Engineering properties of food

Preface The Editors Contri butors Chapter 1 Mass-Volume-Area-Related Properties of Foods 1 M. Shafiur Rahman I. Introduction 1 II. Fundamental Considerations 2 A. Volume 2 1. Boundary Volume 2 2. Pore Volume 2 B. Density 2 1. True Density 2 2. Material Density 3 3. Particle Density 3 4. Apparent Density 4 5. Bulk Density 4 C. Porosity 4 1. Open Pore Porosity 4 2. Closed Pore Porosity 4 3. Apparent Porosity 5 4. Bulk Porosity 5 5. Bulk-Particle Porosity 5 6. Total Porosity 5 D. Surface Area 5 E. Pore Size Distribution 6 III. Measurement Techniques 6 A. Density Measurement 6 1. Apparent Density 6 2. Material Density 11 3. Particle Density 14 4. Bulk Density 14 ix - -------------- x Rao, Rizvi, and Datta B. Measurement Techniques of Porosity 14 1. Direct Method 14 2. Optical Microscopic Method 14 3. Density Method 14 C. Surface Area 15 1. Boundary Surface Area 15 2. Pore Surface Area 15 3. Cross-Sectional Area 16 IV Specific Data 16 A. Predictions of Density 16 1. Gases and Vapors 17 2. Liquid Foods 18 3. Density of Solid Foods 19 B. Predictions of Porosity 22 C. Prediction of Surface Area 25 1. Euclidian Geometry 25 2. Non-Euclidian or Irregular Geometry 26 3. Theoretical Prediction 26 4. Size Distribution 30 V. Summary 33 Acknowledgments 33 List of Symbols 33 Greek Symbols 34 Subscripts 34 Superscripts 35 References 35 Chapter 2 M. A. Rao I. Introduction 41 II. Rheological Classification of Fluid Foods 42 A. Rheological Models for Viscous Foods 47 1. Models for Time-Independent Behavior 47 2. Rheological Models for Thixotropic Foods 51 3. Effect of Temperature on Viscosity 52 4. Combined Effect of Temperature and Shear Rate 54 5. Effect of Concentration on Viscosity 54 B. Rheological Models for Viscoelastic Fluid Foods 56 1. Normal Stress Data on Fluid Foods 56 2. Creep Compliance Studies on Foods 57 III. Structure of Fluid Foods via Solution Viscosity and Physicochemical Approach 59 A. Solution Viscosity 60 B. Physicochemical Approach 61 IV. Measurement of Flow Properties of Fluid Foods 61 A. Fundamental Methods 61 1. Capillary Flow 61 2. Couette Flow Viscometers 63 3. Plate-and-Cone Viscometers 65 Rheological Properties of Fluid Foods 41 Table of Contents xi 4. Parallel Plate Geometry 66 5. Slit (Channel) Rheometers 67 6. Extensional Flows 68 B. Empirical Methods 71 1. Adams Consistometer 71 2. Bostwick Consistometer 71 3. Efflux Tube Viscometer 72 C. Imitative Methods 72 1. Mixers for Determining Flow Properties 73 2. In-Plant Measurement of Rheological Behavior of Fluid Foods 77 V. Flow of Fluid Foods in Tubes 81 A. Isothermal Flow of Fluids in Tubes 82 1. Velocity Profiles and Volumetric Flow Rate Relationships 82 2. Friction Losses for Power Law Foods in Pipes 83 3. Pressure Drop Across Valves and Fittings 87 4. Friction Losses for Herschel-Bulkley Fluids 87 5. Calculation of Kinetic Energy for Non-Newtonian Fluids 88 VI. Conclusion 89 List of Symbols 89 Greek Symbols 90 Subscripts 91 Superscript 91 References 91 Chapter 3 Rheological Properties of Solid Foods 101 V. N Mohan Rao and Ximena Quintero I. Introduction 101 II. Quasistatic Tests for Solid Foods 102 A. Introduction 102 B. Some Simple Tests 104 C. Rheological Modeling 108 D. Creep 109 E. Relaxation 111 III. Dynamic Testing of Solid Foods 113 A. Introduction 113 B. Theoretical Considerations 114 1. Resonance 114 2. Direct Stress-Strain Tests 11 7 C. Application of Resonance 120 D. Application of Direct Stress-Strain Tests 123 IV. Failure and Glass Transition in Solid Foods 126 A. Failure in Solid Foods 126 B. Glass Transition of Solid Foods 128 1. Factors that Affect Glass Transition 129 2. Measurement of Glass Transition 129 3. Importance of Glass Transition in Solid Foods 131 V. Empirical and Imitative Tests 132 A. Introduction 132 B. Texture Profile Analysis 133 ------ xii Rao, Rizvi, and Datta C. Texture (Shear) Press 135 D. Warner-Bratzler Shear 136 E. FMC Pea Tenderometer 136 F. Penetrometer 137 G. Other Empirical Methods 137 VI. Conclusions 138 References 139 Chapter 4 Thermal Properties of Unfrozen Foods 149 Paul Nesvadba I. Introduction 149 A. The Importance of Thermal Properties for the Quality and Safety of Foods 149 B. Modeling and Optimization of Processes 150 II. Sources of Data on Thermal Properties 151 A. Measurement 151 B. Literature 151 C. Computerized and On-Line Databases 151 D. Software for Predicting Thermal Properties of Foods 152 III. Density 152 A. Definition of Powder Bulk Density 154 IV. Specific Heat Capacity 154 A. Latent Heat of Melting 156 B. Specific and Latent Heat of Fats 156 V. Thermal Conductivity 157 A. Predictive Equations 157 B. Influence of Structure of Food on Thermal Conductivity 160 VI. Measurement Methods for Thermal Conductivity 16 A. The Basis of Operation of the Needle Probe 161 B. Reference Materials 165 VII. Other Properties Relevant to Thermal Processing of Foods 165 A. Compressibility and Thermal Expansion 165 B. Glass Transitions 166 C. Sorption and Hydration Properties 167 VIII. Conclusions 167 Symbols, Names, and Dimensions 167 References 168 Chapter 5 Thermal Properties of Frozen Foods 175 R. Paul Singh and Amab Sarkar I. Introduction 175 II. Experimental Approaches to Measuring the Thermal Properties of Frozen Foods 176 A. Initial Freezing Point and Unfrozen Water 176 B. Density 177 C. Thermal Conductivity 177 D. Enthalpy 177 Table of Contents xiii E. Specific Heat 178 F. Thermal Diffusivity 178 III. General Observations on the Reliability of Experimental Data 181 IV. Modeling of the Thermal Properties of Frozen Foods 184 A. Prediction of Unfrozen Water During Freezing of Foods 184 1. Density 189 2. Thermal Conductivity 190 3. Enthalpy 194 4. Apparent Specific Heat 197 B. Limitations of Predictive Models 199 List of Symbols 200 Greek Symbols 200 Subscripts 201 References 201 Chapter 6 Properties Relevant to Infrared Heating of Foods 209 Ashim K. Datta and Marialuci Almeida I. Introduction 209 II. Fundamentals of Infrared Interactions with Materials 210 A. Electromagnetic Spectrum and Near-, Mid- and Far-Infrared Electromagnetic Waves 210 B. Interaction between Infrared Radiation and Food Materials 210 C. Sources of Infrared Radiation in Heating Applications 212 D. Emission and Emissivity 212 E. Reflection, Absorption, and Transmission 214 F. Absorptivity and Emissivity 218 G. Attenuation or Extinction 219 III. Use of the Radiative Properties in Modeling of Heat Transfer 220 IV. Measurement of Radiative Properties of Foods 221 V. Radiative Property Data for Food Systems 224 A. Radiative Property Data for Water, Ice, and Water Vapor 224 B. Properties of Other Pure Food Components 225 C. Spectral Variation of Radiative Property Data: Potato Tissue as an Example 225 D. Moisture Dependence of Radiative Property Data 227 E. Temperature Dependence of Radiative Property Data 228 F. Dependence of Radiative Property Data on Food Structure 230 G. How Processing Can Change Food Radiative Properties 232 H. Summary: Use of Radiative Property Data in Modeling 234 Acknowledgments 235 References 235 Chapter 7 Thermodynamic Properties of Foods in Dehydration 239 S. S. H. Rizvi I. Introduction 239 II. Thermodynamics of Food-Water Systems 240 A. Chemical Potential and Phase Equilibria 242 B. Fugacity and Activity 244 xiv Rao, Rizvi, and Datta C. Water Activity in Foods 246 D. Measurement of Water Activity 252 1. Measurements Based on Colligative Properties 252 2. Measurements Based on Psychrometry 255 3. Measurements Based on Isopiestic Transfer 256 4. Measurements Based on Suction (Matric) PotentiaL 256 E. Adjustment of Water Activity 256 F. Moisture Sorption Isotherms 261 1. Theoretical Description of MSls 261 2. Effect of Temperature.. 268 III. Sorption Energetics 272 A. Differential Quantities 273 B. Integral Quantities 276 D. Hysteresis and Irreversibility 281 E. Kinetic Aspects 287 IV. Dehydration Principles and Processes 288 A. Drying Behavior 290 B. Constant-Rate Period 293 C. Falling-Rate Period 295 D. Equilibrium Moisture Content 301 E. Energy Requirements 304 V. Conclusion 307 List of Symbols 308 Greek Symbols 309 Subscripts 310 Superscripts 310 References 310 Chapter 8 Mass Transfer Properties of Foods 327 George D. Saravacos 1. Introduction 327 II. Phase Equilibria 329 A. Vapor-Liquid Equilibria 329 B. Gas-Liquid Equilibria 333 C. Liquid-Liquid and Liquid-Solid Equilibria 335 D. Gas-Solid and Vapor-Solid Equilibria 336 Water Activity 336 III. Diffusion 338 A. Diffusion in Gases 339 B. Diffusion in Liquids 340 C. Diffusion in Solids 341 1. Introduction 341 2. Diffusion in Polymers 343 3. Molecular Simulations 344 D. Estimation of Diffusivity in Solids 345 1. Sorption Kinetics 345 2. Permeation Measurements 346 3. Distribution of Penetrant 347 4. Drying Rate 349 Table of Contents xv IV. Interphase Mass Transfer 349 A. Mass Transfer Coefficients 349 B. Penetration Theory 351 C. Analogies of Heat and Mass Transfer 352 D. Effect of Surfactants 353 V. Mass Transfer in Foods 354 A. Moisture Transport 354 1. Moisture Diffusion 354 2. Diffusion in Porous Foods 356 3. Interphase Moisture Transfer 360 B. Diffusion of Solutes 360 C. Diffusion of Aroma Compounds 362 VI. Other Mass Transfer Processes 364 A. Extraction 364 B. Distillation and Gas Absorption 366 C. Crystallization 368 D. Food Packaging 370 Acknowledgments 372 List of Symbols 372 Greek Symbols 373 References 373 Chapter 9 Physicochemical and Engineering Properties of Food in Membrane Separation Processes 381 D. Rana, T. Matsuura, and S. Sourirajan I. Introduction 381 II. Transport Theories 382 A. Case 1: Preferential Sorption of Water at the Membrane- Solution Interface 382 1. Basic Transport Equations 382 2. Relationship between (DAMIKo)NaCI and DAM/KO for Other Solutes 384 3. RO Process Design.. 387 B. Case II: Surface Force-Pore Flow Model; Generation of Interfacial Surface Force Parameters and Their Application 389 1. Analysis Fundamentals 389 2. Quantities Ra, Rb, and d 390 3. Definitions of Dimensionless Quantities 390 4. Basic Transport Equations 391 5. Liquid Chromatography for the Determination of Interfacial Interaction Force Parameters 396 6. Data on Interfacial Surface Force Parameters 397 7. Data on Pore Size and Pore Size Distribution 398 III. Problems in Membrane Separation and Concentration of Liquid Foods 403 A. Application of Water Preferential Sorption ModeL 406 1. Separation of Undissociated Organic Solutes Such as Sugars Present in High Concentration 413 2. Separations of Undissociated Polar Organic Solutes Present in Low Concentrations 413 xvi Rao, Rizvi, and Datta 3. Separation of Partially Dissociated Organic Solutes Present in Low Concentration 416 4. Problem of Separations of Low Concentrations of Undissociated Organic Solutes in Concentrated Sugar Solutions 418 5. Separation of Solutions of Partially Dissociated Acids Present in Concentrated Sugar Solutions 419 B. Application of Transport Equations to Real Fruit Juice Concentration 421 C. Application of Transport Equations for the Concentration of Green Tea Juice 426 D. Some Illustrative Examples of the Surface Force-Pore Flow Model 431 1. Parametric Studies on Solute Separation and Product Rate ...431 2. Another Parametric Study on Solute Concentration Profile and Solution Velocity Profile 434 E. Some Data on the Ultrafiltration of Proteins 437 1. Ultrafiltration of Bovine Serum Albumin (BSA) and a-Casein 437 2. Effects of Fouling on Membrane Performance and Pore Size and Pore Size Distribution 440 3. Fractionation of the Protein-Sugar System and the Protein-Protein System in the Aqueous Solutions 443 F. Application of Pervaporation in the Recovery and Concentration of Food Flavors 445 IV. Recent Literature on Membrane Applications 447 A. Dairy Product Industry 447 1. Reverse Osmosis 447 2. Nanofiltration 448 3. Ultrafiltration 448 4. Microfiltration 448 B. Beverage Industry 449 1. Reverse Osmosis ". 449 2. Ultrafiltration 450 3. Microfiltration 450 C. Edible Oil Industry 450 1. Reverse Osmosis 451 2. Ultrafiltration 451 3. Microfiltration 451 V. Conclusion 452 List of Symbols 453 Greek Symbols..., 454 References 455 Chapter 10 Electrical Conductivity of Foods 461 Sudhir K. Sastry I. Introduction 461 II. Basic Definitions 462 III. Liquid Foods 462 Table of Contents xvii A. Theory of Electrolytic Conductivity 462 1. Strong Electrolytes 464 2. Weak Electrolytes 464 B. Relations between Electrical Conductivity and Other Transport Properties 465 C. Effect of Temperature 466 D. Effect of Electric Field Strength 467 E. Effect of Ingredients 468 1. Electrolytic Solutes 468 2. Inert Suspended Solids 468 3. Hydrocolloids. 469 4. Phase Transitions of Suspended Solids 471 5. Effect of Nonelectrolytic Solutes 474 IV. Solid Foods 474 A. Effect of Microstructure 474 B. Effects of Temperature and Electric Field Strength 475 1. Gels and Noncell ular Solids 4 75 2. Solids with Undisrupted Cellular Structure 476 3. Modeling of Cell Membrane Breakdown 479 4. Reversibility and Repair of Pores 479 5. Extension to Eukaryotic Cells 480 C. Effect of Frequency 482 1. Relation to Dielectric Constant 484 D. Ingredient Effects 487 V. Solid-Liquid Mixtures 488 A. Models for Effective Electrical Conductivity 488 1. Maxwell ModeL 488 2. Meredith and Tobias (1960) Model 489 3. Series Model 489 4. Parallel Model 489 5. Kopelman ModeL 489 6. Probability Model 490 7. Comparison of Models 490 B. Effects of Solids in Tube Flow 490 VI. Methods.of Measurement of Electrical Conductivity 492 List of Symbols 496 Greek Letters and Other Symbols 496 Subscripts/Superscripts Not Explained Elsewhere 497 References 497 Chapter 11 Dielectric Properties of Foods 501 Ashim K. Datta, a. Sumnu, and a.s. v. Raghavan I. Introduction 501 II. Basic Principles 502 A. Radiofrequency vs. Microwave Heating 509 III. Measurement Principles 509 A. Waveguide and Coaxial Transmission Line Methods 510 B. Short-Circuited Line Technique 510 xviii Rao, Rizvi, and Datta C. Open-Ended Probe Technique 511 D. Time Domain Reflectometry (TDR) Method 512 E. Free-Space Transmission Technique 512 F. Microstrip Transmission Line 513 G. Six-Port Reflectometer Using an Open-Ended Coaxial Probe 513 H. Colloid Dielectric Probe (Hewlett Packard) 514 I. Test Cell with Boonton RX-Meter 514 J. Cavity Perturbation Technique 514 1. Solid Sample Preparation 517 2. Liquid Sample Preparation 517 3. Semisolid Samples 517 K. Summary of Dielectric Property Measurement Techniques 517 IV. Frequency and Temperature Dependence 518 A. Frequency Dependence 518 A. Frequency Dependence in Food Materials 521 B. Temperature Dependence in Water, Salt Solutions, and Foods 522 1. Dielectric Properties below Freezing and above Boiling Temperatures 526 2. Temperature Dependence of Loss Factor and Runaway Heating 530 V. Composition Dependence 531 A. Moisture Dependence 531 B. Dielectric Properties of Carbohydrates 533 1. Starch 534 2. Sugar 536 3. Gums 536 C. Dielectric Properties of Proteins 538 D. Dielectric Properties of Fat 541 E. Dielectric Properties of Meats 542 F. Dielectric Properties of Fish and Seafood 543 G. Dielectric Properties of Fruits and Vegetables 545 H. Dielectric Properties of Dairy Products 547 VI. Dielectric Properties of Insect Pests 550 VII. Dielectric Properties of Packaging Materials 551 VIII. Effects of Processing and Storage on Dielectric Properties of Foods... 551 A. Baking 551 B. Drying 554 C. Cooking 554 D. Mixing 554 E. Storage 554 IX. Assessment of Food Quality by Using Dielectric Properties 555 X. Further Sources of Data 557 Acknowledgment 557 References 557 Chapter 12 Ultrasound Properties 567 Michael J. McCarthy, Lu Wang, and Kathryn L. McCarthy I. Introduction 567 II. Fundamentals of Acoustics 569 Table of Contents xix A. Speed of Sound, Density, and Elastic Moduli 569 B. Amplitude and Attenuation 571 1. Scattering 572 2. Absorption 572 C. Impedance, Reflection, and Refraction 573 D. Doppler Shift Frequency and Velocity 574 III. Ultrasonic Measurement Techniques 575 A. Ultrasonic Methods 576 1. Pulsed-Echo 576 2. Pitch-and -Catch 578 3. Interferometry 578 4. Spectral Analysis 579 5. Ultrasonic Imaging 579 B. Transducer Selection 580 C. Interpretation of Ultrasonic Measurements 582 IV. Compilation of Acoustic Properties 582 A. Composition 582 1. Solutions and Beverages 582 2. Concentrated Solutions 587 3. Oils 588 4. Emulsions 589 5. Muscle Foods 593 B. Phase Transitions 594 1. Freezing 594 2. Crystallization of Fats 594 3. Gelation 596 C. Texture 597 1. Firmness of FruitsNegetables 597 2. Cheese 597 3. Starch Products 598 D. Viscosity , 599 1. Viscosity and Attenuation 599 2. Viscosity and UDV 600 V. Conclusion 603 List of Symbols 604 Greek Symbols 604 Subscripts 605 Superscripts 605 References 605 Chapter 13 Kinetic Data for Biochemical and Microbiological Processes during Thermal Processing 611 Ann M. Van Loey, Chantal Smout, Indrawati, and Marc E. Hendrickx I. Introduction 611 II. Fundamental Considerations 614 A. Primary Kinetic Models 615 1. Zero-Order Model 616 2. First-Order Model 617 xx Rao, Rizvi, and Datta 3. Biphasic Model 618 4. Fractional Conversion Mode! 618 B. Secondary Kinetic Models 619 1. Influence of Temperature on the Reaction Rate Constant 619 2. Selection of a Temperature Coefficient Model 620 III. Measurement Techniques 621 IV. Specific Data on Properties 623 A. Microbial Inactivation 623 B. Enzyme Inactivation 625 C. Texture Degradation 626 D. Color Degradation 627 E. Flavor Degradation 629 F. Nutrient Degradation 630 References 633 Chapter 14 Gas Exchange Properties of Fruit and Vegetables 645 Bart M. Nicolai~ Jeroen Lammertyn, Wendy Schotsmans, and Bert E. Verlinden I. In trod uction .. . 645 II. Fundamental Considerations 646 A. Respiration and Fermentation 646 1. Respiration Rate 648 2. Respiration and Fermentation Models 649 3. Gas Transport Properties 653 B. Measurement Techniques 655 1. Oxygen Consumption and Carbon Dioxide Production Rate 655 2. Measurement of O2 and C02 Concentration 656 3. Measurement of Heat of Respiration 659 4. Skin Resistance and Gas Diffusion Properties 660 C. Gas Exchange Data for Selected Fruits and Vegetables 663 III. Applications 663 Acknowledgments 671 List of Symbols 671 References 672 Chapter 15 Surface Properties 679 Joseph McGuire I. Introduction .. ...679 II. Fundamental Considerations 680 A. Definitions 680 B. The Gibbs Adsorption Equation 682 C. The Contact Angle 684 1. Critical Surface Tension 686 2. Polar and Dispersive Contributions to Surface Energy 686 3. An Equation of State Relationship between Interfacial Energies 690 D. Effects of Adsorbed Layer Composition and Structure on Interfacial Energy 690 Table of Contents xx; III. Measurement Techniques 693 A. Evaluation of the Contact Angle 693 B. Evaluation of Liquid Surface Tension 694 C. Evaluation of rl and ri 696 IV Surface Property Data 697 V. Summary 699 References 699 Chapter 16 Colorimetric Properties of Foods 703 F. J. Francis Introduction 703 Physiological Basis of Color 704 Measurement of Color 705 A. Spectrophotometry 705 B. Tristimulus Colorimetry... 711 C. Specialized Colorimeters 712 IV Presentation of Samples 714 V Research and Quality Control Approaches 717 VI. Color Tolerances 720 VII. Development of Instruments 723 VIII. Conclusion 726 References 727 I. II. III. Index 733