Drying Technologies in Food Processing

350 Pages·2008·4.43 MB·English

by  Xiao Dong Chen

Drying Technologies in Food Processing
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Drying Technologies in Food Processing
Edited by
Xiao Dong Chen
Department of Chemical Engineering
Monash University
Melbourne, Victoria
Australia
Arun S. Mujumdar
Department of Mechanical Engineering
Faculty of Engineering
National University of Singapore
Singapore
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Thiseditionfirstpublished2008
©2008BlackwellPublishingLtd
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LibraryofCongressCataloging-in-PublicationData
Dryingtechnologiesinfoodprocessing/editedbyXiaoDongChen,ArunS.Mujumdar
p.cm.
Includesbibliographicalreferencesandindex.
ISBN-13:978-1-4051-5763-6(hardback:alk.paper)
ISBN-10:1-4051-5763-1(hardback:alk.paper)1.Drying.2.Foodindustryandtrade.
I.Chen,XiaoDong.II.Mujumdar,ArunS.
TP363.D79452008
(cid:1)
664.0284—dc22
2008006131
AcataloguerecordforthisbookisavailablefromtheBritishLibrary.
Setin10/12ptTimesbyNewgenImagingSystems(P)Ltd,Chennai,India
PrintedinSingaporebyC.O.S.PrintersPteLtd
1 2008
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Contents
Contributors xi
Preface xiii
Introduction:structuralimagesofsomefreshandprocessedfoods xv
XiaoDongChen
1 Fooddryingfundamentals 1
XiaoDongChen
1.1 Introductiontofoodmaterials 1
1.2 Dryingoffood 2
1.3 Physicalpropertiesoffoods 8
1.3.1 Thescalesofinterest 8
1.3.2 Mechanicalproperties 10
1.3.3 Shrinkageanddensities 15
1.3.4 Thermalpropertiesandconventionalheating 20
1.3.5 Colour 26
1.3.6 Equilibriumisotherms 29
1.4 Dryingratecharacteristiccurveapproachtocorrelatedryingrates–
vanMeel’smethod 30
1.5 Diffusiontheoriesofdrying 32
1.5.1 EffectiveFickiandiffusivity 32
1.5.2 Intuitiveunderstandingofthediffusiontheory 34
1.5.3 DryingoffoodssimulatedusingtheeffectiveFickian
diffusionlaw 36
1.5.4 Alternativeeffectivediffusiontheories 38
1.6 Driers 42
1.7 Concludingremarks 43
1.8 Notation 44
AppendixI:Typicalmasstransfercorrelations 46
AppendixII:Onthe‘effectiveness’oftheeffectivemoisturediffusivity
benchmarkedagainsttheLuikovtheory 46
AppendixIII:DryingofpulpedKiwifruitlayerformakingfruitleather 52
References 52
2 Wateractivityinfoodprocessingandpreservation 55
BheshR.BhandariandBenuP.Adhikari
2.1 Introduction 55
2.1.1 Thermodynamicsofwateractivity 56
2.1.2 Definitionandsignificance 57
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vi Contents
2.1.3 Sorptionisotherms 58
2.1.4 Hysteresisinsorptionisotherms 58
2.2 Composition-basedwateractivitypredictivemodels 59
2.2.1 Raoult’sLaw 59
2.2.2 Norrishmodel 60
2.2.3 Rossmodel 61
2.2.4 Money–Bornequation 62
2.2.5 Grovermodel 63
2.2.6 Salwinequation 64
2.3 Modelsforpredictionofsorptionisotherms 65
2.3.1 Two-parametermodels 65
2.3.2 Three-parameterisotherms 68
2.3.3 Effectoftemperatureonwateractivity 73
2.3.4 Wateractivityaboveboilingpoint 75
2.4 Typesofsorptionisothermsandhysteresisinisotherms 75
2.5 Determinationofsorptionisotherms 78
2.5.1 Gravimetricmethod 78
2.5.2 Manometricmethod 83
2.5.3 Hygroscopicmethods 84
2.5.4 Samplepreparationandequilibriumtime 84
2.6 Concludingremarks 86
References 86
3 Biologicalchangesduringfooddryingprocesses 90
XiaoDongChenandKamleshC.Patel
3.1 Introductiontodryingandfoodquality 90
3.2 Post-dryingproblems 91
3.3 In-dryingproblems 95
3.4 Foodbio-deteriorationbydrying–asub-celllevelapproach 106
3.5 Concludingremarks 108
3.6 Notation 109
References 109
4 Spraydryingoffoodmaterials–processandproductcharacteristics 113
BheshR.Bhandari,KamleshC.PatelandXiaoDongChen
4.1 Introduction 113
4.2 Basicconceptsofspraydrying 114
4.3 Componentsofaspraydryingsystem 117
4.3.1 Dryinggassupplyandheatingsystem 117
4.3.2 Atomizationsystem 118
4.3.3 Dryingchamber 121
4.3.4 Powderseparators 122
4.4 Dryingofdroplets 125
4.4.1 Fundamentalsofdropletdrying 125
4.4.2 Dryingkinetics 126
4.4.3 Residencetime 129
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Contents vii
4.5 Massandheatbalancesoveraspraydrier 130
4.5.1 Overallmassbalance 130
4.5.2 Overallheatbalance 133
4.6 Drierefficiency 134
4.6.1 Thermalefficiency 134
4.6.2 Evaporativeefficiency 136
4.6.3 Volumetricevaporativecapacity 136
4.7 Powdercharacterization 137
4.7.1 Particlemicro-structure 137
4.7.2 Particlemorphology 139
4.7.3 Physicalandfunctionalpropertiesofpowder 141
4.7.4 Dryingparameters 147
4.8 Spraydryingofvariousfoodproducts 149
4.8.1 Dairypowders 149
4.8.2 Micro-encapsulatedpowders 151
4.8.3 Sugar-richproducts 153
4.8.4 Egg 154
4.8.5 Enzymes 154
4.9 Concludingremarks 155
4.10 Notation 155
References 157
5 Low-pressuresuperheatedsteamdryingoffoodproducts 160
SakamonDevahastinandPeamsukSuvarnakuta
5.1 Introduction 160
5.2 Basicprinciplesofsuperheatedsteamdrying 161
5.3 Low-pressuresuperheatedsteamdryingoffoodsandbiomaterials 163
5.4 SomeadvancesinLPSSDoffoodsandbiomaterials 177
5.5 MathematicalmodelingofLPSSDoffoodsandbiomaterials 182
5.6 Concludingremarks 186
5.7 Notation 187
References 187
6 Heatpump-assisteddrying 190
MdRaisulIslamandArunS.Mujumdar
6.1 Introduction 190
6.2 Classificationofheatpumpdriers 191
6.3 Fundamentalsofheatpumpdriers 191
6.4 Heatandmasstransfermechanisms 197
6.5 Optimumuseofheatpumpsindryingsystems 210
6.6 Innovativeheatpumpdryingsystems 212
6.6.1 Multi-stagecompressionheatpumpdrying 213
6.6.2 Cascadeheatpumpdryingsystems 214
6.6.3 Heatpumpdryingsystemswithmultipleevaporatorsin
seriesandinparallel 215
6.6.4 Vaporabsorptionheatpumpdrier 217
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viii Contents
6.7 Closingremarks 221
6.8 Notation 222
References 223
7 Freezeandvacuumdryingoffoods 225
CristinaRatti
7.1 Introduction 225
7.2 Statesofwater 225
7.3 Foodandairpropertiesinrelationtovacuumandfreeze-drying 227
7.4 Heattransfermechanismsatlowpressures 232
7.5 Vacuumdrying:principlesanddehydrationmodels 234
7.6 Freezedrying:principlesanddehydrationmodels 236
7.7 Illustrativeexample 239
7.8 Advancesinvacuumandfreezedryingoffoods 243
7.9 Closure 245
7.10 Notation 245
References 246
8 Post-dryingaspectsformeatandhorticulturalproducts 252
MohammadShafiurRahman
8.1 Introduction 252
8.2 Statediagramandstabilityconceptsofdriedproducts 252
8.3 Controllingqualityattributes 255
8.3.1 Microbialquality 255
8.3.2 Chemicalchangesandquality 257
8.3.3 Physicalchangesandquality 260
8.3.4 Vitaminsretention 265
8.4 Conclusion 265
References 265
9 Fooddrierprocesscontrol 270
BrentR.Young
9.1 Introduction–whyprocesscontrol? 270
9.1.1 Disturbancevariables 270
9.1.2 Controlbenefits 271
9.1.3 Examples 271
9.1.4 Chapterorganization 272
9.2 Whattocontrol(manipulatedandcontrolledvariables) 272
9.2.1 Controlledvariables 272
9.2.2 Manipulatedvariables 273
9.3 Wheretocontrol(controlstrategy) 273
9.3.1 Plant-widecontrolstrategyconfiguration 273
9.3.2 Commonloopsandexamples 274
9.4 Whentocontrol(controlphilosophy) 276
9.4.1 Aftersomethinghappens–feedbackcontrol 276
9.4.2 Assomethinghappens–feed-forward/predictivecontrol 278
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Contents ix
9.5 Howtocontrol(fundamentalcontrolmethods) 279
9.5.1 PIDfeedbackcontrolandtuning 279
9.6 Howtodoadvancedcontrol(advancedcontrolmethods) 292
9.6.1 Modelpredictivecontrol(MPC) 293
9.6.2 Adaptivecontrol 295
9.6.3 Artificialintelligenceincontrol 295
References 297
10 Fireandexplosionprotectioninfooddriers 299
XiaoDongChen
10.1 Introduction–thermalhazardsindriers 299
10.1.1 Conditionsforanexplosiontooccur 299
10.1.2 Howseriousistheproblem? 300
10.1.3 Whataffectsthedegreeofviolenceofadustexplosion? 300
10.1.4 Howtoreducetheriskofdustexplosion 301
10.2 Apracticalexample:milkpowderplantsafety 301
10.2.1 Fires 302
10.2.2 Explosionprotection 310
10.3 Testingforvariousexplosionparameters 314
10.4 Thehumanfactors 314
10.5 Concludingremarks 316
References 316
Index 319
Thecolourplatesectionfollowspage40
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