Instead of repeated washing of the calcium pecrate precipitate by alternate centrifuging and decanting, as recommended, the calcium poctate precipitate wa~ transfered tc a tared filter paper. The precipitate wa. war. nod with hot wafer until free of chloride ions. The paper and centonto were then dried at 100c C. for 43 hours and wei tied. One gram of dried fruit was extracted with 30 milliliters cf water at 38° C. for one hour, filtered, nd the filtrate used for pectin metnyiesterase determinations (Ke rt e'sz , 153 7 )• A one gram sample cf dried fruit was used to determine .anthccysnin content. The procedure used"for extraction was described by Anderson (1923 )• The filtrate containing the pigments 'was made to 100 milliliters with water ana taen diluted to 200 milliliters with 0.1 molar citric SvCio and 0.2 molar disodium phosphate suffer solution, the pK adjustec. oc 3.0 w1th 0.1 molar solution o f sodium nyaroxido, a nd :hen made to 100 milliliters with water. Transmission wa^ measured in a Beckman W K-2 spectrophotometer at 500 millimicrons. Titratable acidity was round by tire procedure 13 described in 4*0.4.C. (1955). Water was added to a one gram sample in an amount calculated to be equivalent to re­ store the berries to a fresh weight basis and thoroughly stirred. The pH was measured initially and then the juice was titrated with 0.1 normal sodium hydroxide to a pH of 8 .1 . Some of the mineral constituents of the fruit, namely; calcium, magnesium, manganese, copper, iron, phosphorous, boron, and silicon, were determined by a modification of the method used by Perry et al. (1950), whereby a potassium sulfate-graphite buffer in powdered from was substituted for a 20 percent sodium nitrate solution. The same procedures and bushes were used for obtaining blueberries of known degrees of ripeness in 1958 as in 1957. However, in 1958 two pints of tagged fruit were picked at each harvest. The harvests were spaced four days apart and made for a period of 20 days. In addition, 15 bushes of the variety Rubel grown in the same plantation and of the same age as the Jersey bushes were tagged and harvested in a like manner. 411 berries were transported to East Lansing the same day they were harvested in an insulated food jar on dry ice, and then transferred to a freezer room and held at -5° F. until chemically analyzed. Since the 1957 data indicated that the sugar-acid ratio was a promising index of ripening, five plots of 20 Jersey bushes were used to relate the sugar-acid ratios of the fruit 14 to their shelf life after harvest. The five plots selected, were in commercial plantings of varying ages in viestern Michigan near Bangor, Grand Junction, Laccta, Allegan, ana Holland. The different locations, which extended in a north- south direction for* about 100 miles, provided, a sequence of initial harvest dates. The harvests, which started July 30 and continued to August 31, consisted of 5 pickings of each plot at intervals of four days. Ripeness of the fruit was varied by harvesting one set of four bushes of each plot at each harvest date. Ho fruit was .harvested from a set of ouches prior to the designated time of harvest. At this time fruit which was blue in color was picked from clusters at random from the four bushes to fill 11 pint boxes. Ten of these pints we re. used for storage tests and one pint was frozen for chemical analysis. The storage samples were transported to East Lancing the same day they were harvested and pla eed in controlled temperature rooms r l* i LO «H • '—1 o 00 I —I EH 03 r—4 o o o Vi t-H '4 o O M « O £: m M P4 < Q SB Eh PQ ■4 ei O _ O P4 fG o 3 &h a. • XU >H es H4 00 • r- o 03 • rH r- to • CO o co • to CO rH • 1 o •H -P CO Pi O i—1 o o T3 0 CG 03 i—1 CD j i o o o CD * to o (D • O Is• rO 00 CD • i—1 oo r~• CO to 03 Ob o r- lO • n4 to 1—1 LO lO O 9 to • CO 9 o r- rr• to CO cO • Ob ■to • iO to t3 • 'tr 00 CO • o r00 * to o o i—1 t'3 • H4 I '1 CO • o • CO LO ^t4 • CO H4 O 0 0 > > 0 0 rH rH LO rH 4 0 >> 0 Q to CO P4 4 OS > W O'! LO • tu o • 'b4 CO o • o W CO cd .H PQ H4 02 ♦ 03 to !> * Si4 i—I o to • CO 9 rto 00 H4 • CO LO CD to • to crH • LO to H4 CD • H4 LO to m • H4 o to • Ob LO o 03 • to o • CO 0 CD CO 6, and 9 days after red color form­ ation were similar and significantly less than the contents cf fruit of all other harvests. Although the starch content appeared relatively constant during the ripening period in Fig. 3, the percentage starch content cf fruit harvested at 6 days after rod coloration was significantly less than the percentage starch content of fruit harvested at all other times' except at 0 days. Fig. 4 shows that the cellulose content decreased slightlv U W U with progression of ripening during the first 9 days then held constant for the remainder cf the harvesting period. The content at 9, 12, 16, and 20 days was significantly lower than at 0 days after red coloration. Farmed changes in lignin content occurred with ripening, (Fig. 4). Lignin content of the first harvest was significantly 25 Fig. 3 The changes in starch and acid hydrclyzable poly­ saccharides contents, and ether soluble material cf Jersey blueberry fruit during ripening on a dry weight basis. £6 8 7 Starch P ER C E N TA G E 6 5 Acid hydrolyzable polysaccharides 4 3 Ether soluble fraction 2 0 20 DAYS A F T E R RED COLORATION 27 Fig. 4-. 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