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About the IFST Advances in Food Science Book Series xvi List of Contributors xvii Preface xx
Part 1 Fundamentals of Ultrasound 1 1 Basic Principles of Ultrasound 3 Juan A. GallegoJuárez
1.1 Introduction 4
1.2 Generation and Detection of Ultrasonic Waves: Basic Transducer Types 5
1.3 Basic Principles of Ultrasonic Wave Propagation 12
1.4 Basic Principles of Ultrasound Applications 15
1.4.1 Lowintensity Applications 15
1.4.2 Highintensity Effects and Applications: Power Ultrasound 18
1.5 Conclusions 23 Acknowledgments 24 References 24
Part 2 Lowintensity Ultrasound Applications 27 Section
2.1 Food and Process Control 29 2 Ultrasonic Particle Sizing in Emulsions 30 M.J. Holmes and M.J.W. Povey
2.1 Introduction 30
2.2 Definitions: Emulsions and Ultrasound 32
2.3 Theoretical Models of Ultrasound Propagation in Emulsions 35
2.4 Diffraction and Scattering 41
2.5 Multiple Scattering 44
2.6 Mode Conversions 46
2.7 Perturbation Solutions 49
2.8 Twoparticle Models 53
2.9 Practical Particle Sizing Techniques 55
2.10 Conclusion 60 Acknowledgements 60 References 60 3 Ultrasonic Applications in Bakery Products 65 J. Salazar, J.A. Chávez, A. Turó, and M.J. GarciaHernández
3.1 Introduction 65
3.2 Ultrasonic Properties of Materials 67
3.2.1 Ultrasonic Velocity 68
3.2.2 Attenuation 69
3.2.3 Acoustic Impedance 69
3.3 Experimental Setup for Ultrasonic Measurements 70
3.3.1 Bread Dough 70
3.3.2 Cake Batter 71
3.4 Experimental Results and Discussion 71
3.4.1 Wheat Dough 72
3.4.2 Rice Dough 78
3.4.3 Cake Batter 81
3.5 Discussion and Conclusion 82 References 82 4 Characterization of Pork Meat Products using Ultrasound 86 J.V. GarciaPérez, M. De Prados, and J. Benedito
4.1 Introduction 86
4.2 Ultrasonic Measurements: Devices and Parameters 89
4.3 Assessment of Fat Properties 91
4.3.1 Influence of Temperature on Ultrasonic Velocity 91
4.3.2 Classification of Meat Products by means of their Fat Melting/ Crystallization Behavior 92
4.3.3 Monitoring of Fat Melting/Crystallization 97
4.4 Composition Assessment 101
4.5 Textural Properties 104
4.6 New Trends 108 Acknowledgements 110 References 110 5 The Application of Ultrasonics for Oil Characterization 115 P. Kielczynski
5.1 Introduction 116
5.1.1 Classical Methods for the Investigation of Physicochemical Parameters of Oils and Liquid Foodstuffs 117
5.1.2 Ultrasonic Methods 117
5.1.3 Highpressure Physicochemical Properties of Oils 120
5.2 Physicochemical Parameters of Liquids (Oils) that can be Evaluated by means of Ultrasonic Methods 121
5.2.1 Ultrasonic Wave Velocity and Density Measurement 121
5.2.2 Measurement of Sound Velocity, Density, and Liquid Viscosity 124
5.3 Ultrasonic Measurements 125
5.3.1 Sound Velocity 125
5.3.2 Viscosity 128
5.3.3 Attenuation 129
5.4 Measurements of Selected Physicochemical Parameters of Oils at Elevated Pressures and Various Values of Temperature 130
5.4.1 Sound Velocity 131
5.4.2 Density 131
5.4.3 Numerical Approximation of Density and Sound Velocity 131
5.4.4 Adiabatic Compressibility 132
5.4.5 Isothermal Compressibility 133
5.4.6 Isobaric Thermal Expansion Coefficient 134
5.4.7 Specific Heat Capacity 134
5.4.8 Surface Tension 134
5.4.9 Investigation of Highpressure Phase Transitions in Oils by Ultrasonic Methods 135
5.5 Conclusions 138 List of Symbols 139 References 141 6 Bioprocess Monitoring using Lowintensity Ultrasound: Measuring Transformations in Liquid Compositions 146 L. Elvira, P. Resa, P. Castro, S. Kant Shukla, C. Sierra, C. Aparicio, C. Durán, and F. Montero de Espinosa
6.1 Introduction 147
6.2 Physical Models for Bioprocessrelated Media 149
6.2.1 Modelling the Medium 149
6.2.2 Modelling the Bioprocess: Obtaining Information about the Medium Composition 154
6.3 Ultrasonic Measurement Techniques for Bioprocess Monitoring and Instrumentation 156
6.3.1 Measurement Based on Pulsedwave Techniques 156
6.3.2 Measurement Based on Resonance Techniques 158
6.3.3 Control of External Conditions: Temperature and Pressure 161
6.4 Applications of Ultrasonic Technologies to Bioprocess Monitoring 161
6.4.1 Enzymatic Processes 161
6.4.2 Fermentative Processes 165
6.4.3 Microbial Growth 168 References 171 Section
2.2 New Trends in Ultrasonic Nondestructive Testing 175 7 Aircoupled Ultrasonic Transducers 176 T.E. Gomez AlvarezArenas
7.1 Introduction 177
7.1.1 Lowfrequency (100 kHz), Relatively Lowpower Transducers 178
7.2 Highfrequency Transduction Technologies 178
7.2.1 Capacitive Transducers 179
7.2.2 Piezoelectric Transducers 179
7.2.3 Ferroelectret Polymer Film Transducers 182
7.3 Uses and Applications of Highfrequency (>100 kHz) Ultrasonic Aircoupled Transducers 183
7.4 Design Criteria for Highfrequency Aircoupled Transducers 187
7.4.1 Requirements Imposed by the Sample Insertion Loss 187
7.4.2 Main Design Parameters 191
7.5 Design of Wideband and Highfrequency (>100 kHz) Aircoupled Piezoelectric Transducers 196
7.5.1 Materials Selection 196
7.5.2 The Ideal Piezoelectric Aircoupled Transducer 200
7.5.3 The Realistic Piezoelectric Aircoupled Transducer 201
7.5.4 Why can Piezoelectric Transducers not be Designed Following the Optimum Design? 206
7.5.5 Realistic Alternatives for the Design of Aircoupled Piezoelectric Transducers 207
7.5.6 Optimization under Realistic Constraints: The ML Detuning Technique 209
7.6 Highfrequency and Wideband Piezoelectric Transducers: Realizations in the Frequency Range
0.20-2.0 MHz 213
7.7 Focusing Techniques 216
7.7.1 Geometrically Focused Transducer Aperture 217
7.7.2 Fresnel Zone Plates 217
7.7.3 Offaxis Parabolic Mirror 218 References 218 8 Acoustic Microscopy 229 N.J. Watson, M.J.W. Povey, and N.G. Parker
8.1 Introduction 230
8.2 Acoustic Microscope Theory 231
8.3 Acoustic Contrast 232
8.4 Focusing 233
8.5 Spatial Resolution 235
8.6 Temperature Effects 237
8.7 Generation of an Acoustic Image 238
8.8 Components and Operation of an Acoustic Microscope 238
8.8.1 Transducer 238
8.8.2 Sample Unit 242
8.8.3 Positioning System 244
8.8.4 Pulser and Receiver 244
8.8.5 Control Software 244
8.8.6 Sample Preparation and Operating Considerations 244
8.9 Combination of Acoustic Microscopy with other Techniques 245
8.10 Uses of Acoustic Microscopes in the Food Industry 245
8.11 Future Trends for Acoustic Microscopes in the Food Industry 249
8.11.1 Reduced Scanning Time 250
8.11.2 Easier Sample Preparation 250
8.11.3 Nonimmersion Operation 250
8.11.4 Noncontact Scanning 250
8.12 Additional Resources 250 Acknowledgements 250 References 251
Part 3 Highintensity Ultrasound Applications 255 Section
3.1 Ultrasound Applications in Liquid Systems 257 9 The Use of Ultrasound for the Inactivation of Microorganisms and Enzymes 258 Cristina Arroyo and James G. Lyng
9.1 Introduction 259
9.2 Microbial Inactivation by Ultrasound 259
9.2.1 A Hint of History 259
9.2.2 Mode of Action and Structural Studies 260
9.2.3 Kinetics of Inactivation 264
9.2.4 Factors Affecting the Lethal Effect of Ultrasound 264
9.2.5 Ultrasound in Combination with other Hurdles 272
9.3 Enzyme Inactivation by Ultrasound 272
9.3.1 Alkaline Phosphatase (EC Number
3.1.3.1) 273
9.3.2 Lactoperoxidase (EC Number
1.11.1.7) 274
9.3.3 Lipase (EC number
3.1.1.3) 274
9.3.4 Lipoxygenase (EC Number
1.13.11.12) 275
9.3.5 Pectin Methylesterase (EC Number
3.1.1.11) 275
9.3.6 Peroxidases (EC Number
1.11.1.7) 276
9.3.7 Polyphenol Oxidases (EC Number
1.14.18.1) 277
9.3.8 Proteases 277
9.4 Conclusions and Future Trends 278 References 278 10 Ultrasonic Preparation of Food Emulsions 287 A. Shanmugam and M. Ashokkumar
10.1 Introduction 287
10.2 Formation of Emulsions 288
10.3 Conventional Emulsification Techniques 290
10.4 Ultrasonic Emulsification 292
10.5 Factors Affecting Sonoemulsification 293
10.5.1 Sonication Frequency 293
10.5.2 Sonication Power 294
10.5.3 Solution Temperature 295
10.5.4 Sonication Time 295
10.6 Role of Food Additives during Emulsification 295
10.6.1 Emulsifiers 295
10.6.2 Stabilizers 296
10.7 Case Studies on Ultrasonic Emulsification 297
10.8 Advantages of US over Other Emulsification Techniques 302
10.9 Conclusions 306 References 306 11 Osmotic Dehydration and Blanching: Ul