Drying Technologies in Food Processing

✍ Scribed by Xiao Dong Chen, Arun S. Mujumdar

• Publisher: Wiley-Blackwell
• Year: 2008
• Tongue: English
• Leaves: 350
• Edition: 1
• Category: Library

✦ Synopsis

Drying is of fundamental importance in most sectors of food processing. This volume provides an up to date account of all the major drying technologies employed in the food industry and their underlying scientific principles and effects. Various equipment designs are classified and described. The impact of drying on food properties is covered, and the micro-structural changes caused by the process are examined, highlighting their usefulness in process analysis and food design. Key methods for assessing food properties of dried products are described, and pre-concentration and drying control strategies are reviewed. Thermal hazards and fire/explosion detection and prevention for dryers are discussed. Where appropriate, sample calculations are included for engineers and technologists to follow.The book is directed at food scientists and technologists in industry and research, food engineers and drying equipment manufacturers.

✦ Table of Contents

Drying Technologies in Food Processing......Page 1
Contributors......Page 11
Preface......Page 13
Introduction: structural images of some
fresh and processed foods
Compiled by Xiao Dong Chen......Page 15
1.1 INTRODUCTION TO FOOD MATERIALS......Page 25
1.2 DRYING OF FOOD......Page 26
1.3.1 The scales of interest......Page 32
1.3.2 Mechanical properties......Page 34
1.3.3 Shrinkage and densities......Page 39
1.3.4 Thermal properties and conventional heating......Page 44
1.3.5 Colour......Page 50
1.3.6 Equilibrium isotherms......Page 53
1.4 DRYING RATE CHARACTERISTIC CURVE APPROACH TO
CORRELATE DRYING RATES – VAN MEEL’S METHOD......Page 54
1.5.1 Effective Fickian diffusivity......Page 56
1.5.2 Intuitive understanding of the diffusion theory......Page 58
1.5.3 Drying of foods simulated using the effective Fickian
diffusion law......Page 60
1.5.4 Alternative effective diffusion theories......Page 62
1.6 DRIERS......Page 66
1.7 CONCLUDING REMARKS......Page 67
1.8 NOTATION......Page 68
APPENDIX II: ON THE ‘EFFECTIVENESS’ OF THE EFFECTIVE
MOISTURE DIFFUSIVITY BENCHMARKED AGAINST THE
LUIKOV THEORY......Page 70
REFERENCES......Page 76
2.1 INTRODUCTION......Page 79
2.1.1 Thermodynamics of water activity......Page 80
2.1.2 Definition and significance......Page 81
2.1.4 Hysteresis in sorption isotherms......Page 82
2.2.1 Raoult’s Law......Page 83
2.2.2 Norrish model......Page 84
2.2.3 Ross model......Page 85
2.2.4 Money–Born equation......Page 86
2.2.5 Grover model......Page 87
2.2.6 Salwin equation......Page 88
2.3.1 Two-parameter models......Page 89
2.3.2 Three-parameter isotherms......Page 92
2.3.3 Effect of temperature on water activity......Page 97
2.4 TYPES OF SORPTION ISOTHERMS AND HYSTERESIS IN
ISOTHERMS......Page 99
2.5.1 Gravimetric method......Page 102
2.5.2 Manometric method......Page 107
2.5.4 Sample preparation and equilibrium time......Page 108
REFERENCES......Page 110
3.1 INTRODUCTION TO DRYING AND FOOD QUALITY......Page 114
3.2 POST-DRYING PROBLEMS......Page 115
3.3 IN-DRYING PROBLEMS......Page 119
3.4 FOOD BIO-DETERIORATION BY DRYING – A SUB-CELL
LEVEL APPROACH......Page 130
3.5 CONCLUDING REMARKS......Page 132
REFERENCES......Page 133
4.1 INTRODUCTION......Page 137
4.2 BASIC CONCEPTS OF SPRAY DRYING......Page 138
4.3.1 Drying gas supply and heating system......Page 141
4.3.2 Atomization system......Page 142
4.3.3 Drying chamber......Page 145
4.3.4 Powder separators......Page 146
4.4.1 Fundamentals of droplet drying......Page 149
4.4.2 Drying kinetics......Page 150
4.4.3 Residence time......Page 153
4.5.1 Overall mass balance......Page 154
4.5.2 Overall heat balance......Page 157
4.6.1 Thermal efficiency......Page 158
4.6.3 Volumetric evaporative capacity......Page 160
4.7.1 Particle micro-structure......Page 161
4.7.2 Particle morphology......Page 163
4.7.3 Physical and functional properties of powder......Page 165
4.7.4 Drying parameters......Page 171
4.8.1 Dairy powders......Page 173
4.8.2 Micro-encapsulated powders......Page 175
4.8.3 Sugar-rich products......Page 177
4.8.5 Enzymes......Page 178
4.10 NOTATION......Page 179
REFERENCES......Page 181
5.1 INTRODUCTION......Page 184
5.2 BASIC PRINCIPLES OF SUPERHEATED STEAM DRYING......Page 185
5.3 LOW-PRESSURE SUPERHEATED STEAM DRYING OF
FOODS AND BIOMATERIALS......Page 187
5.4 SOME ADVANCES IN LPSSD OF FOODS AND
BIOMATERIALS......Page 201
5.5 MATHEMATICAL MODELING OF LPSSD OF FOODS AND
BIOMATERIALS......Page 206
5.6 CONCLUDING REMARKS......Page 210
REFERENCES......Page 211
6.1 INTRODUCTION......Page 214
6.3 FUNDAMENTALS OF HEAT PUMP DRIERS......Page 215
6.4 HEAT AND MASS TRANSFER MECHANISMS......Page 221
6.5 OPTIMUM USE OF HEAT PUMPS IN DRYING SYSTEMS......Page 234
6.6 INNOVATIVE HEAT PUMP DRYING SYSTEMS......Page 236
6.6.1 Multi-stage compression heat pump drying......Page 237
6.6.2 Cascade heat pump drying systems......Page 238
6.6.3 Heat pump drying systems with multiple evaporators in
series and in parallel......Page 239
6.6.4 Vapor absorption heat pump drier......Page 241
6.7 CLOSING REMARKS......Page 245
6.8 NOTATION......Page 246
REFERENCES......Page 247
7.2 STATES OF WATER......Page 249
7.3 FOOD AND AIR PROPERTIES IN RELATION TO VACUUM
AND FREEZE-DRYING......Page 251
7.4 HEAT TRANSFER MECHANISMS AT LOW PRESSURES......Page 256
7.5 VACUUM DRYING: PRINCIPLES AND DEHYDRATION
MODELS......Page 258
7.6 FREEZE DRYING: PRINCIPLES AND DEHYDRATION
MODELS......Page 260
7.7 ILLUSTRATIVE EXAMPLE......Page 263
7.8 ADVANCES IN VACUUM AND FREEZE DRYING OF
FOODS......Page 267
7.10 NOTATION......Page 269
REFERENCES......Page 270
8.2 STATE DIAGRAM AND STABILITY CONCEPTS OF DRIED
PRODUCTS......Page 276
8.3.1 Microbial quality......Page 279
8.3.2 Chemical changes and quality......Page 281
8.3.3 Physical changes and quality......Page 284
REFERENCES......Page 289
9.1.1 Disturbance variables......Page 294
9.1.3 Examples......Page 295
9.2.1 Controlled variables......Page 296
9.3.1 Plant-wide control strategy configuration......Page 297
9.3.2 Common loops and examples......Page 298
9.4.1 After something happens – feedback control......Page 300
9.4.2 As something happens – feed-forward/predictive control......Page 302
9.5.1 PID feedback control and tuning......Page 303
9.6 HOW TO DO ADVANCED CONTROL (ADVANCED
CONTROL METHODS)......Page 316
9.6.1 Model predictive control (MPC)......Page 317
9.6.3 Artificial intelligence in control......Page 319
REFERENCES......Page 321
10.1.1 Conditions for an explosion to occur......Page 323
10.1.3 What affects the degree of violence of a dust explosion?......Page 324
10.2 A PRACTICAL EXAMPLE: MILK POWDER PLANT SAFETY......Page 325
10.2.1 Fires......Page 326
10.2.2 Explosion protection......Page 334
10.4 THE HUMAN FACTORS......Page 338
REFERENCES......Page 340
Index......Page 343
Color Plate
......Page 347