Introduction to food engineering

Front Cover......Page 1
Introduction to Food Engineering......Page 4
Copyright Page......Page 5
Contents......Page 6
About the Authors......Page 18
Foreword......Page 20
Preface......Page 22
1.1 Dimensions......Page 26
1.2.1 Base Units......Page 27
1.2.2 Derived Units......Page 28
1.2.3 Supplementary Units......Page 29
1.3 System......Page 35
1.4 State of a System......Page 36
1.4.1 Extensive Properties......Page 37
1.5 Density......Page 38
1.6 Concentration......Page 40
1.7 Moisture Content......Page 42
1.8 Temperature......Page 45
1.9 Pressure......Page 47
1.11 Equation of State and Perfect Gas Law......Page 51
1.12 Phase Diagram of Water......Page 52
1.13 Conservation of Mass......Page 54
1.13.1 Conservation of Mass for an Open System......Page 55
1.14 Material Balances......Page 57
1.15 Thermodynamics......Page 66
1.16.2 Second Law of Thermodynamics......Page 67
1.17 Energy......Page 68
1.19.1 Heat......Page 70
1.19.2 Work......Page 71
1.19.2.1 Work Due to a Moving Boundary......Page 72
1.19.2.3 Work Due to Change in Velocity......Page 74
1.19.2.4 Work Due to Shaft Rotation......Page 75
1.19.2.6 Energy Balance......Page 76
Heating at constant pressure involving phase change......Page 78
1.20 Energy Balance for an Open System......Page 80
1.21 A Total Energy Balance......Page 81
1.23 Area......Page 84
Problems......Page 85
List of Symbols......Page 88
Bibliography......Page 89
2 Fluid Flow in Food Processing......Page 90
2.1.1 Pipes for Processing Plants......Page 91
2.1.2.1 Centrifugal Pumps......Page 93
2.1.2.2 Positive Displacement Pumps......Page 96
2.2.1 Terminology Used in Material Response to Stress......Page 97
2.2.3 Viscosity......Page 98
2.3 Handling Systems for Newtonian Liquids......Page 106
2.3.1 The Continuity Equation......Page 107
2.3.2 Reynolds Number......Page 109
2.3.3 Entrance Region and Fully Developed Flow......Page 113
2.3.4 Velocity Profile in a Liquid Flowing Under Fully Developed Flow Conditions......Page 115
2.3.5 Forces Due to Friction......Page 121
2.4 Force Balance on a Fluid Element Flowing in a Pipe—Derivation of Bernoulli Equation......Page 125
2.5 Energy Equation for Steady Flow of Fluids......Page 132
2.5.2 Kinetic Energy......Page 136
2.5.4.1 Energy Loss Due to Sudden Contraction,  Ef,contraction......Page 138
2.5.4.3 Energy Losses Due to Pipe Fittings......Page 139
2.5.5 Power Requirements of a Pump......Page 141
2.6.1 Centrifugal Pumps......Page 145
2.6.3 Pump Performance Characteristics......Page 147
2.6.4 Pump Characteristic Diagram......Page 151
2.6.5 Net Positive Suction Head......Page 152
2.6.6 Selecting a Pump for a Liquid Transport System......Page 156
2.6.7 Affinity Laws......Page 161
2.7 Flow Measurement......Page 162
2.7.1 The Pitot Tube......Page 166
2.7.2 The Orifice Meter......Page 168
2.7.4 Variable-Area Meters......Page 172
2.7.5 Other Measurement Methods......Page 173
2.8.1 Capillary Tube Viscometer......Page 174
2.8.2 Rotational Viscometer......Page 176
2.8.3 Influence of Temperature on Viscosity......Page 179
2.9.1 Properties of Non-Newtonian Fluids......Page 181
2.9.3 Volumetric Flow Rate of a Power Law Fluid......Page 188
2.9.5 Friction Factor and Generalized Reynolds Number for Power Law Fluids......Page 189
2.9.6 Computation of Pumping Requirement of Non-Newtonian Liquids......Page 192
2.10 Transport of Solid Foods......Page 195
2.10.1.1 Bulk Density......Page 196
2.10.1.2 Particle Density......Page 197
2.10.1.3 Particle Size and Size Distribution......Page 198
2.10.1.4 Particle Flow......Page 200
2.10.2 Flow of Granular Foods......Page 201
2.11 Process Controls in Food Processing......Page 204
2.11.1 Processing Variables and Performance Indicators......Page 206
2.11.3.1 Control Strategy......Page 208
2.11.3.2 Feed Backward Control System......Page 209
2.11.3.3 Feedforward Control System......Page 210
2.11.3.4 Stability and Modes of Control Functions......Page 211
2.11.3.5 On-Off Control......Page 212
2.11.3.6 Proportional Controller......Page 213
2.11.3.10 Final Control Element......Page 214
2.12.1 Temperature......Page 216
2.12.2 Liquid Level in a Tank......Page 218
2.12.3 Pressure Sensors......Page 219
2.12.4 Flow Sensors......Page 220
2.13 Dynamic Response Characteristics of Sensors......Page 221
Problems......Page 225
List of Symbols......Page 230
Bibliography......Page 232
3.1 Generation of Steam......Page 236
3.1.1 Steam Generation Systems......Page 237
3.1.2 Thermodynamics of Phase Change......Page 240
3.1.3 Steam Tables......Page 243
3.1.4 Steam Utilization......Page 249
3.2 Fuel Utilization......Page 253
3.2.1 Systems......Page 255
3.2.2 Mass and Energy Balance Analysis......Page 256
3.2.3 Burner Efficiencies......Page 258
3.3 Electric Power Utilization......Page 259
3.3.1 Electrical Terms and Units......Page 261
3.3.2 Ohm’s Law......Page 262
3.3.3 Electric Circuits......Page 263
3.3.4 Electric Motors......Page 265
3.3.5 Electrical Controls......Page 266
3.3.6 Electric Lighting......Page 267
3.4 Energy, Water and Environment......Page 269
3.4.1 Life Cycle Assessment......Page 270
3.4.2 Food System Applications......Page 274
Problems......Page 282
List of Symbols......Page 286
Bibliography......Page 287
4 Heat Transfer in Food Processing......Page 290
4.1.1 Plate Heat Exchanger......Page 291
4.1.2 Tubular Heat Exchanger......Page 295
4.1.3 Scraped-Surface Heat Exchanger......Page 296
4.1.4 Steam-Infusion Heat Exchanger......Page 298
4.1.5 Epilogue......Page 299
4.2.1 Specific Heat......Page 300
4.2.2 Thermal Conductivity......Page 303
4.2.3 Thermal Diffusivity......Page 305
4.3.1 Conductive Heat Transfer......Page 307
4.3.2 Convective Heat Transfer......Page 310
4.3.3 Radiation Heat Transfer......Page 312
4.4 Steady-State Heat Transfer......Page 313
4.4.1 Conductive Heat Transfer in a Rectangular Slab......Page 314
4.4.1.1 Thermal Resistance Concept......Page 315
4.4.2 Conductive Heat Transfer through a Tubular Pipe......Page 317
4.4.3.1 Composite Rectangular Wall (in Series)......Page 320
4.4.3.2 Composite Cylindrical Tube (in Series)......Page 323
4.4.4 Estimation of Convective Heat-Transfer Coefficient......Page 328
4.4.4.1 Forced Convection......Page 333
Turbulent flow in pipes......Page 334
Flow past immersed objects......Page 335
4.4.4.2 Free Convection......Page 340
4.4.4.3 Thermal Resistance in Convective Heat Transfer......Page 344
4.4.5 Estimation of Overall Heat-Transfer Coefficient......Page 345
4.4.6 Fouling of Heat Transfer Surfaces......Page 349
4.4.7 Design of a Tubular Heat Exchanger......Page 355
4.4.8.1 Heat Capacity Rate Ratio, C*......Page 363
4.4.8.2 Heat Exchanger Effectiveness, εE......Page 364
4.4.8.3 Number of Transfer Units, NTU......Page 365
4.4.9 Design of a Plate Heat Exchanger......Page 368
4.4.10 Importance of Surface Characteristics in Radiative Heat Transfer......Page 375
4.4.11 Radiative Heat Transfer between Two Objects......Page 377
4.5 Unsteady-State Heat Transfer......Page 380
4.5.1 Importance of External versus Internal Resistance to Heat Transfer......Page 382
4.5.2 Negligible Internal Resistance to Heat Transfer (NBi<0.1)—A Lumped System Analysis......Page 383
4.5.3 Finite Internal and Surface Resistance to Heat Transfer (0.1≤NBi≤40)......Page 388
4.5.5 Finite Objects......Page 391
4.5.6 Procedures to Use Temperature–Time Charts......Page 393
4.5.7 Use of fh and j Factors in Predicting Temperature in Transient Heat Transfer......Page 401
4.6 Electrical Conductivity of Foods......Page 409
4.7 Ohmic Heating......Page 412
4.8 Microwave Heating......Page 414
4.8.1 Mechanisms of Microwave Heating......Page 415
4.8.2 Dielectric Properties......Page 416
4.8.3 Conversion of Microwave Energy into Heat......Page 417
4.8.4 Penetration Depth of Microwaves......Page 418
4.8.5 Microwave Oven......Page 420
4.8.6.2 Frozen Foods......Page 421
4.8.6.4 Food Composition......Page 422
Problems......Page 423
List of Symbols......Page 439
Bibliography......Page 442
5.1 Processing Systems......Page 446
5.1.1 Pasteurization and Blanching Systems......Page 447
5.1.2.1 Batch Systems......Page 449
5.1.2.2 Continuous Retort Systems......Page 451
5.1.2.4 Aseptic Processing Systems......Page 452
5.1.3 Ultra-High Pressure Systems......Page 453
5.1.4 Pulsed Electric Field Systems......Page 455
5.2 Microbial Survivor Curves......Page 456
5.3 Influence of External Agents......Page 461
5.4 Thermal Death Time F......Page 465
5.5 Spoilage Probability......Page 466
5.6 General Method for Process Calculation......Page 467
5.6.1 Applications to Pasteurization......Page 469
5.6.2 Commercial Sterilization......Page 472
5.6.3 Aseptic Processing and Packaging......Page 475
5.6.4 Combined Processes......Page 483
5.7 Mathematical Methods......Page 485
5.7.1 Pouch Processing......Page 489
Problems......Page 492
List of Symbols......Page 496
Bibliography......Page 497
6 Refrigeration......Page 500
6.1 Selection of a Refrigerant......Page 501
6.2 Components of a Refrigeration System......Page 505
6.2.1 Evaporator......Page 506
6.2.2 Compressor......Page 508
6.2.3 Condenser......Page 511
6.2.4 Expansion Valve......Page 513
6.3 Pressure–Enthalpy Charts......Page 515
6.3.1 Pressure–Enthalpy Tables......Page 520
Liquid enthalpy......Page 521
Enthalpy change in isentropic compression with no vapor superheat at suction......Page 522
6.4.1 Cooling Load......Page 525
6.4.4 Evaporator......Page 526
6.4.6 Refrigerant Flow Rate......Page 527
6.5.1 Flash Gas Removal System......Page 537
Problems......Page 542
List of Symbols......Page 544
Bibliography......Page 545
7 Food Freezing......Page 546
7.1.1.1 Plate Freezers......Page 547
7.1.1.2 Air-Blast Freezers......Page 550
7.1.1.3 Freezers for Liquid Foods......Page 551
7.1.2 Direct-Contact Systems......Page 552
7.1.2.1 Air Blast......Page 553
7.1.2.2 Immersion......Page 554
7.2.1 Density......Page 555
7.2.3 Enthalpy......Page 556
7.2.5 Apparent Thermal Diffusivity......Page 558
7.3 Freezing Time......Page 559
7.3.1 Plank’s Equation......Page 561
7.3.3 Pham’s Method to Predict Freezing Time......Page 565
7.3.4 Prediction of Freezing Time of Finite-Shaped Objects......Page 569
7.3.6 Factors Influencing Freezing Time......Page 573
7.3.8 Thawing Time......Page 574
7.4.1 Quality Changes in Foods during Frozen Storage......Page 577
Problems......Page 581
List of Symbols......Page 585
Bibliography......Page 586
8 Evaporation......Page 590
8.1 Boiling-Point Elevation......Page 592
8.2.1 Batch-Type Pan Evaporator......Page 594
8.2.3 Rising-Film Evaporator......Page 595
8.2.5 Rising/Falling-Film Evaporator......Page 596
8.2.7 Agitated Thin-Film Evaporator......Page 598
8.3 Design of a Single-Effect Evaporator......Page 601
8.4 Design of a Multiple-Effect Evaporator......Page 606
8.5.1 Thermal Recompression......Page 612
Problems......Page 613
Bibliography......Page 616
9.1.1 Composition of Air......Page 618
9.1.4 Enthalpy of Dry Air......Page 619
9.2.2 Specific Heat of Water Vapor......Page 620
9.3.2 Dew-Point Temperature......Page 621
9.3.3 Humidity Ratio (or Moisture Content)......Page 622
9.3.5 Humid Heat of an Air–Water Vapor Mixture......Page 623
9.3.7 Adiabatic Saturation of Air......Page 624
9.3.8 Wet Bulb Temperature......Page 626
9.4.1 Construction of the Chart......Page 629
9.4.2.1 Heating (or Cooling) of Air......Page 631
9.4.2.2 Mixing of Air......Page 633
9.4.2.3 Drying......Page 635
Problems......Page 636
List of Symbols......Page 639
Bibliography......Page 640
10 Mass Transfer......Page 642
10.1 The Diffusion Process......Page 643
10.1.1 Steady-State Diffusion of Gases (and Liquids) through Solids......Page 646
10.1.2 Convective Mass Transfer......Page 647
10.1.3 Laminar Flow Over a Flat Plate......Page 651
10.1.5 Laminar Flow in a Pipe......Page 655
10.1.7 Mass Transfer for Flow Over Spherical Objects......Page 656
10.2 Unsteady-State Mass Transfer......Page 657
10.2.1 Unsteady-State Diffusion......Page 658
10.2.2 Diffusion of Gases......Page 663
Problems......Page 666
List of Symbols......Page 668
Bibliography......Page 669
11 Membrane Separation......Page 670
11.1 Electrodialysis Systems......Page 672
11.2 Reverse Osmosis Membrane Systems......Page 676
11.3 Membrane Performance......Page 683
11.4 Ultrafiltration Membrane Systems......Page 684
11.5 Concentration Polarization......Page 686
11.6 Types of Reverse-Osmosis and Ultrafiltration Systems......Page 692
11.6.3 Spiral-Wound......Page 693
Problems......Page 696
List of Symbols......Page 697
Bibliography......Page 699
12.1 Basic Drying Processes......Page 700
12.1.1 Water Activity......Page 701
12.1.2 Moisture Diffusion......Page 704
12.1.4 Heat and Mass Transfer......Page 705
12.2.1 Tray or Cabinet Dryers......Page 707
12.2.2 Tunnel Dryers......Page 708
12.2.3 Puff-Drying......Page 709
12.2.5 Spray Drying......Page 710
12.2.6 Freeze-Drying......Page 711
12.3.1 Mass and Energy Balance......Page 712
12.3.2 Drying-Time prediction......Page 717
Problems......Page 727
List of Symbols......Page 732
Bibliography......Page 733
13.1.1 Operating Equations......Page 736
13.1.1.1 Constant-Rate Filtration......Page 738
13.1.1.2 Constant-Pressure Filtration......Page 740
13.1.2 Mechanisms of Filtration......Page 742
13.1.3 Design of a Filtration System......Page 743
13.2.1 Sedimentation Velocities for Low-Concentration Suspensions......Page 746
13.2.2 Sedimentation in High-Concentration Suspensions......Page 749
13.3.2 Rate of Separation......Page 752
13.3.3 Liquid-Liquid Separation......Page 754
13.4 Mixing......Page 756
13.4.1 Agitation Equipment......Page 758
13.4.1.1 Marine-type Propeller Impellers......Page 759
13.4.1.2 Paddle Impellers......Page 760
13.4.2 Power Requirements of Impellers......Page 761
Problems......Page 765
List of Symbols......Page 766
Bibliography......Page 767
14.1 Introduction and Background......Page 768
14.2 Basic Principles of Extrusion......Page 769
14.3 Extrusion Systems......Page 776
14.3.1 Cold Extrusion......Page 777
14.3.2 Extrusion Cooking......Page 778
14.3.3 Single Screw Extruders......Page 779
14.3.4 Twin-Screw Extruders......Page 781
14.4 Extrusion System Design......Page 782
14.5 Design of More Complex Systems......Page 787
Problems......Page 788
List of Symbols......Page 789
Bibliography......Page 790
15.1 Introduction......Page 792
15.2 Food Protection......Page 793
15.3 Product Containment......Page 794
15.6 Mass Transfer in Packaging Materials......Page 795
15.6.1 Permeability of Packaging Material to “Fixed” Gases......Page 798
15.7 Innovations in Food Packaging......Page 801
15.7.2.2 Advanced Active......Page 802
15.7.3 Intelligent Packaging......Page 803
15.7.3.1 Simple Intelligent......Page 804
15.8.1 Scientific Basis for Evaluating Shelf Life......Page 805
15.8.1.1 Zero-Order Reaction......Page 806
15.8.1.2 First-Order Reaction......Page 807
Problems......Page 813
List of Symbols......Page 814
Bibliography......Page 815
Table A.1.1 SI Prefixes......Page 818
Table A.1.2 Useful Conversion Factors......Page 821
Table A.1.3 Conversion Factors for Pressure......Page 823
Table A.2.1 Specific Heat of Foods......Page 824
Table A.2.2 Thermal Conductivity of Selected Food Products......Page 825
Table A.2.3 Thermal Diffusivity of Some Foodstuffs......Page 827
Table A.2.4 Viscosity of Liquid Foods......Page 828
Table A.2.6 Approximate Heat Evolution Rates of Fresh Fruits and Vegetables When Stored at Temperatures Shown......Page 829
Table A.2.7 Enthalpy of Frozen Foods......Page 831
Table A.2.8 Composition Values of Selected Foods......Page 832
Table A.2.9 Coefficients to Estimate Food Properties......Page 833
Table A.3.1 Physical Properties of Metals......Page 834
Table A.3.2 Physical Properties of Nonmetals......Page 835
Table A.3.3 Emissivity of Various Surfaces......Page 837
Table A.4.1 Physical Properties of Water at the Saturation Pressure......Page 839
Table A.4.2 Properties of Saturated Steam......Page 840
Table A.4.3 Properties of Superheated Steam......Page 842
Table A.4.4 Physical Properties of Dry Air at Atmospheric Pressure......Page 843
Figure A.5.1 Psychrometric chart for high temperatures......Page 844
Figure A.5.2 Psychrometric chart for low temperatures......Page 845
Figure A.6.1 Pressure–enthalpy diagram for Refrigerant 12......Page 846
Table A.6.1 Properties of Saturated Liquid and Vapor R-12......Page 847
Figure A.6.2 Pressure–enthalpy diagram of superheated R-12 vapor......Page 850
Table A.6.2 Properties of Saturated Liquid and Vapor R-717 (Ammonia)......Page 851
Figure A.6.3 Pressure–enthalpy diagram of superheated R-717 (ammonia) vapor......Page 854
Table A.6.3 Properties of Saturated Liquid and Vapor R-134a......Page 855
Figure A.6.4 Pressure–enthalpy diagram of R-134a......Page 858
Figure A.6.5 Pressure–enthalpy diagram of R-134a (expanded scale)......Page 859
A.7 Symbols for use in Drawing Food Engineering Process Equipment......Page 860
Table A.8.1 Numerical Data and Area/Volume of Objects......Page 865
Figure A.8.1 Temperature at the geometric center of a sphere (expanded scale)......Page 866
Figure A.8.2 Temperature at the axis of an infinitely long cylinder (expanded scale)......Page 867
Figure A.8.3 Temperature at the midplane of an infinite slab (expanded scale)......Page 868
A.9.1 Buckingham π Theorem......Page 869
Table A.9.1 Dimensions of Selected Experimental Variables......Page 870
Bibliography......Page 873
Index......Page 876
Food Science and Technology International Series......Page 888