Food Oral Processing: Fundamentals of Eating and Sensory Perception

Preface xiv    Contributors xvii     PART ONE ORAL ANATOMY AND PHYSIOLOGY 1     1 Oral Cavity 3  Luciano Jose Pereira     1.1 Introduction 3     1.2 The oral cavity 3     1.3 Salivary glands and saliva secretion 6     1.4 Orofacial muscles 7     1.5 The tongue 9     1.6 Concluding remarks 12     Acknowledgements 12     References 13     2 Oral Receptors 15  Lina Engelen     2.1 Introduction to oral receptors 15     2.1.1 Babies sense the world around them through the mouth 15     2.1.2 Receptors 15     2.1.3 Innervation and transduction 16     2.2 Taste 17     2.2.1 Taste receptors 18     2.2.2 Taste molecules and modalities 20     2.2.2.1 What substances give rise to the different sensations? 20     2.3 Mechanoreception 22     2.3.1 Tactile stimulation 22     2.3.2 Function during eating 23     2.3.3 Mechanoreceptors in the mouth 24     2.3.3.1 SA1     form and texture 25     2.3.3.2 FA1 25     2.3.3.3 SA2     shape and position of tongue 25     2.3.4 Proprioceptors 26     2.3.4.1 Proprioception 26     2.3.4.2 Muscle spindles 27     2.3.4.3 Golgi tendon organ 27     2.3.4.4 Mechanoreceptors as proprioceptors 28     2.3.5 Periodontal receptors 28     2.3.5.1 Function of periodontal receptors 28     2.3.6 Signal transduction and central processing 29     2.4 Nociception 30     2.4.1 Nociceptors 30     2.4.2 Nociception in food 31     2.4.3 Nociceptive transduction 32     2.5 Thermal perception 33     2.5.1 Thermal sensation 33     2.5.2 Thermoreceptors 34     2.5.3 Thermal transduction 34     2.5.4 Temperature and food 35     2.5.5 The thermoreception and nociception relation 36     2.6 Olfaction 36     2.6.1 Olfaction and food 36     2.6.2 Olfactory receptors and transduction 37     2.7 Concluding remarks 38     References 38     3 Role of Saliva in the Oral Processing of Food 45  Guy Carpenter     3.1 Introduction 45     3.2 Control of salivary secretion 46     3.3 Functionalities of saliva 50     3.3.1 Salivary interactions with the oral mucosa 51     3.3.2 Perception of taste 52     3.3.3 Protection of the oral environment 53     3.4 Saliva in bolus formation, swallowing and oral clearance 54     3.4.1 Bolus formation and swallowing 54     3.4.2 Post-mastication oral clearance 54     3.5 Concluding remarks 56     Acknowledgements 56     References 57     PART TWO FOOD ORAL MANAGEMENT 61     4 Oral Management of Food 63  Andries van der Bilt     4.1 Introduction 63     4.2 Factors infl uencing oral function 63     4.2.1 Dental factors 66     4.2.2 Jaw muscle activity (EMG) and bite force 67     4.2.3 Masticatory performance 68     4.2.4 Swallowing of food 69     4.2.5 Saliva 70     4.3 Influence of food characteristics on chewing 72     4.3.1 Influence of food type on muscle activity, chewing force and jaw movement 74     4.3.2 Crispy food 75     4.3.3 Influence of food type and volume on swallowing 75     4.3.4 Muscle activity and jaw movement in various phases of chewing 78     4.4 Neuromuscular control of chewing and swallowing 79     4.4.1 Cortical masticatory area 80     4.4.2 Central pattern generator 80     4.4.3 Peripheral feedback 80     4.4.4 Simulated chewing experiments 81     4.4.5 Neuromuscular control of chewing crispy food 83     4.5 Concluding remarks 84     References 85     5 Breaking and Mastication of Solid Foods 95  Carolyn F. Ross and Clifford L. Hoye Jr.     5.1 Introduction 95     5.2 Mechanical properties and food texture 96     5.3 Characterisation of mechanical properties 96     5.4 Oral selection of food particles 99     5.4.1 The role of the tongue 99     5.4.2 Selection function 100     5.5 Breakage function 101     5.5.1 Definition of breakage function 101     5.5.2 Crack initiation and propagation 103     5.5.3 Correlations between breakage function and food mechanical properties 105     5.5.4 Limitations of breakage function 107     5.6 Concluding remarks 107     References 108     6 Oral Behaviour of Food Emulsions 111  Anwesha Sarkar and Harjinder Singh     6.1 Introduction 111     6.2 Food emulsions in general 112     6.3 Interfacial layers 113     6.4 Emulsion stability 117     6.4.1 Depletion flocculation 118     6.4.2 Bridging flocculation 119     6.4.3 Coalescence 120     6.5 Behaviour of emulsions under oral conditions 121     6.5.1 Saliva-induced destabilisation 122     6.5.1.1 Neutral or negatively charged emulsion   saliva interactions 124     6.5.1.2 Positively charged emulsion   saliva interactions 125     6.5.2 Shear-induced destabilisation 127     6.5.3 Relating oral destabilisation to sensory perception 129     6.5.3.1 Droplet flocculation 129     6.5.3.2 Droplet coalescence 130     6.6 Concluding remarks 131     References 132     7 Bolus Formation and Swallowing 139  Jianshe Chen     7.1 Introduction 139     7.2 Mechanisms of swallowing 139     7.2.1 Stages of swallowing 139     7.2.1.1 The oral phase 140     7.2.1.2 The pharyngeal phase 141     7.2.1.3 The oesophageal phase 142     7.2.2 Oral pressure and bolus swallowing 143     7.2.2.1 Bolus location before swallowing 143     7.2.2.2 The oral pressure 144     7.2.2.3 Measurements of oral pressure 146     7.3 The formation of a food bolus and the triggering criteria of bolus swallowing 147     7.3.1 Dynamics of bolus formation 147     7.3.2 Critical criteria in triggering a swallow 149     7.3.3 Influences of food properties on bolus formation 152     7.4 Concluding remarks 154     References 155     PART THREE FOOD ORAL PROCESSING AND SENSORY PERCEPTION 157     8 Oral Processing and Texture Perception 159  Lina Engelen and Rene A. de Wijk     8.1 Introduction 159     8.1.1 What is texture? 159     8.1.2 Why is texture important for the perception of foods? 160     8.2 Where is texture sensed in the mouth? 161     8.2.1 The special case of the texture of fat 161     8.3 Texture versus food structure 162     8.3.1 Liquids 162     8.3.2 Semi-solids 162     8.3.3 Solids 163     8.3.3.1 Crispy and crunchy food 163     8.4 The measurement of oral processes 164     8.5 Texture versus oral processing 165     8.6 Texture attributes are systematically related 167     8.7 The role of saliva in texture perception 168     8.7.1 Saliva fl ow rate and texture perception 169     8.7.2 Saliva composition and texture perception 170     8.7.3 Salivary enzymes and texture perception 171     8.8 Oral temperature and texture perception 171     8.9 Concluding remarks 172     References 173     9 Oral Processing and Flavour Sensing Mechanisms 177  Sarah Adams and Andrew J. Taylor     9.1 Introduction 177     9.2 Mechanisms for sensing and measuring taste 178     9.2.1 Taste thresholds 179     9.2.2 Food structure, oral breakdown and tastant release 180     9.3 Mechanisms for sensing and measuring aroma 181     9.4 Mechanisms for sensing and measuring texture 184     9.5 Multi-sensory interactions 187     9.6 Measuring food breakdown and deposition in vivo 189     9.6.1 Imaging food in vivo 190     9.6.2 Spectroscopy of food components in vivo 192     9.6.3 Following mastication in vivo 193     9.7 Biochemical fl avour changes during oral processing 193     9.8 Applications of knowledge to real food products 195     9.9 Concluding remarks 195     Acknowledgements 196     References 196     10 Multi-sensory Integration and the Psychophysics of Flavour Perception 203  Charles Spence     10.1 Introduction 203     10.2 Taste/Gustation 205     10.3 Olfactory   gustatory interactions in multi-sensory flavour perception 206     10.4 Oral   somatosensory contributions to multi-sensory flavour perception 208     10.5 Auditory contributions to multi-sensory flavour perception 210     10.6    Visual flavour   : visual contributions to multi-sensory flavour perception 211     10.7 The cognitive neuroscience of multi-sensory flavour perception 215     10.8 Concluding remarks 216     References 219     PART FOUR PRINCIPLES AND PRACTICES OF INSTRUMENTAL CHARACTERISATION FOR EATING AND SENSORY PERCEPTION STUDIES 225     11    Oral    Rheology 227  Jason R. Stokes     11.1 Introduction to food rheology and oral processing 227     11.2 Liquid food rheology and structure 229     11.2.1 Dispersions of particles and polymers 229     11.2.2 Shear thinning 231     11.2.3 Viscoelasticity 234     11.2.3.1 Linear viscoelasticity 235     11.2.3.2 Non-linear viscoelasticity: normal stresses 236     11.2.3.3 Extensional viscosity 237     11.2.4 Instrumentation for liquid foods 237     11.2.4.1 Cone-and-plate 237     11.2.4.2 Parallel plate 238     11.2.4.3 Concentric cylinder 238     11.2.4.4 Extensional viscosity 238     11.3 Soft food rheology and microstructure 239     11.3.1 Microstructure: gels and glasses 239     11.3.2 Rheology 241     11.3.3 Mechanical properties and fracturing behaviour 244     11.4 Solid food breakdown and rheology 245     11.5 Saliva and rheology 246     11.5.1 Saliva 246     11.5.2 Real or artificial saliva to study food   saliva interactions? 247     11.5.3 Saliva rheology 248     11.6 Sensory perception and the fluid dynamics between tongue and palate 249     11.6.1 Shear flow 250     11.6.2 Shear flow and sensory thickness: what is the shear rate in the mouth? 251     11.6.3 Squeeze flow 253     11.6.4 Shear and squeeze flow: defining an oral shear stress? 255     11.6.5 Micro-rheology: gap dependency, confinement and slip 258     11.7 Concluding remarks 258     References 259     12    Oral    Tribology 265  Jason R. Stokes     12.1 Introduction 265     12.2 Principles of tribology 266     12.2.1 Hydrodynamic lubrication and the Reynolds equation 266     12.2.2 Elastohydrodynamic lubrication 267     12.2.3 Film thickness and friction in isoviscous elastohydrodynamic lubrication 268     12.2.4 Limits of hydrodynamic lubrication: Stribeck curve 270     12.2.5 Boundary lubrication 271     12.3 Food lubrication 273     12.3.1 Kokini models for    smoothness    and    slipperiness    274     12.3.2 Biosubstrates and simulated oral contacts 275     12.3.3 Soft-tribology 277     12.3.3.1 Master curves 277     12.3.3.2 Emulsions 278     12.3.3.3 Hydrocolloids 280     12.3.3.4 Saliva 282     12.4 Concluding remarks 284     Acknowledgements 285     References 285     13 Applications of Electromyography (EMG) Technique for Eating Studies 289  Yadira Gonzalez Espinosa and Jianshe Chen     13.1 Introduction 289     13.2 Principles of electromyography technique 289     13.2.1 Muscle motors and their activation 289     13.2.2 Surface electromyography vs. intra-muscular electromyography 290     13.3.3 Main mastication muscles for surface electromyography studies 292     13.3 EMG experimental design and set-up 293     13.3.1 Electrodes, location and placement 293     13.3.2 Selection criteria of subjects for EMG studies 298     13.3.3 Experimental procedures 299     13.3.3.1 Preparation 299     13.3.3.2 Set-up 300     13.3.3.3 Set-up checking and validation 300     13.3.3.4 Test performance 301     13.4 Data analysis 304     13.4.1 Processing of raw EMG signals 304     13.4.1.1 Rectifi cation 305     13.4.1.2 Integration 305     13.4.1.3 Root mean square (RMS) 305     13.4.2 Masticatory parameters: analysis of chewing sequence and individual chewing cycles 306     13.4.2.1 Analysis of the whole chewing sequence 306     13.4.2.2 Analysis of individual chewing cycles 309     13.5 Case studies 312     13.6 Concluding remarks 314     References 315     14 Soft Machine Mechanics and Oral Texture Perception 319  Micha Peleg and Maria G. Corradini     14.1 Introduction 319     14.2 Sensory terms and vocabulary 321     14.3 Soft machine mechanics 322     14.3.1 The signal generated by stiff and soft machines 322     14.3.2 Mechanical sensitivity of soft machines 325     14.4 The    amplifier    and sensory sensitivity 327     14.5 Adaptation and fatigue 333     14.6 Concluding remarks 334     References 335     PART FIVE APPLICATIONS AND NEW PRODUCT DEVELOPMENTS 337     15 Appreciation of Food Crispness and New Product Development 339  Paula Varela and Susana Fiszman     15.1 Introduction 339     15.2 Appreciation of crispy and crunchy texture 339     15.3 Mechanical and structural features of crispy/crunchy food 340     15.3.1 Wet-crisp food products 340     15.3.2 Dry-crisp food products 341     15.3.3 Crusted or multi-layered food products 342     15.4 Characterisation of crispy/crunchy textures 342     15.4.1 Sensory perception and measurement of crispness/crunchiness 342     15.4.2 Instrumental characterisation of crispness/crunchiness 343     15.4.2.1 Texture measurements 343     15.4.2.2 Acoustics 344     15.4.3 Instrumental characterisation of crispness     structure and microstructure 346     15.5 Infl uence of the product design and formulation, process and storage conditions in the attainment, enhancement and maintenance of the crispy/crunchy character in wet, dry and crusted food products 348     15.5.1 Wet-crisp products 348     15.5.2 Dry and crusted products 350     15.5.2.1 Bread as an example of composite crisp food 350     15.5.2.2 Deep fried products 351     15.6 Concluding remarks 353     References 353     16 Design of Food Structure for Enhanced Oral Experience 357  Adam Burbidge     16.1 Introduction 357     16.2 Biophysics of oral perception 357     16.3 Structural stimuli of mechanoreceptors 363     16.4 Engineering of microstructures in food 370     16.4.1 Freeze drying 373     16.4.2 Puffed cereals 375     16.4.3 Spray dried powders 376     16.4.4 Ice cream production 377     16.5 Acknowledgements 378     References 378     Index 381     A colour plate section falls between pages 190 and 191.