TurkJAgricFor 28(2004)267-271 ©TÜB‹TAK MainOrganicAcidDistributionofAuthenticCitrusJuicesinTurkey FeryalKARADEN‹Z* AnkaraUniversity,FacultyofEngineering,DepartmentofFoodEngineering,CampusofAgriculturalFaculty, D›flkap›06110,Ankara–TURKEY Received:01.10.2003 Abstract: Nineteenauthenticcitrusjuicesamples(6tangerine,4sweetorange,4grapefruit,4lemonand1sourorange)were investigatedwithrespecttoorganicaciddistribution.Averagecitric,malicandfumaricacidcontentsoftangerinejuiceswer e9.22 gl-1,5.29gl-1 and368µgl-1,respectively.Thesevaluesfororangejuiceswere13.28gl-1,7.79gl-1 and373µgl-1,respectively. Thecitricacidconcentrationinlemonjuices,havingthehighestacidity,variedbetween48.54and60.32gl -1.Itwasfollowedby grapefruitjuiceswithanaverage19.61gl -1 citricacidcontent.Inallcitrusjuices,themostabundantorganicacidwascitricacid, rangingfrom6.05to60.32gl-1,withtheexceptionofonetangerinevariety.Malicacidwasthesecondmostabundantacid(1.27- 12.15gl-1),followedbyfumaricacid(0-807µgl -1).Grapefruit,lemonandsourorangejuicesdidnotcontainfumaricacid. KeyWords: organicacid,orange,grapefruit,lemon,tangerine Türkiye’dekiDo¤alTurunçgilSular›ndaBafll›caOrganikAsitlerinDa¤›l›m› Özet: 19adetdo¤alturunçgilmeyvesuyuörne¤inde(6mandarin,4portakal,4greyfrut,4limonve1turunç)organikasitda¤›l›m› araflt›r›lm›flt›r.Mandarinsular›ndakisitrik,malikvefumarikasitmiktarlar›ortalamaolaraks›ras›yla9.22gl-1,5.29gl-1 ve368µg l-1 olarakbelirlenmifltir.Portakalsular›ndaisebuasitlereaitde¤erlers›ras›yla13.28gl -1,7.79gl -1 ve373µgl -1 olarak saptanm›flt›r.Asitli¤ienyüksekolanlimonsular›ndasitrikasitmiktar›48.54-60.32gl -1 aras›ndade¤iflimgöstermektedir.Bunu ortalama19.61gl-1 sitrikasitmiktar›ilegreyfrutsuyuizlemektedir.Mandarinvaryetelerindenbirtanesihariç,turunçgilsular›ndaki baflatorganikasit6.05–60.32gl-1 aras›ndade¤iflensitrikasittir.Turunçgilsular›ndayayg›nolarakbulunanikinciasitmalikasittir (1.27-12.15gl-1)vebunufumarikasit(0-807µgl -1)izlemektedir.Greyfrut,limonveturunçsular›fumarikasitiçermemektedir. AnahtarSözcükler: organikasit,turunçgil,portakal,greyfrut,limon,mandarin Introduction combinationwithsugars,theyareimportantattributesof Organicacidsareausefulindexofauthenticityinfruit thesensoryqualityofrawandprocessedfruits(Wanget products,sincetheyhavelowersusceptibilitytochange al.,1993).Atthesametime,someorganicacidsmaybe duringprocessingandstoragethanothercomponentsof usedasindicatorsofripeness(PalmerandList,1973), fruits(Camaraetal.,1994).Accurateknowledgeof bacterialactivityandadulteration(Evansetal.,1983; organicacidlevels(andratios)mightbeusefulfor Blancoetal.,1996). determiningthepercentagejuicecontentofjuice Citrusfruitsareclassifiedasacidfruits,sincetheir products,andalsofordetectingmisbrandingand/or solublesolidsarecomposedmainlyoforganicacidsand adulterationinthisfoodclass(CoppolaandStarr,1986), sugars(KaleandAdsule,1995),whichareusedasthe sinceeachfruithasauniquepatternoforganicacids mainindexofmaturityandoneofthemajoranalytical (Wrolstad,1981).Theorganicacidcompositionoffruits measuresofflavorquality(Fellers,1991).Themainacids isalsoofinterestbecauseofitsimportantinfluenceon ofcitrusfruitsarecitricandmalicacids.Inaddition, thesensorypropertiesoffruitsandfruitjuices.Even tracesoftartaric,benzoic,oxalicandsuccinicacidshave thoughtheyareminorcomponentsoffruits,in alsobeenreported(KaleandAdsule,1995). *Correspondenceto:[email protected] 267 MainOrganicAcidDistributionofAuthenticCitrusJuicesinTurkey Thepresentstudywasundertakentodeterminethe iii.Organicacidstandards: Organicacids(citric, organicaciddistributionofcitrusjuicespreparedfrom fumaric,malic)wereobtainedfromAldrichCo.(Sigma- differentspeciesandvarietiesgrowninTurkey. AldrichChemie,Steinheim,Germany).Thestandard solutionswerepreparedindividuallyatdifferent concentrationswithdoubledistilledwater. MaterialsandMethods iv.HPLCconditions: Analyseswerecarriedoutona Materials BioRadAminexHPX-87ionexclusioncolumn(300x7.8 AllcitrusvarietiesweretakenfromtheMediterranean mm)precededbyaCation-HBioRadMicro-Guard region,whichisthemaincitrusgrowingareainTurkey. column(30x4.6mm)installedinaWatersliquid FruitsweresuppliedbytheCitrusFruitsandGreenhouse chromatographequippedwithaWaters510pumpanda ResearchCenterlocatedinAntalya.Allthesampleswere reodyneinjector.Columneffluentsweremonitoredbya storedat+5°Candprocessedintofruitjuicewithin1 UV-VISdetector(Waters486)setat214nm.Integration week. anddatastoragewereperformedbyMillennium2010 i.FruitJuiceProcessing: Fruitswerewashedintap Chromatographysoftware(MilliporeCo.,Milford,MA, waterandthencutinhalf.Fruitjuicewasextractedusing USA).Themobilephase(0.01NH 2SO4),usedataflow alabscalecitrusjuiceextractor(MoulinexT574,France). rateof0.6ml/min,wasfilteredthrougha0.45µ Afterjuiceextraction,rawjuicewasheatedat96°Cfor Milliporemembranefilter(HAWPMilliporeCo.)and 1mintoinactivateenzymes.Followingtheheating degassedinavacuum. process,thejuicesrapidlycooleddowntoroom v.Statisticalanalysis: Experimentswerereplicated temperature,werefilteredthrough8-foldedcheesecloth twiceandallanalyseswereperformedinduplicate.The toeliminateparticulatesandthenputinto200mlglass significanceofdifferencesamongdifferentspeciesand bottles.Afterbottling,alljuicesampleswerepasteurized differentvarietieswasdeterminedatthe95%levelof at96°Cfor20min.Then,thesampleswerecooledwith Tukey’sfamilyerrorrates,usingtheMinitabStatistical tapwaterandstoredat-18°Cuntilanalyzed. software(MinitabforWindows,version13,Minitab,Inc. 1998). Methods ThepHvalueofcitrusjuiceswasdeterminedwitha ResultsandDiscussion pHmeter(CONSORTP407,SCHOTTGERATE, Arepresentativechromatogramoforganicacidsin Belgium).Titratableacidity(TA)wasmeasuredbydirect citrusjuicesanalyzedbyHPLCisshowninFigure1.The titrationofa10mlsamplewith0.1NNaOHtopH8.1 peaksat8.42,10.08and16.57minrepresentcitric, andtheresultswereexpressedascitricacid.A malicandfumaricacids,respectively. refractometer(N.O.W.,NipponOpticalWorkCo.,Ltd., Tokyo,Japan)wasusedtodeterminethesolublesolids Theparametersofthemajororganicacids,titratable contentofjuices. acidity,pHandtotalsolublesolidsincitrusjuicesare giveninTable1.Asindicatedbyotherresearchers i.Organicacidanalysis: AslightlymodifiedHPLC (Clements,1964;Yamaki,1989),citricacidisthemain method(Evansetal.,1983)wasusedtodeterminethe organicacidfoundincitrusjuices(6.05-60.32gl -1), organicacidprofileofcitrusjuices.Thepeakswere exceptforClementinetangerine,whichcontains12.15g identifiedbyacomparisonoftheretentiontimeof l-1 malicacidand6.05gl -1 citricacid.Thesecondmost standardacidsandspikingthesamplewithstandard abundantacidwasmalicacid(1.27–12.15gl-1)inallthe compounds. citrusjuicesanalyzedexceptforClementine.Fumaric ii.Samplepreparation: Afterdilution,juicesamples acid,notdetectedingrapefruit,lemonorsourorange werecentrifugedat4000rpmfor2min.Supernatant juices,was81-807µgl -1 intheothercitrusjuices.Lee wasfilteredwithfilterpaperbeforebeingpassedthrough (1993)alsoreported0.4mg100ml -1 fumaricacidin a0.45µMilliporemembranefilter(HAWPMilliporeCo., orangejuice.Healsofoundtracesofoxalic,quinic, Bedford,MA,USA).Then20µlsampleswereinjected tartaric,isocitric,ascorbicandcis-aconiticacids.Ina intotheHPLC. studyof42citrusspecies,smalleramountsofacetate, 268 F.KARADEN‹Z 0.500 citric 8.417 0.400 malic 0.300 AU 0.200 10.083 fumaric 0.100 11.033 7.833 6.583 12.367 16.567 14.967 7.483 0.000 5.00 10.00 15.00 Minutes Figure1.AnHPLCchromatogramoforganicacidsinauthenticorangejuices. Table1.Organicacidcontentsofauthenticcitrusjuices. Species Variety Citric(gl-1) Malic(gl-1) Fumaric(µgl-1) TAcid(gl-1) pH TSS,% Tangerine(Citrusreticulata) Fremond 6.70±0.021 5.90±0.141 99±28.3 8.13±0.269 3.47±0.028 12.0±0.283 Authentic 12.04±0.156 4.32±0.056 626±7.07 12.10±0.092 3.44±0.017 10.7±0.354 Fairchild 9.22±0.028 5.44±0.077 442±8.49 10.24±0.085 3.51±0.021 13.1±0.317 Clementine 6.05±0.049 12.15±0.085 504±1.41 8.07±0.361 3.69±0.020 12.1±0.283 Minneola 12.14±0.205 1.27±0.091 251±7.07 13.95±0.184 3.17±0014 10.8±0.283 Satsuma 9.14±0.156 2.63±0.113 289±7.85 10.03±0.173 3.46±0.014 8.4±0.141 Minimum6.05 1.27 99 8.07 3.17 8.4 Maximum 12.14 12.15 626 13.95 3.69 13.1 Average 9.22 5.29 368 10.42 3.46 11.2 Sweetorange(Citrussinensis) Washington 11.10±0.021 9.13±0.127 87±5.66 11.14±0.092 3.48±0.014 11.5±0.283 Valencia 14.44±0.099 8.52±0.219 81±2.83 14.50±0.134 3.34±0.014 14.0±0.141 Shamouti 11.94±0.219 4.84±0.191 517±27.6 12.29±0.092 3.34±0.021 11.4±0.283 Authentic 15.65±0.057 8.67±0.134 807±62.2 15.57±0.085 3.22±0.021 11.5±0.283 Minimum11.10 4.84 81 11.14 3.22 11.4 Maximum 15.65 9.13 807 15.57 3.48 14.0 Average 13.28 7.79 373 13.38 3.34 12.1 Grapefruit(Citrusparadisi) Henderson 19.36±0.184 4.80±0.042 n.d. 21.39±0.078 3.00±0.007 10.1±0.424 MarshSeedless 24.25±0.474 3.48±0.170 n.d. 25.12±0.453 3.04±0.007 11.0±0.283 RedBlush 17.87±0.361 3.44±0.106 n.d. 18.88±0.156 2.99±0.014 9.5±0.424 StarRuby 16.96±0.106 4.40±0.021 n.d. 17.23±0.078 2.99±0.007 10.5±0.287 Minimum16.96 3.44 - 17.23 2.99 9.5 Maximum 24.25 4.80 - 25.12 3.04 11.0 Average 19.61 4.03 - 20.65 3.00 10.3 Lemon(Citruslimon) Kütdiken 60.32±0.311 4.97±0.042 n.d. 63.68±0.453 2.41±0.007 7.4±0.212 Karalimon 48.54±0.042 7.13±0.028 n.d. 52.80±0.453 2.46±0.007 8.5±0.283 Interdonato 51.87±0.431 5.07±0.049 n.d. 57.20±0.792 2.42±0.014 6.6±0.141 Lamas 59.72±1.216 6.82±0.099 n.d. 62.08±0.453 2.44±0.014 9.6±0.354 Minimum48.54 4.97 - 52.8 2.41 6.6 Maximum 60.32 7.13 - 63.68 2.46 9.6 Average 55.11 6.00 - 58.94 2.43 8.0 Sourorange(Citrusaurantium) 48.79±0.431 2.21±0.156 n.d. 48.48±0.679 2.60±0.021 10.0±0.283 T.Acid:titratableacidity,TSS:totalsolublesolids,n.d.:notdetected 269 MainOrganicAcidDistributionofAuthenticCitrusJuicesinTurkey pyruvate,oxalate,glutarate,fumarate,formate,succinate