Aroma and taste impact components in grapefruit juice

163 Pages·1998·3.6 MB·English

by  Jella, Prashanthi

AROMAANDTASTEIMPACTCOMPONENTSIN
GRAPEFRUITJUICE
By
PRASHANTHIJELLA
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1998
ThisthesisisdedicatedtoShirdiSai.
ACKNOWLEDGMENTS
IIiwouldliketoexpressmygratitudetomyadvisorDr.RussellRouseffforhis
assistanceandsupportduringthecourseofmyresearch.Hisconstantencouragement
promotedindependentthoughtandhiswords"YouCanDoIt","GoGetThem"
challengedmeateveryturnandrefusedtoletmesettleforsuperficialsolutionsforcritical
problems.Heisagoodteacher,anexceptionalpersonandIamgladthatIgotachance
toworkwithhim.
IwouldalsoliketothankmycommitteemembersDr.Gregory,Dr.0'K.eefe,Dr.
Powell,Dr.SimsandDr.Teixeirafortheirguidanceinthisproject.Dr.Gregoryisoneof
theteachersIadmireforpromotingcriticalthinkinginhisstudents.Hisquestionsduring
seminarswerealways"topicstoruminate"formyfriendsandme.
IhadanopportunitytositthroughsomeofDr.Teixeira'sclassesandtheywere
oneofthemostcherishedexperiencesforme.Iwillneverforgetthedefinitionof"a
thixotropicfluid"andthewayhedemonstrateditintheclass.Heisoneofthebest
teachersIhad,whonevertooknoforananswerbuthelpedthestudentstoworkthrough
theproblem.
TherearenowordstoexpressmythankstofriendsandroommatesfromTexas
A&M,whoarelikeasecondfamilytome.ThebondingwehaveisaspecialoneandI
willalwayscherishit.TheyaretheoneofthereasonsformakingmystayinUSworth
while.
ThankstomyfriendsatUFwhomadegoingtoschoolanenjoyableexperience.I
missthetimeIsharedwithMitwe,Pimpen,Cynthia,Alex,RenaandJamie.Theyarethe
peoplewhomIadmirefortheirqualities,and1amgladthatIamfriendswiththem.
IappreciatethelearningexperiencesandhelpfromRusty,KevinandHaroldinour
lab.WordsfailtoexpressthegratitudeforpanelmembersatUSDAandespeciallyUli.
UliisthepersonIadmireforhisliberaloutlookandbroadknowledgeaboutothercultures
oftheworld.
Mydeepestandmostsinceregratitudeistomyfamily.Myparentswerea
constantsupportandtheirguidanceandencouragementisayardstickformy
advancement.Theimportancetheyplacedongoodeducationandtheirphilosophyof
"alwaysstriveforbetterbutbehappywithwhatyouhave"mademysister,brotherand
methekindofpersonswearetoday.Ioweittothem.Myfather'sdynamismandmy
mother'sliberalthinkingaresourceofinspirationtometotryanything.
Ifthereisonepersonwhowasmoreproudofmeandmyachievements,itwasmy
grandfather.Hewasagreatteacher,exceptionalhumanbeingandphilanthropistwho
touchedmanylivesotherthanhisfamily.Hismemoriesarepermanentlyetchedinmy
heart.MypaternalandmaternalgrandmothersarethewomenIadmiremost.Their
strengthandintelligenceareasourceofinspirationinmylife.Specialthankstomy
uncles,auntsandcousinsfortheiremotionalsupport.
IV
Myfather-andmother-in-lawareagreatsupporttome.Theytreatmeliketheir
owndaughterandstandbymeinallsituations.Theyinvitedmeintotheirfamilyagainst
alltraditionalIndiannorms.Iameverthankfultothemforit.
OfallthefriendsIhave,thebestofthemismylifepartnerRohini.Hislove,
support,patience,encouragementaresourcesformystrength.Heisthehappinessinmy
life.Withouthimthiswouldnotbepossible.AllIcansaytohimisTHANKYOU
ROHINI!!!
TABLEOFCONTENTS
ACKNOWLEDGMENTS
jjj
LISTOFTABLES ix
LISTOFFIGURES xi
ABSTRACT xjv
CHAPTERS
1.INTRODUCTION 1
2 LITERATUREREVIEW 4
Flavor 4
StatisticalCorrelations 5
Bitterness 7
GC-Olfactometry 9
ACOhESaDMrAEm®Analysis 11009
SampleSPrPeMpaEration 1132
SulfurCompounds 15
3.MATERIALSANDMETHODS 17
GrapefruitJuiceSampleCollection 17
SurveySamples 17
Methylenechlorideextracts 17
Pentane-diethyletherextracts 18
GC-OlfactometrySamples 18
SamplePreparation 19
Liquid-LiquidExtractionwithMethyleneChloride 19
Liquid-LiquidExtractionwithPentane-Diethylether(1:1): 20
DynamicHeadSpacePurgeandTrapSolventElution 20
ExtractionProcedureforSulfurCompounds 21
ExtractionProcedureforGC-OlfactometryAnalysis 21
InstrumentalTechniques 21
GC-FlameIonizationDetector 21
GC-SulfurChemiluminescenceDetector 22
GC-MassSpectrometry 24
LimoninandNaringinAnalysisUsingHPLC 24
Samplepreparation 24
HPLCinstrumentation 25
PeakIdentificationandQuantification 25
SensoryDUASOnaDClAyPsriDesefsecrreinpcteivPeanPealnel 223177
TrainingofPanelists 33
GC-OlfactometryPanel 33
DescriptivePanel 34
StatisticalAnalysis 34
4 RESULTSANDDISCUSSION 36
CorrelationsBetweenPreferenceandAnalyticalMeasurements 36
SensoryAnalysis 40
StatisticalAnalysis 40
Univariateanalysis 40
Multivariateanalysis 43
IdentificationofthePeakatRI-1126 54
GrapefruitJuiceAromaExtractionMethods 56
ChromatographicSeparationandAnalysis 56
ExtractionMethods 58
Liquid-liquidextractions 58
Dynamicheadspaceextraction 62
StaticheadspaceextractionusingSPME 64
GC-OlfactometryStudies 65
InstrumentalDetectorsvs.HumanResponse 65
MaturityandProcessingChanges 69
StandardDescriptorsVs.Panelist'sDescriptors 76
GrapefruitAroma 80
SulfurCDoimluptoiuonndAsnalinysGirsapefruit 8812
Detection 82
ProcessingandMaturityEffects 84
p-menthene-8-thiol 88
CorrelationBetweenAromaComponentsandSensoryMeasurements 89
vn
JuiceClassification 89
SensoryAnalysis 90
UnivariateAnalysis 93
Tastecomponents 93
Aromacomponents 100
MultivariateStatisticalAnalysis 104
Flavormodelsusingtastecomponents 105
FFllaavvoorrmmooddeellssuussiinnggaarroommaaacnodmptoansteenctosmponents 1I0ll7
5.CONCLUSIONS 119
CorrelationBetweenPreferenceandAnalyticalMeasurements 119
AromaExtractionMethods 120
GC-Olfactometry 121
SulfurCompoundsinGrapefruitJuice 122
CorrelationsBetweenAromaComponentsandSensoryMeasurements 123
APPENDICES
A.TOTALIONCHROMATOGRAMOFLATESEASONGRAPEFRUITJUICE 125
B.MASSSPECTRUMOFVANILLIN 127
C LISTOFDESCRIPTORSANDTHEIRRELATIVEINTENSITIES(GC-O).. 129
D COMPOUNDSIDENTIFIEDINNOT-FROM-CONCENTRATEGRAPEFRUIT
JUICE I32
LISTOFREFERENCES 136
BIOGRAPHICALSKETCH 144
.
LISTOFTABLES
Table page
1 Calibrationequationsusedforcalculatingtheconcentrationsofcomponents
detectedinGC-FID * 29
2. Maximum,minimumandaverageareapercentforcomponentsextractedwith
methylenechloride 3g
3. Univariatecorrelationsofselectedvolatileandnon-volatiledatawithpreference
category 41
4. Forwardstepwisediscriminantanalysis(methylenechlorideextractions) 50
5. Discriminantanalysisclassificationresults(methylenechlorideextracts) 51
6. Percentrelativestandarddeviationfordifferentaromaextractionmethodsin
grapefruitjuice 60
7. Topnotepeakareasfordifferentaromaextractionmethods 61
8. Formationandlossofaromaattributesduetopasteurizationinearlyseasonred
grapefruitjuices 72
9. Concentrationlevels(ppm)ofcomponentsinearly,midandlateseasonred
grapefruitjuices 75
10. AromadescriptorsusedbypanelistsfromGC-0experimentsofcitrusstandards78
11. Comparisonofstandard(Arctanderlexicon)withpanelistdescriptors 79
12. Lainsdtaorfocmoampaottnreinbuttsespresentin16xconcentratedjuiceextractandtheirintensities83
13. Minimumandmaximumdescriptivesensorypanelscoresforgrapefruitjuices..92
14. Univariatecorrelationsbetweensensoryandtastecomponents(Brix,acid,ratio,
limoninandnaringin) 94
15 Univariatecorrelationsbetween26aromaactivevolatilesandsensoryscores. 1 1
16. Squaredmahalanobisdistancesforgroupsseparatedbytastecomponents(Brix,
acid,ratio,limonin,andnaringin) 108
17. Squaredmahalanobisdistancesfor26aromaand5tastecomponents(Standard
DiscriminantAnalysis) 112
18. Forwardstepwisediscriminantanalysis-volatilesandtastecomponents(Number
ofstepsandcorrespondingcomponent) 116
19. Comparisonofsensoryandstatisticalclassificationofgrapefruitjuices.(Model
hasbeentestedusing17aromacomponentsand5tastecomponents) 117