Food Structure (eBook)

Front Cover 1
Food Structure—its Creation and Evaluation 4
Copyright Page 5
Table of Contents 8
PREFACE 6
ACKNOWLEDGEMENTS 7
CHAPTER 1. THE RELEVANCE OF FOOD STRUCTURE–A DENTAL CLINICAL PERSPECTIVE 12
References 16
CHAPTER 2. MIXED AND FILLED GELS—MODELS FOR FOODS 18
Introduction 18
Single component gels 18
Two component mixed gels 19
Filled gels 26
Sensory properties 28
References 29
CHAPTER 3. GEL STRUCTURE OF FOOD BIOPOLYMERS 36
Introduction 36
Protein gels 37
Globular proteins 43
Polysaccharides 45
Complex food systems 48
Acknowledgements 50
References 50
CHAPTER 4. THE STRUCTURE AND STABILITY OF EMULSIONS 52
Introduction 52
Stability 54
Structure 56
Creaming 59
Flocculation and coalescence 65
References 67
CHAPTER 5. STRUCTURE AND PROPERTIES OF LIQUID AND SOLID FOAMS 70
Introduction 70
Classification of foamed structures 70
Elastic properties of solid foams 73
Strength properties of solid foams 80
Liquid-filled foams 82
Conclusions 84
References 84
CHAPTER 6. THE POLYMER / WATER RELATIONSHIP—ITS IMPORTANCE FOR FOOD STRUCTURE 86
Introduction 86
Definitions 86
High water content systems e.g. protein and polysaccharide gels and dispersions (aw> 0.9–1.00)
Intermediate/low moisture content systems (aw < 0.9)
Acknowledgements 101
References 102
CHAPTER 7. POLYMER FRACTURE 104
Introduction 104
Molecular aspects of fracture 106
Fracture mechanics 109
Plastic zones and crazes 113
Fracture of glassy thermoplastics—PMMA 115
Environmental effects 118
Impact 119
Toughness and toughening of polymers 122
Conclusion 123
References 123
CHAPTER 8. STRUCTURAL STABILITY OF INTERMEDIATE MOISTURE FOODS—A NEW UNDERSTANDING? 126
Introduction 126
Theoretical background 128
Structural stability of intermediate moisture (IM) foods 140
Conclusion 152
Acknowledgements 153
References 153
CHAPTER 9. 'COLLAPSE' PHENOMENA—A UNIFYING CONCEPT FOR INTERPRETING THE BEHAVIOUR OF LOW MOISTURE FOODS 160
Introduction 160
Materials and methods 162
Results 165
Discussion 172
Acknowledgements 186
References 187
CHAPTER 10. CREATION OF FIBROUS STRUCTURES BY SPINNERETLESS SPINNING 192
Introduction 192
Preparation of two-phase dopes 194
Structure and properties of two-phase dopes 195
Mechanical and other physicochemical properties of fibrousmaterials 198
Versions of the spinneretless spinning process 201
Spinneretless spinning as an element of food production technology 204
References 205
CHAPTER 11. DRY SPINNING OF MILK PROTEINS 208
Introduction 208
Proteins, their functionality and traditional texturization processes 209
Protein texturization by wet spinning and extrusion cooking 215
Dry spinning of milk proteins 219
Evaluation of results 227
Acknowledgements 228
References 228
CHAPTER 12.PROTEIN EXTRUSION—MORE QUESTIONS THAN ANSWERS? 230
Is denaturation necessary? 231
What is the nature of the 'melt' phase? 232
Do the proteins align in the shear field? 233
How important are charge effects? 235
What bonds stabilize the aggregate and when do they form? 237
Is the changing chemical composition of the 'melt' of importance? 238
Discussion 239
References 239
CHAPTER 13. REFORMED MEAT PRODUCTS—FUNDAMENTAL CONCEPTS AND NEW DEVELOPMENTS 242
Introduction 242
Muscle structure 243
Mechanical properties of meat 245
Adhesion between meat pieces: principles 247
Factors affecting the extraction of protein from meat 250
The adhesive properties of muscle protein gels 255
Adhesion in the absence of sodium chloride, and adhesive properties of non-meat gels 257
Current manufacturing practice: key aspects 258
The success of meat reforming operations 268
References 268
CHAPTER 14. SURIMI-BASED FOODS—THE GENERAL STORY AND THE NORWEGIAN APPROACH 276
Introduction 276
What is surimi? 276
Structure formation in surimi and surimi-based foods 278
Recent Norwegian work on surimi 285
References 287
CHAPTER 15. STRUCTURED FAT SYSTEMS 290
Introduction 290
The structure and crystallization of triglycerides 291
Lard and vegetable shortenings 298
Chocolate 301
Caramels and fudges 303
Ice cream and dessert toppings 304
Acknowledgements 305
References 305
CHAPTER 16. STRUCTURED SUGAR SYSTEMS 308
Introduction 308
Available sugars 309
Physical characteristics 310
Sugar confectionery 314
Non-sucrose sweeteners in confectionery products 317
Baked products 318
Conclusions 321
References 321
CHAPTER 17. ELEMENTS OF CEREAL PRODUCT STRUCTURE 324
Introduction 324
Molecular structure and properties of the major components of baked systems 325
Development of structure in the baking process 330
Time-dependent changes occurring post-baking 336
References 339
CHAPTER 18. EXTRUSION AND CO-EXTRUSION OF CEREALS 342
Introduction 342
Manufacture of products by direct expansion at the die 343
'Half products' or 'pellets' 358
Co-extrusion processes 358
Acknowledgements 359
References 359
CHAPTER 19. THE EVALUATION OF FOOD STRUCTURE BY LIGHT MICROSCOPY 362
Introduction 362
Use of the stereomicroscope 362
Use of the compound light microscope 364
Specimen preparation 364
Physical methods of obtaining contrast 365
Interference microscopy 366
Chemical methods of obtaining contrast 368
The combination of physical and chemical methods of obtaining contrast 370
Staining and interterence microscopy (Figure 19.9) 372
Estimation and measuring size with the optical microscope 372
Conclusions 373
Acknowledgement 375
References 375
CHAPTER 20. AN ELECTRON MICROSCOPIST'S VIEW OF FOODS 378
Introduction 378
Plant tissues 379
Meat 381
Foams and emulsions 386
Chocolate 389
Gel systems 393
Conclusions 396
Acknowledgment 396
CHAPTER 21. SMALL DEFORMATION MEASUREMENTS 398
Introduction 398
Small deformation measurements 398
Constitutive equations and time–temperature superposition 401
Mechanical spectra for model systems 402
Strain dependence 405
Application of small deformation measurements to food precursors 406
Conclusion 410
References 411
CHAPTER 22. BEHAVIOUR OF FOODS IN LARGE DEFORMATION 412
Introduction 412
Stress, strain and the stored energy function 413
Large deformation behaviour of viscoelastic doughs 414
Comparison of viscosities in shear and in elongational flow 416
Compressional experiments 419
Elasticity of foods and normal stresses at large deformations 420
Fracture 422
References 424
CHAPTER 23. THE SENSORY-RHEOLOGICAL INTERFACE 428
Introduction 428
The three phases of texture evaluation during mastication 429
Sensory evaluation of fluid food viscosity and its instrumental simulation 429
Sensory evaluation of firmness and its instrumental simulation 434
Conclusions 440
References 441
CHAPTER 24. EVALUATION OF CRISPNESS 444
Introduction 444
Early sensory studies of crispness 445
An auditory hypothesis of crispness 445
Testing the hypothesis that crispness is a sound 449
Acoustical stimuli and sensations 454
Non-auditory sensations that affect crispness 456
Combination studies 456
Conclusion 458
References 458
CHAPTER 25. BEYOND THE TEXTURE PROFILE 460
Introduction 460
Definition of texture 460
Sensory evaluation 461
The texture profile 462
Classification of terms 462
Reference scales 463
Intensity rating 465
Conclusion 471
References 471
CHAPTER 26. ORAL PERCEPTION OF TEXTURE 476
Introduction 476
Phases of oral processing 476
Sources of sensation 477
Muscle activity 480
Forces 483
Food breakdown in the mouth 484
Jaw movement 485
Swallowing 488
Conclusions 489
Acknowledgements 489
References 489
LIST OF PARTICIPANTS 494
INDEX 500