EFFECT OF SUB-FREEZING TEMPERATURES ON COMPONENT PARTS OF CITRUS FRUITS WITH PARTICULAR REFERENCE TO THE PECTIC CONSTITUENTS1

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1 ROUSE, ATKINS, MOORE: PECTIC STUDIES 295 believed t be due t the fact that many factrs, such as fruit quality, extractin and finishing prcedures, il cntent and thers, influence the flavr f range cncentrate. These ther factrs may be f equal r greater imprtance t flavr quality than that f the xygen cntent and, therefre, prevented any relatinship between xygen cntent and flavr frm becming ap parent. Relatively high xygen cntent was fund in the nly 4 prducts that were graded "pr" in flavr because f the presence f COF r "xidized" ff-flavrs. Acknwledgments The authr desires t thank Dr. J. Allen Brent f the Minute Maid Cmpany, a Divisin f the Cca-Cla Cmpany, fr supplying the curve fr cnversin f the percentage f xygen, as read n the Zermatic ph meter, t milliliters f xygen per 100 grams f cncentrate. Appreciatin is expressed t all f the cm panies which supplied the samples f frzen cn centrated range juice used in this investigatin and als t the persnnel f the U.S.D.A. Agri cultural Marketing Service, Winter Haven, Flr ida, fr their aid in the cllectin f these samples. The assistance f Mr. R. W. Barrn, wh made the viscsity determinatins, and that f the taste panel is hereby acknwledged. The members f the taste panel were G. E. Alberding, R. W. Barrn, Luise Cherry, M. H. Dugherty, E. C. Hill, M. D. Maraulja, S. K. Lng, R. W. Olsen, Rger Patrick, and F. W. Wenzel. LITERATURE CITED 1. Air Reductin Sales Cmpany Nitrgen treat ment f frzen range juice cncentrate. Technical Data and Prcess Bulletin ADE pp. ' 2. Blair, J. S., Edith M. Gdar, H. G. Reinke and J. R. Marshall The "COF effect" in frzen citrus prducts. Fd Technl. 11, Harwell, Thurstn W Flavr retentin f range juice. Transactins Citrus Engineering Cnference, Fla. Sectin, Am. Sc. Mech. Eng. 7, Olsen, R. W., E. L. Mre, F. W. Wenzel and R. L. Huggart Oxidized flavrs in frzen citrus cncen trates. Research reprt at Sixth Annual Citrus Prcessrs' Meeting. Flrida Citrus Experiment Statin, Lake Alfred, Fla. Oct Tressler, Dnald K. and Maynard A. Jslyn Fruit and Vegetable Juice Prcessing Technlgy. The Avi Publishing Cmpany, Inc., Westprt, Cnnecticut PP. 6. Unin Carbide Develpment Cmpany Flavr retentin prcess. U. S. Patent 2,911, Webster, Rbert C Nitrgen treatment as a means f extending shelf-life f chilled and canned single strength range juice. Transactins Citrus Engineering Cnference, Fla. Sectin, Am. Sc. Mech. Eng. 6, Wenzel, F. W The arma and flavr f Flrida range juices and cncentrates. Sympsium n Vlatile Fruit Flavurs. Bern, Switzerland. Internatinal Federa tin f Fruit Juice Prducers. Reprts f the Scientific Technical Cmmissin. Juris-Verlg and Buchdruckerei Zurich, Switzerland. 9. Wenzel, F. W., E. L. Mre and R. W. Olsen Factrs affecting the flavr f frzen cncentrated range juice. Citrus Statin Mime Reprt Research reprt at Eighth Annual Citrus Prcessrs' Meeting. Flrida Citrus Experiment Statin, Lake Alfred, Fla. Sept. 26. EFFECT OF SUB-FREEZING TEMPERATURES ON COMPONENT PARTS OF CITRUS FRUITS WITH PARTICULAR REFERENCE TO THE PECTIC CONSTITUENTS1 A. H. Ruse, C. D. Atkins, and E. L. Mre Flrida Citrus Experiment Statin Lake Alfred The wintry blast that struck Flrida Decem ber 12, 1962 lasted thrugh the 14th, lwered the temperature t sub-freezing fr many hurs, and caused injury t bth citrus trees and fruit. Internal fruit injury resulting frm sub-freezing temperature is imprtant t the prcessr be cause f its adverse effect n quality and yield f extracted juices. Many desirable physical and chemical characteristics f citrus juices depend lcperative research f the Flrida Citrus Experiment Statin and the Flrida Citrus Cmmissin. Flrida Agri cultural Experiment Statins Jurnal Series N upn the pectic cnstituents in the varius cm pnent parts f the fruit. T what extent cld injury affected the cmpnent parts will be dis cussed in this paper. A number f investigatrs (1, 3, 11, 12, 13) have reprted the effect f freeze damage n clr, sugar cntent, acid, specific gravity, ph, flavnids, and flavr f citrus juices. Bissett (2) cnducted studies n varius prcessing prce dures and presented the characteristics f range cncentrates prepared frm several varieties f ranges which had been damaged in the freezes f the seasn. Als, fllwing the severe freezes f the citrus seasn, Ruse et al. (8) presented infrmatin n the pectic changes and pectinesterase (PE) activity ccurring in the juices frm sund and freeze-damaged Pine-

2 296 FLORIDA STATE HORTICULTURAL SOCIETY, 1963 apple and Valencia ranges and seeded grape fruit. Mre et al. (7) btained infrmatin n the physical stability f cmmercial cncentrates made after the December 12, 1957 freeze. The bjective f this investigatin was pri marily t gather infrmatin cncerning the effect f sub-freezing temperatures n the pectic cn stituents in cmpnent parts f Pineapple ranges and Silver Cluster grapefruit. Changes in weight, ttal slids f whle fruit, percentage by weight f the cmpnent parts, sluble slids, acid, and ph f the juices were als determined. Crystals pssessing a bitter taste were islated frm fr zen Pineapple ranges and phtgraphed. Experimental Prcedure Preparatin f samples. Pineapple ranges grwn n rugh lemn rtstck were picked the afternn f December 12, 1962 prir t the cld blast which struck Flrida that night. This lt f ranges was the cntrl. Oranges were picked frm the same tree each week fr a perid f eight weeks fllwing the freeze. Each lt f ranges was washed, dried, and separated by hand int peel, seeds, and pulpy juice. The pulpy juice cnsisted f membrane, juice sacs, and juice which had been cmminuted in a Waring blendr. The mixture was separated int juice and pulp by centrifugatin. The juice pre pared in this manner wuld cntain mre watersluble pectin than wuld nrmally be fund in that extracted by mechanical means. Silver Cluster grapefruit grwn n rugh lemn rtstck were picked the beginning f each mnth, starting in December 1962 and cn tinuing thrugh April 1, Separatin f the fruit int cmpnent parts was similar t that fr the Pineapple ranges except that the juice was expressed frm juice sacs by a Watsn- Stillman hydraulic press using 40 psig. Prcedures in preparing the cmpnent parts fr PE determinatins and fr alchl-insluble slids (AIS) were the same as described by Ruse et al. (9) fr Valencia ranges. Pectic fractins were extracted frm the AIS f the varius cm pnents. Methds f analysis. PE activity and the three pectic fractins were determined and re prted n dry-weight basis as previusly de scribed by Ruse et al. (9). Sluble slids f Pineapple range juice was determined as de grees Brix by refractmeter at 28 C. and f the grapefruit juice as degrees Brix by spindle at 17.5 C. Ttal acid as citric, ph, and ttal slids f the cmpnent parts were determined by cnventinal methds. Brix/acid ratis f the juices and ttal slids f the whle fruit were calculated. The latter was accmplished by using the percentage f each cmpnent in the fruit and the ttal slids f each cmpnent (data b tained but nt presented in this manuscript). Results and Discussin Bth the Pineapple range and Silver Cluster grapefruit trees frm which the fruit were picked and examined fr this study were frm Blck II at the Citrus Experiment Statin. The cntrl lts f fruit, picked prir t the freeze, were sund fruit, whereas fruit picked after December 14 were seriusly damaged by freezing (5). Mini mum temperature registered at the Citrus Ex periment Statin was 18 F., the mrning f December 13. Pineapple ranges. Sme general charac teristics f juices befre and after the December 1962 freeze are presented in Table 1. Ttal slids and degrees Brix increased during the six week perid f sampling, but decreased the eighth week. Quantity f acid definitely decreased dur ing this study resulting in a gradual increase in ph. The increase f Brix/acid rati (12.1 t 21.1) was much greater during this perid than is nrmally fund due t maturatin f the range (10). Weight and ttal slids f the average whle range (Table 2) were grams and 18.20%, respectively, in December and grams and 20.74%, respectively, eight weeks after the freeze indicating shrinkage and drying f the fruit. Pulp, which cnsisted f membrane and juice sacs, decreased t 29.1% f the whle range ne week fllwing the freeze, after which this cmpnent increased in six weeks t its highest level f 42.6% (Table 2). Juice cntent f the range increased slightly ne week after the freeze ( %) and then declined t 26.7% eight weeks later. Sund Pineapple r anges during the nrmal maturatin cycle d nt vary t this extent in either pulp r juice cn tent (10). The distributin f PE activity in the cm pnent parts is shwn in Table 3. The greatest increase f enzymic activity was in the pulp ( units) immediately after the freeze. Peel and juice generally increased in PE activity fr six weeks fllwing the freeze. Seeds ranged in activity frm 3.8 units in the cntrl lt t 2.0 units eight weeks after the freeze. Changes in the pectic fractins fr peel, pulp,

3 ROUSE, ATKINS, MOORE: PECTIC STUDIES 297 Table 1. Pineapple range juice analyses befre and after the December 1962 freeze Picking date Ttal slids Ttal acid Brix Brix/acid rati ph Cntrl, 12/12/62 12/21/62, 1 wk. 12/28/62, 2 wk. 1/11/63, it wk. 1/25/63, 6 wk. 2/ 8/63, 8 wk« lil lit U m it. it. 10 Table 2. Changes in whle fruit and cmpnent parts f Pineapple ranges Picking Whle fruit Cmpnent parts-$ date Av. wt.-g Ttal slids-^ Peel Pulp Seeds Juice Cntrl, 12/21/62, 12/28/62, 1/11/63, 1/25/63, 2/ 8/63, 12/12/62 1 wk. 2 wk. it wk. 6 wk. 8 wk Iit Ut 19.it8 21.itO it it.it U2.6 itll it.2 3*9 U.3 it.8 $ it3.it it 25.it 26.7 Table 3* Pectinesterase activity^ in cmpnent parts f Pineapple ranges (dry weight basis) Picking date Peel Pulp Seeds Juice Cntrl, 12/12/62 12/21/62, 1 wk. 12/28/62, 2 wk. 3/11/63, it wk. 1/25/63, 6 wk. 2/ 8/63, 8 wk. it it Pectinesterase activity measured as PE«u./g X and juice are presented in Fig. 1. Water-sluble pectin in the peel f the cntrl fruit (2.9%) did nt increase until the furth week (3.6%) fllwing the freeze, after which it declined t 2.1%. This pectic fractin gradually declined in the pulp frm 2.5 t 0.8%, whereas the watersluble pectin in the juice frm the frzen r anges was always less than that fund in the juice f the cntrl. Generally, the ammnium xalate-sluble pectin varied very slightly in the peel, pulp, r juice seriusly damaged by freezing. This further cnfirms a statement made by the authrs (8) after the freezes which stated that am mnium xalate-sluble pectin was nt greatly increased in range juice fllwing a freeze and in sme instances actually decreased. Prtpectin r sdium hydrxide-sluble pec tin, nt in sufficient quantity t be imprtant in juice, did shw a slight decrease in the pulp. This wuld cnceivably ccur during the nrmal maturatin cycle. Hwever, the peel shwed re cuperative pwer f this substance as indicated by the increase f prtpectin six and eight weeks fllwing the freeze. Fur weeks after the freeze this pectic fractin had decreased frm 5.7% in the peel f the cntrl fruit t 4.3% in that f the freeze-damaged ranges. During the sixth and eighth weeks, the prtpectin increased (Fig. 1) t 6.8 and 6.5%, respectively. Ttal pectin, the sum f the three pectic fractins, was in fluenced by that fractin which shwed the greatest change. Fr example, ttal pectin was lwered in the pulp because f the drp in watersluble pectin and the increase f ttal pectin in the peel was primarily influenced by the in-

4 298 FLORIDA STATE HORTICULTURAL SOCIETY, c hj 1.0 * 05 1 a. ("-~---x - - )_ B -O HgO-SOL. -D NO OH-SOL. -X TOTAL WEEKS AFTER FREEZE x _rt_ x^ A- 0 H20-S0L. X TOTAL n - A WEEKS AFTER FREEZE OH20-S0L. D A (NH4 )2C204 - SOL. DNaOH-SOL. X TOTAL WEEKS AFTER FREEZE Figure 1. Pectic fractins in cmpnent parts f Pine apple ranges befre and after the December 12, 1962 freeze. A Frm peel, B Frm pulp (membrane and juice sacs), and C Frm juice. crease in prtpectin. Bitterness appeared in the Pineapple range juice extracted three weeks after the freeze. A bitter cnstituent had been extracted frm the pulp f Califrnia Navel and Valencia ranges by Higby (6) wh islated and identified it as islimnin. Later Emersn (4) called the sle bitter principle frm pulp and juice f Navel ranges limnin and named a new bitter principle fr range and lemn seeds nmilin. The authrs fllwed the prcedure f Higby (6) using benzene t extract separately the mem brane, juice sacs, pulp and juice, and seeds f Pineapple ranges. After precipitatin with pe trleum ether, the crystals were purified by redisslving in a mixture f equal parts f alchl and benzene and allwed t recrystallize. Crys tals prduced frm, the fur cmpnents were bit ter t the taste. These crystals were nt identi fied but they were phtgraphed and are pre sented in Fig. 2. Benzene extracts made n the pulp f the cntrl lt f ranges yielded n crystals and the cncentrated extracts were nt bitter. Silver Cluster grapefruit The cntrl lt f grapefruit was picked December 3, The secnd picking f fruit was January 2, 1963, abut three weeks fllwing the freeze, and the juice had definitely decreased in ttal slids, degrees Brix, and acid (Table 4), while the Brix/acid rati and ph had increased. Fr the next tw mnths, the juice shwed little change. Hw ever, juice frm grapefruit picked April 1, again changed in the abve cnstituents with the Brix/ acid rati and ph increasing t 8.02 and 3.55, respectively. Average weight f the whle grapefruit in December was grams, in February it had decreased t grams, and in April increased t grams (Table 5). Fr the crrespnding mnths, juice cntent fllwed a similar pattern, 41.2, 33.1, and 38.3%. Ttal slids f the average whle grapefruit decreased frm t 14.89%. Als the amunt f peel in the fruit increased frm 24.6% in December t 33.4% in April, which was nt the nrmal pattern fr this cmpnent during a nrmal grwing seasn (10). Pulp was the nly cmpnent part f grape fruit which shwed definite change in PE activity as the result f the freeze (Fig. 3). The enzymic activity in the pulp prir t the freeze was units and cntinued t increase t units in April. This als is the ppsite f what happens t PE activity during a nrmal matura tin cycle (10).

5 ROUSE, ATKINS, MOORE: PECTIC STUDIES 299 Figure 2. Crystals, which were bitter t the taste, islated frm cmpnent parts f Pineapple ranges three weeks after the freeze f December 12, A Frm juice sacs magnified 430 times, B Frm membrane magnified 40 times, C Frm pulp and juice magnified 40 times, and D Frm seeds magnified 100 times. Again, pulp was the cmpnent f grapefruit in which pectic changes ccurred (Pig. 3) as the result f the freeze. Water-sluble pectin in the pulp was 4.8% in December, decreased slight ly t 3.8% in March, and increased t 7.0% in April. The quantity f ammnium xalate-sluble pectin in this cmpnent mre than dubled dur ing this perid, being 8.1% prir t the freeze and 19.4% in April. The insluble pectates and pectinates usually increase with the maturatin cycle f grapefruit but nt t this extent. Sdium hydrxide-sluble pectin r prtpectin was nt affected by the freeze and the slight variatin in this pectic fractin culd be indicated as nrmal. Table 1*. Silver Cluster grapefrait juice analyses befre and after the December 1962 freeze Sampling timewnnths Ttal slids % Degrees Brix Ttal acid % Brdx/acid rati ph December January February March April (cntrl) * *1 lltf l.ii

6 300 FLORIDA STATE HORTICULTURAL SOCIETY, 1963 Table Changes in whle fruit and cmpnent parts f Silver Cluster grapefruit Sampling Whle fruit Cmpnent parts-^ timewnnths Av«wt.-g Ttal slids-^ Peel Pulp Seeds Juice December January February March April (cntrl) U73.6 U72.U U17.9 1*37.0 1^ tf.6$ Ik. 89 2k U , h.2 U.3 U.I U U.I Ul Summary Pectinesterase activity, three pectic fractins, and ther characteristics were determined n cm pnent parts f Pineapple ranges and Silver Cluster grapefruit picked prir t and after the December sub-freezing temperatures. Ttal weight and juice cntent f Pineapple ranges began a gradual decrease after the freeze. Enzymic activity increased in peel, pulp, and juice. Water-sluble pectin definitely de creased in the pulp and the ammnium xalatesluble pectin varied nly slightly in the cm pnent parts. A significant increase in prtpectin which ccurred in the peel six and eight weeks after the freeze indicated recuperative pwer f this cmpnent t "firm-up." Bitterness appeared in Pineapple range juice extracted three weeks after the freeze. Crystals with a bitter taste were islated frm membrane and juice sacs and phtgraphed. Silver Cluster grapefruit decreased in weight and juice cntent fllwing the freeze but unlike ranges they again increased in bth f these CO O H20 SOL. A(NH4)2C204-S0L. DNaOH SOL. #PE ACTIVITY 200 g CO ffi IS 2 16 > I 00 S 8 O Q. a. DEC. JAN. FEB. MAR. APR. PULP Figure 3. Pectic fractins and PE activity in the pulp f Silver Cluster grapefruit befre and after the December 12, 1962 freeze.

7 HATTON AND REEDER: TOMATO BRUISING STUDIES 301 characteristics. Greatest changes in PE activity and pectin ccurred in the pulp and nt in the peel r juice. Of the pectic fractins, the quanti ty f ammnium xalate-sluble pectin mre than dubled during the examinatin perid. LITERATURE CITED 1. Barthlmew, E. T., W. B. Sinclair, and R. P. Hrspl Freeze injury and subsequent seasnal changes in Valencia ranges and grapefruit. Califrnia Agr. Exp. Sta. Bui Bissett, O. W Prcessing freeze-damaged ranges. Prc. Flrida State Hrt. Sc. 71: Chace, E. M. and C. G. Church Methds f detecting and measuring frst injury. Prc. Flrida State Hrt. Sc. 40: Emersn, O. H The bitter principles f citrus fruit. I. Islatin f nmilin, a new bitter principle frm the seeds f ranges and lemns. J. Am. Chem. Sc. 70: Flrida Citrus Cmmissin State f Flrida citrus fruit laws. Flrida citrus cde citrus fruit; when damaged r seriusly damaged by freezing. 6. Higby, R. H The bitter cnstituents f Navel and Valencia ranges. J. Am. Chem. Sc. 60: Mre, E. L., A. H. Ruse, C. D. Atkins, R. L. Huggart, and R. W. Barrn Cmparisn f the physical stability f sme cmmercial frzen cncentrated range juices packed after the December 12, 1957 freeze with thse packed during the seasn. Citrus Magazine 20: (7) 16-17, 20, Ruse, A. H., C. D. Atkins, and E. L. Mre Chemical characteristics f citrus juices frm freeze-damaged fruit. Prc. Flrida State Hrt. Sc. 71: Ruse, A. H., C. D. Atkins, and E. L. Mre Seasnal changes ccurring in the pectinesterase activity and pectic cnstituents f the cmpnent parts f citrus fruits. I. Valencia ranges. J. Fd Sci. 27: Ruse, A. H., C. D. Atkins, and E. L. Mre Pectin and pectic enzymes in the fruit and prcessed prd ucts f citrus. Flrida Agr. Exp. Sta. Prgress Rpt. 11. Webber, H. J., E. E. Thmas, H. D. Yung, and C. O. Smith A study f the effects f freezes n citrus in Califrnia. II. Changes that take place in frzen ranges and lemns. Califrnia Exp. Sta. Bui Westbrk, Jr., G. F. Effect f the use f freezedamaged fruit n the characteristics f frzen cncentrated range juices. "A dissertatin in partial fulfillment f the requirement fr Ph.D." Univ. f Flrida, June Yung, H. D The cmpsitin f frzen ranges and lemns. Ind. Eng. Chem. 7: EFFECT OF FIELD AND PACKINGHOUSE HANDLING ON BRUISING OF FLORIDA TOMATOES T. T. Hattn, Jr., Senir Hrticulturist W. F. Reeder, Bilgical Aid Market Quality Research Divisin Agricultural Marketing Service U. S. Department f Agriculture Miami Summary Mature-green tmates f the Hmestead va riety were evaluated fr external and internal bruising after each step frm harvest t packed fruit in fur separate shipping peratins in Dade Cunty, Flrida. Mst f the external bruising was incurred during harvesting, hauling, and dumping nt the grader. Hwever, mst f thse externally dam aged tmates were remved during cmmercial srting. Internal bruising tended t increase during the entire harvesting and packing prcess, al thugh a slight drp ccurred as a result f the remval f externally damaged tmates during grading. Objectinable internal bruising f the packed tmates varied frm 2.9 per cent in ne plant t 0.6 per cent in anther. This limited study indicates that the high in cidence f internal bruising ften fund in the market may result frm injuries incurred during transprt, and during handling at whlesale and retail rather than during harvesting and packing. Intrductin Internal bruising is ne f the principal de fects f fresh tmates. Cmmercial packers grade fruit fr disease and external damage, but internal bruising des nt becme evident until the fruit is ripened and cut.1 The purpse f this study was t determine the extent f external and internal bruising in jury f tmates, frm the time f harvest at mature-green stage, thrugh the packing pera tin, and t relate the bruising t cmmercial handling practices. Tmates bruised in the green stage are ften damaged befre certain f the placental tissues becme gelatinus and may result in'fail ure f the fruit t ripen nrmally. When ripe, such tmates may have dry lcules r dark, stringy, gelatinus tissues in the seed cavity. The bruising f tmates is cumulative frm increased handling as the fruit is harvested, transprted, ripened, and repacked.1 Studies f handling f tmates, harvested when turning and pink, have shwn that fruit in such an ad vanced stage f ripening were mre subject t bruising damage than were less ripe tmates.2 lmccolloch, LACY P Bruising Injury f T mates. U.S.D.A. Marketing Research Reprt N HALSEY, L. H Preliminary Studies f "Turning" and "Pink" Tmates Caused by Handling: Practices. Prc. Fla. State Hrt. Sc. 68: