Table Of ContentFood Chemistry
H.-D. Belitz · W. Grosch · P. Schieberle
Food Chemistry
4th revised and extended ed.
With481Figures,923Formulasand634Tables
123
ProfessorDr.Hans-DieterBelitz†
Professorem.Dr.WernerGrosch
Ehem.apl.ProfessorfürLebensmittelchemie
anderTechnischenUniversitätMünchen
Ehem.stellvertr.DirektorderDeutschenForschungsanstalt
fürLebensmittelchemieMünchen
Lichtenbergstraße
85748Garching
ProfessorDr.PeterSchieberle
OrdinariusfürLebensmittelchemie
anderTechnischenUniversitätMünchen
LeiterdesInstitutsfürLebensmittelchemie
anderTechnischenUniversitätMünchen
DirektorderDeutschenForschungsanstalt
fürLebensmittelchemieMünchen
Lichtenbergstraße
85748Garching
ISBN 978-3-540-69933-0 e-ISBN 978-3-540-69934-7
DOI10.1007/978-3-540-69934-7
LibraryofCongressControlNumber:2008931197
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Preface
Preface to the FirstGermanEdition
The very rapid development of food chemistry and technology over the last two
decades,whichisduetoaremarkableincreaseintheanalyticalandmanufacturing
possibilities, makes the complete lack of a comprehensive, teaching or reference
text particularly noticeable. It is hoped that this textbook of food chemistry will
helptofillthisgap.Inwritingthisvolumewewereabletodrawonourexperience
from the lectures which wehave given, covering various scientificsubjects, over
thepastfifteenyearsattheTechnicalUniversityofMunich.
Sinceaseparatetreatmentoftheimportantfoodconstituents(proteins,lipids,car-
bohydrates,flavorcompounds,etc.)andoftheimportantfoodgroups(milk,meat,
eggs,cereals,fruits,vegetables,etc.)hasprovedsuccessfulinourlectures,thesub-
jectmatterisalsoorganizedinthesamewayinthisbook.
Compounds which are found only in particular foods are discussed where they
play a distinctive role while food additives and contaminants are treated in their
ownchapters.Thephysical andchemical properties oftheimportant constituents
of foods are discussed in detail where these form the basis for understanding ei-
therthereactionswhichoccur,orcanbeexpectedtooccur,duringtheproduction,
processing,storageandhandlingoffoodsorthemethodsusedinanalyzingthem.
Anattempthasalsobeenmadetoclarifytherelationshipbetweenthestructureand
propertiesatthelevelofindividualfoodconstituentsandatthelevelofthewhole
foodsystem.
The book focuses on the chemistry of foodstuffs and does not consider national
or international food regulations. We have also omitted a broader discussion of
aspectsrelatedtothenutritionalvalue,theprocessingandthetoxicologyoffoods.
Alloftheseareanessentialpartofthetrainingofafoodchemistbut,becauseofthe
extent of thesubject matterand theconsequent specialization, must today bethe
subjectofseparatebooks.Nevertheless,forallimportant foodswehaveincluded
briefdiscussionsofmanufacturing processesandtheirparameterssincetheseare
closelyrelatedtothechemicalreactionsoccurringinfoods.
Commodityandproductiondataofimportancetofoodchemistsaremainlygiven
in tabular form. Each chapter includes some references which are not intended
toformanexhaustivelist.Nopreferenceorjudgementshouldbeinferredfromthe
choiceofreferences;theyaregivensimplytoencouragefurtherreading.Additional
literatureofamoregeneralnatureisgivenattheendofthebook.
This book is primarily aimed both at students of food and general chemistry but
alsoatthosestudentsofotherdisciplineswhoarerequiredorchoosetostudyfood
chemistry asasupplementary subject. Wealsohope that thiscomprehensive text
vi Preface
will prove useful to both food chemists and chemists who have completed their
formaleducation.
WethanksincerelyMrs.A.Mödl(foodchemist),Mrs.R.Berger,Mrs.I.Hofmeier,
Mrs.E.Hortig,Mrs.F.LynenandMrs.K.Wüstfortheirhelpduringtheprepara-
tionofthemanuscriptanditsproofreading.WeareverygratefultoSpringerVerlag
fortheirconsiderationofourwishesandfortheagreeablecooperation.
Garching, H.-D.Belitz
July1982 W.Grosch
Preface to the FourthEnglishEdition
The fourth edition of the “Food Chemistry” textbook is a translation of the sixth
German edition of this textbook. It follows a general concept as detailed in the
preface tothefirsteditiongiven below. Allchapters have beencarefully checked
and updated with respect to the latest developments, if required. Comprehensive
changeshavebeenmadeinChapters9(Contaminants),18(PhenolicCompounds),
20 (Alcoholic Beverages)and 21(Tea, Cocoa). Thefollowing topics werenewly
added:
(cid:129) thedetectionofBSEandD-aminoacids,
(cid:129) theformationandoccurrenceofacrylamideandfuran,
(cid:129) compoundshavingacoolingeffect,
(cid:129) technologicallyimportantmilkenzymes,
(cid:129) thelipoproteinsofeggyolk,
(cid:129) thestructureofthemuscleandmeataging,
(cid:129) foodallergies,
(cid:129) thebakingprocess,
(cid:129) thereactivityofoxygenspeciesinfoods,
(cid:129) phytosterols,
(cid:129) glycemicindex,
(cid:129) thecompositionofaromaswasextended:odorants(pineapple,rawandcooked
mutton, black tea, cocoa powder, whisky) and taste compounds (black tea,
roastedcocoa,coffeedrink).
Theproduction datafortheyear2006weretakenfromtheFAOviaInternet.The
volumeofthebookwasnotchangedduringtherevisionassomeexistingchapters
wereshortened.
Weareverygrateful toDr.MargaretBurghagen fortranslatingthemanuscript.It
wasourpleasuretocollaboratewithher.
WewouldalsoliketothankProf.Dr.JürgenWederandDr.RolfKiefferforseveral
valuablerecommendations.WearealsogratefultoSabineBijewitzandRitaJauker
forassistanceincompletingthemanuscript,andChristelHoffmannforhelpwith
theliteratureandtheindex.
Garching, W.Grosch
Mai2008 P.Schieberle
Contents
0 Water................................................. 1
0.1 Foreword .............................................. 1
0.2 Structure............................................... 1
0.2.1 WaterMolecule......................................... 1
0.2.2 LiquidWaterandIce .................................... 2
0.3 EffectonStorageLife.................................... 3
0.3.1 WaterActivity .......................................... 3
0.3.2 WaterActivityasanIndicator ............................. 5
0.3.3 PhaseTransitionofFoodsContainingWater................. 5
0.3.4 WLFEquation.......................................... 6
0.3.5 Conclusion............................................. 7
0.4 References ............................................. 7
1 AminoAcids,Peptides,Proteins ......................... 8
1.1 Foreword .............................................. 8
1.2 AminoAcids ........................................... 8
1.2.1 GeneralRemarks........................................ 8
1.2.2 Classification,DiscoveryandOccurrence ................... 9
1.2.2.1 Classification........................................... 9
1.2.2.2 DiscoveryandOccurrence................................ 9
1.2.3 PhysicalProperties ...................................... 12
1.2.3.1 Dissociation............................................ 12
1.2.3.2 ConfigurationandOpticalActivity......................... 13
1.2.3.3 Solubility .............................................. 14
1.2.3.4 UV-Absorption ......................................... 15
1.2.4 ChemicalReactions ..................................... 16
1.2.4.1 EsterificationofCarboxylGroups.......................... 16
1.2.4.2 ReactionsofAminoGroups............................... 16
1.2.4.2.1 Acylation .............................................. 16
1.2.4.2.2 AlkylationandArylation ................................. 18
1.2.4.2.3 CarbamoylandThiocarbamoylDerivatives.................. 20
1.2.4.2.4 ReactionswithCarbonylCompounds....................... 21
1.2.4.3 ReactionsInvolvingOtherFunctionalGroups................ 22
1.2.4.3.1 Lysine................................................. 23
1.2.4.3.2 Arginine............................................... 23
1.2.4.3.3 AsparticandGlutamicAcids.............................. 23
1.2.4.3.4 SerineandThreonine .................................... 24
1.2.4.3.5 CysteineandCystine .................................... 24
1.2.4.3.6 Methionine............................................. 24
1.2.4.3.7 Tyrosine ............................................... 24
viii Contents
1.2.4.4 ReactionsofAminoAcidsatHigherTemperatures ........... 25
1.2.4.4.1 Acrylamide ............................................ 25
1.2.4.4.2 MutagenicHeterocyclicCompounds ....................... 26
1.2.5 SyntheticAminoAcidsUtilizedforIncreasing
theBiologicalValueofFood(FoodFortification)............. 29
1.2.5.1 GlutamicAcid.......................................... 32
1.2.5.2 AsparticAcid........................................... 32
1.2.5.3 Lysine................................................. 32
1.2.5.4 Methionine............................................. 33
1.2.5.5 Phenylalanine .......................................... 33
1.2.5.6 Threonine.............................................. 33
1.2.5.7 Tryptophan............................................. 33
1.2.6 SensoryProperties ...................................... 34
1.3 Peptides ............................................... 34
1.3.1 GeneralRemarks,Nomenclature........................... 34
1.3.2 PhysicalProperties ...................................... 36
1.3.2.1 Dissociation............................................ 36
1.3.3 SensoryProperties ...................................... 36
1.3.4 IndividualPeptides ...................................... 38
1.3.4.1 Glutathione ............................................ 38
1.3.4.2 Carnosine,AnserineandBalenine ......................... 39
1.3.4.3 Nisin.................................................. 39
1.3.4.4 LysinePeptides ......................................... 40
1.3.4.5 OtherPeptides.......................................... 40
1.4 Proteins ............................................... 40
1.4.1 AminoAcidSequence ................................... 41
1.4.1.1 AminoAcidComposition,Subunits ........................ 41
1.4.1.2 TerminalGroups ........................................ 42
1.4.1.3 PartialHydrolysis ....................................... 43
1.4.1.4 SequenceAnalysis ...................................... 44
1.4.1.5 DerivationofAminoAcidSequence
fromtheNucleotideSequenceoftheCodingGene ........... 46
1.4.2 Conformation .......................................... 48
1.4.2.1 ExtendedPeptideChains ................................. 48
1.4.2.2 SecondaryStructure(RegularStructuralElements) ........... 49
1.4.2.2.1 β-Sheet................................................ 50
1.4.2.2.2 HelicalStructures ....................................... 51
1.4.2.2.3 ReverseTurns .......................................... 52
1.4.2.2.4 Super-SecondaryStructures............................... 52
1.4.2.3 TertiaryandQuaternaryStructures ......................... 53
1.4.2.3.1 FibrousProteins ........................................ 53
1.4.2.3.2 GlobularProteins ....................................... 53
1.4.2.3.3 BSE .................................................. 55
1.4.2.3.4 QuaternaryStructures.................................... 56
1.4.2.4 Denaturation ........................................... 56
1.4.3 PhysicalProperties ...................................... 58
1.4.3.1 Dissociation............................................ 58
1.4.3.2 OpticalActivity......................................... 60
1.4.3.3 Solubility,HydrationandSwellingPower ................... 60
1.4.3.4 FoamFormationandFoamStabilization .................... 62
1.4.3.5 GelFormation .......................................... 62
Contents ix
1.4.3.6 EmulsifyingEffect ...................................... 63
1.4.4 ChemicalReactions ..................................... 64
1.4.4.1 LysineResidue ......................................... 64
1.4.4.1.1 ReactionsWhichRetainthePositiveCharge................. 64
1.4.4.1.2 ReactionsResultinginaLossofPositiveCharge ............. 65
1.4.4.1.3 ReactionsResultinginaNegativeCharge ................... 65
1.4.4.1.4 ReversibleReactions..................................... 66
1.4.4.2 ArginineResidue........................................ 66
1.4.4.3 GlutamicandAsparticAcidResidues ...................... 67
1.4.4.4 CystineResidue(cf.alsoSection1.2.4.3.5).................. 67
1.4.4.5 CysteineResidue(cf.alsoSection1.2.4.3.5)................. 68
1.4.4.6 MethionineResidue ..................................... 69
1.4.4.7 HistidineResidue ....................................... 69
1.4.4.8 TryptophanResidue ..................................... 70
1.4.4.9 TyrosineResidue........................................ 70
1.4.4.10 BifunctionalReagents ................................... 70
1.4.4.11 ReactionsInvolvedinFoodProcessing ..................... 70
1.4.5 Enzyme-CatalyzedReactions ............................. 74
1.4.5.1 Foreword .............................................. 74
1.4.5.2 ProteolyticEnzymes..................................... 74
1.4.5.2.1 SerineEndopeptidases ................................... 74
1.4.5.2.2 CysteineEndopeptidases ................................. 76
1.4.5.2.3 MetaloPeptidases....................................... 76
1.4.5.2.4 AsparticEndopeptidases ................................. 76
1.4.6 ChemicalandEnzymaticReactions
ofInteresttoFoodProcessing ............................. 79
1.4.6.1 Foreword .............................................. 79
1.4.6.2 ChemicalModification................................... 80
1.4.6.2.1 Acylation .............................................. 80
1.4.6.2.2 Alkylation ............................................. 82
1.4.6.2.3 RedoxReactionsInvolvingCysteineandCystine............. 82
1.4.6.3 EnzymaticModification.................................. 83
1.4.6.3.1 Dephosphorylation ...................................... 83
1.4.6.3.2 PlasteinReaction........................................ 83
1.4.6.3.3 Cross-Linking .......................................... 86
1.4.7 TexturizedProteins...................................... 87
1.4.7.1 Foreword .............................................. 87
1.4.7.2 StartingMaterial ........................................ 88
1.4.7.3 Texturization ........................................... 88
1.4.7.3.1 SpinProcess ........................................... 88
1.4.7.3.2 ExtrusionProcess ....................................... 89
1.5 References ............................................. 89
2 Enzymes .............................................. 93
2.1 Foreword .............................................. 93
2.2 GeneralRemarks,IsolationandNomenclature ............... 93
2.2.1 Catalysis............................................... 93
2.2.2 Specificity ............................................. 94
2.2.2.1 SubstrateSpecificity..................................... 94
2.2.2.2 ReactionSpecificity ..................................... 95
2.2.3 Structure............................................... 95
x Contents
2.2.4 IsolationandPurification ................................. 96
2.2.5 MultipleFormsofEnzymes............................... 97
2.2.6 Nomenclature .......................................... 97
2.2.7 ActivityUnits .......................................... 98
2.3 EnzymeCofactors....................................... 98
2.3.1 Cosubstrates............................................ 99
2.3.1.1 NicotinamideAdenineDinucleotide........................ 99
2.3.1.2 AdenosineTriphosphate.................................. 102
2.3.2 ProstheticGroups ....................................... 102
2.3.2.1 Flavins ................................................ 102
2.3.2.2 Hemin................................................. 103
2.3.2.3 PyridoxalPhosphate..................................... 103
2.3.3 MetalIons ............................................. 104
2.3.3.1 Magnesium,CalciumandZinc ............................ 104
2.3.3.2 Iron,CopperandMolybdenum ............................ 105
2.4 TheoryofEnzymeCatalysis .............................. 106
2.4.1 ActiveSite ............................................. 106
2.4.1.1 ActiveSiteLocalization.................................. 107
2.4.1.2 SubstrateBinding ....................................... 108
2.4.1.2.1 Stereospecificity ........................................ 108
2.4.1.2.2 “LockandKey”Hypothesis............................... 109
2.4.1.2.3 Induced-fitModel ....................................... 109
2.4.2 ReasonsforCatalyticActivity............................. 110
2.4.2.1 StericEffects–OrientationEffects......................... 111
2.4.2.2 StructuralComplementaritytoTransitionState............... 112
2.4.2.3 EntropyEffect .......................................... 112
2.4.2.4 GeneralAcid–BaseCatalysis.............................. 113
2.4.2.5 CovalentCatalysis ...................................... 114
2.4.3 ClosingRemarks........................................ 117
2.5 KineticsofEnzyme-CatalyzedReactions ................... 117
2.5.1 EffectofSubstrateConcentration .......................... 117
2.5.1.1 Single-SubstrateReactions ............................... 117
2.5.1.1.1 Michaelis–MentenEquation .............................. 117
2.5.1.1.2 DeterminationofK andV............................... 120
m
2.5.1.2 Two-SubstrateReactions ................................. 121
2.5.1.2.1 OrderofSubstrateBinding ............................... 121
2.5.1.2.2 RateEquationsforaTwo-SubstrateReaction ................ 122
2.5.1.3 AllostericEnzymes...................................... 123
2.5.2 EffectofInhibitors ...................................... 125
2.5.2.1 IrreversibleInhibition.................................... 126
2.5.2.2 ReversibleInhibition .................................... 126
2.5.2.2.1 CompetitiveInhibition ................................... 126
2.5.2.2.2 Non-CompetitiveInhibition............................... 127
2.5.2.2.3 UncompetitiveInhibition ................................. 128
2.5.3 EffectofpHonEnzymeActivity .......................... 128
2.5.4 InfluenceofTemperature ................................. 130
2.5.4.1 TimeDependenceofEffects .............................. 131
2.5.4.2 TemperatureDependenceofEffects ........................ 131
2.5.4.3 TemperatureOptimum ................................... 133
2.5.4.4 ThermalStability ....................................... 134
2.5.5 InfluenceofPressure .................................... 136
