Food emulsions : principles, practices, and techniques

Food Emulsions Principles, Practices, and Techniques Second Edition......Page 1
Dedication......Page 5
Preface......Page 6
About the Author......Page 8
Contents......Page 9
1.1 Emulsion science in the food industry......Page 17
1.1.2 Development of new analytical techniques to characterize food properties......Page 18
1.2.1 Definitions......Page 19
1.2.2 Mechanisms of emulsion instability......Page 21
1.2.3 Ingredient partitioning in emulsions......Page 22
1.2.5 Complexity of food emulsions......Page 23
1.3.1 Disperse phase volume fraction......Page 24
1.3.2 Particle size distribution......Page 25
1.3.2.1 Presenting particle size data......Page 26
1.3.2.2 Mean and standard deviation......Page 28
1.3.2.3 Mathematical models......Page 31
1.3.4 Droplet charge......Page 33
1.3.5 Droplet crystallinity......Page 34
1.3.6 Droplet interactions......Page 35
1.4 Hierarchy of emulsion properties......Page 36
1.5.1.1 Relevance to industry and society......Page 37
1.5.1.3 Availability of appropriate theory and instrumentation......Page 38
1.5.2.1 Trial-and-error approach......Page 39
1.5.2.3 Physicochemical approach......Page 40
1.5.2.5 Open-minded approach......Page 41
1.6 Overview and philosophy......Page 42
2.1 Introduction......Page 43
2.3.1 Covalent interactions......Page 44
2.3.2 Electrostatic interactions......Page 45
2.3.3.2 Induction force......Page 49
2.3.3.3 Orientation forces......Page 50
2.4 Overall intermolecular pair potential......Page 51
2.5 Molecular structure and organization is determined by a balance of interaction energies and entropy effects......Page 54
2.6 Thermodynamics of mixing......Page 57
2.6.1 Potential energy change on mixing......Page 58
2.6.3 Overall free energy change on mixing......Page 59
2.6.4 Complications......Page 60
2.7 Molecular conformation......Page 61
2.8.1 Hydrogen bonds......Page 63
2.9 Computer modeling of liquid properties......Page 64
2.9.1 Monte Carlo techniques......Page 65
2.10 Measurement of molecular characteristics......Page 66
3.2 Colloidal interactions and droplet aggregation......Page 68
3.3.2 Modeling van der Waals interactions......Page 71
3.3.3.2 Hamaker function......Page 72
3.3.3 General features of van der Waals interactions......Page 77
3.4.2.1 Interdroplet pair potential......Page 78
3.4.2.2 Factors influencing electrical characteristics of surfaces......Page 79
3.4.2.4 Influence of ion bridging on electrostatic interactions......Page 82
3.4.3 General characteristics of electrostatic interactions......Page 83
3.5.2.2 Mixing contribution......Page 84
3.5.2.3 Elastic contribution......Page 86
3.5.2.4 Distance dependence of steric interactions......Page 87
3.5.3 General characteristics of steric interactions......Page 88
3.6.1 Origin of depletion interactions......Page 89
3.6.2 Modeling of depletion interactions......Page 90
3.6.3 General characteristics of depletion interactions......Page 92
3.7.1 Origin of hydrophobic interactions......Page 93
3.7.2 Modeling hydrophobic interactions......Page 94
3.8.2 Modeling hydration interactions......Page 96
3.8.3 General characteristics of hydration interactions......Page 97
3.9.1 Origin of thermal fluctuation interactions......Page 98
3.9.3 General characteristics of fluctuation interactions......Page 99
3.10.2 Hydrodynamic flow of continuous phase......Page 100
3.11 Total interaction potential......Page 101
3.11.1 van der Waals and steric......Page 102
3.11.2 van der Waals, steric, and electrostatic......Page 103
3.11.4 van der Waals, steric, electrostatic, and depletion......Page 106
3.12 Measurement of colloidal interactions......Page 107
3.13 Prediction of colloidal interactions in food emulsions......Page 108
4.1 Introduction......Page 109
4.2 Fats and oils......Page 110
4.2.2 Bulk physicochemical properties......Page 112
4.2.3 Fat crystallization......Page 114
4.2.3.1 Supercooling......Page 115
4.2.3.2 Nucleation......Page 116
4.2.3.3 Crystal growth......Page 119
4.2.3.5 Polymorphism......Page 120
4.2.3.6 Crystallization of edible fats and oils......Page 121
4.2.3.7 Fat crystallization in emulsions......Page 122
4.2.4 Chemical changes......Page 123
4.2.5.3 Crystallization behavior......Page 124
4.2.5.6 Oil quality......Page 125
4.3.1 Molecular structure and organization......Page 126
4.3.2 Bulk physicochemical properties......Page 127
4.3.3.1 Interaction of water with ionic solutes......Page 128
4.3.3.2 Interaction of water with polar solutes......Page 131
4.3.3.3 Interaction of water with nonpolar solutes: the hydrophobic effect......Page 132
4.3.5 Selection of an appropriate aqueous phase......Page 135
4.4.1.1 Molecular characteristics......Page 136
4.4.1.2 Physicochemical properties......Page 138
4.4.1.3.1......Page 144
4.4.1.3.2......Page 145
4.4.1.3.3......Page 147
4.4.1.3.4......Page 148
4.4.1.4 Common food-grade surfactants......Page 149
4.4.1.4.3......Page 150
4.4.2.1 Molecular characteristics......Page 151
4.4.2.2 Interfacial activity and emulsion stabilization......Page 152
4.4.2.3 Common biopolymer food emulsifiers......Page 154
4.4.3 Selection of an appropriate emulsifier......Page 160
4.5.1 Thickening agents......Page 162
4.5.1.2 Relationship between biopolymer molecular structure and effective volume in solution......Page 163
4.5.1.3 Viscosity enhancement by biopolymers in solution......Page 164
4.5.1.4 Shear thinning in biopolymer solutions......Page 166
4.5.2 Gelling Agents......Page 167
4.5.3.1.1......Page 172
4.5.3.1.3......Page 173
4.5.3.1.4......Page 174
4.5.3.1.7......Page 175
4.5.3.1.8......Page 176
4.5.3.1.10......Page 177
4.5.3.2.1......Page 178
4.5.3.3 Biopolymer blends......Page 179
4.5.4 Selection of an appropriate texture modifier......Page 181
4.6.2 Minerals......Page 182
4.6.4 Antioxidants......Page 183
4.6.6 Flavors......Page 185
4.6.8 Weighting agents......Page 186
4.7 Factors influencing ingredient selection......Page 187
5.1 Introduction......Page 189
5.2.1 Interfaces separating two pure liquids......Page 190
5.2.2 Interfaces in the presence of solutes......Page 193
5.3.1.1 GasÒliquid interface in the absence of solutes......Page 196
5.3.1.2 GasÒliquid interface in the presence of solutes......Page 197
5.3.2 Relationship between adsorbed and bulk solute concentrations......Page 198
5.3.4 Adsorption kinetics......Page 201
5.3.4.1 Movement of molecules to the vicinity of an interface......Page 202
5.3.4.2 Attachment of emulsifier molecules to interface......Page 204
5.4.1 Origin of interfacial charge......Page 205
5.4.2 Ion distribution near a charged interface......Page 207
5.4.3 Factors influencing interfacial electrical properties of emulsions......Page 212
5.5.1 Factors influencing interfacial composition......Page 213
5.5.2 Characterization of interfacial composition in emulsions......Page 216
5.6.1 Factors influencing interfacial structure......Page 218
5.6.2 Characterization of interfacial structure in emulsions......Page 222
5.6.2.2 Spectroscopy techniques......Page 223
5.6.2.3 Interference reflection techniques......Page 224
5.6.2.5 Langmuir trough measurements......Page 225
5.6.2.6 Surface force measurements......Page 226
5.6.2.8 Biochemical techniques......Page 227
5.7.2 Characterization of interfacial tension......Page 228
5.7.2.1 Du Nouy ring method......Page 229
5.7.2.2 Wilhelmy plate method......Page 230
5.7.2.3 Sessile and pendant drop methods......Page 231
5.7.2.4 Drop-volume method......Page 232
5.7.2.5 Spinning drop method......Page 233
5.7.2.6 Maximum bubble pressure method......Page 234
5.8.1 Factors influencing interfacial rheology......Page 235
5.8.2.1 Measurement of interfacial shear rheology......Page 236
5.8.2.2 Measurement of interfacial dilational rheology......Page 237
5.9.1 Properties of curved interfaces......Page 239
5.9.2 Contact angles and wetting......Page 240
5.9.3 Capillary rise and meniscus formation......Page 243
5.9.4 Interfacial phenomenon in food emulsions......Page 244
6.2 Overview of homogenization......Page 246
6.3 Flow profiles in homogenizers......Page 249
6.4.1.1 Interfacial forces......Page 250
6.4.1.2 Disruptive forces......Page 252
6.4.2 Droplet coalescence......Page 259
6.4.3 The role of the emulsifier......Page 261
6.5.1 High-speed mixers......Page 262
6.5.2 Colloid mills......Page 263
6.5.3 High-pressure valve homogenizers......Page 264
6.5.4 Ultrasonic homogenizers......Page 266
6.5.5 Microfluidization......Page 268
6.5.6 Membrane and microchannel homogenizers......Page 269
6.5.7 Homogenization efficiency......Page 270
6.5.8.1 Energy densities and efficiency......Page 272
6.5.8.6 Selecting and purchasing an homogenizer......Page 273
6.6.1 Emulsifier type and concentration......Page 274
6.6.3 Properties of component phases......Page 276
6.6.4 Temperature......Page 277
6.7.1 Nonionic surfactants......Page 278
6.7.3 Biopolymer emulsifiers......Page 279
6.8 Future developments......Page 280
7.1 Introduction......Page 282
7.2.1 Thermodynamic stability......Page 283
7.2.2 Kinetic stability......Page 285
7.3 Gravitational separation......Page 286
7.3.1.1 StokesÌ law......Page 287
7.3.1.2 Deviations from Stokes' law......Page 289
7.3.2.1 Minimize density difference......Page 297
7.3.2.2 Reduce droplet size......Page 298
7.3.3 Experimental characterization of gravitational separation......Page 299
7.4 General features of droplet aggregation......Page 302
7.4.2 Film thinning......Page 303
7.4.4 Film rupture......Page 304
7.5.1.1 Collision frequency......Page 305
7.5.1.2 Collision efficiency......Page 309
7.5.1.3 Overall droplet growth rate......Page 310
7.5.2.1 Collision frequency......Page 311
7.5.3 Structure and properties of flocculated emulsions......Page 318
7.5.3.2 Use of fractal geometry to describe floc structure......Page 319
7.5.3.3 Influence of floc structure on emulsion properties......Page 321
7.5.4 Experimental measurement of flocculation......Page 322
7.6 Coalescence......Page 323
7.6.1.1 Physical and molecular processes associated with coalescence......Page 324
7.6.1.2 Mechanisms of film rupture......Page 326
7.6.1.3 Hole formation......Page 328
7.6.1.4 Rate-limiting step for coalescence......Page 329
7.6.1.5 Modeling droplet growth due to coalescence......Page 331
7.6.2.2 Prevention of rupture of interfacial membranes......Page 332
7.6.3.1 Emulsifier type......Page 333
7.6.3.2 Influence of environmental conditions......Page 334
7.6.4 Measurement of droplet coalescence......Page 335
7.7 Partial coalescence......Page 337
7.7.1 Physical basis of partial coalescence......Page 338
7.7.2.1 Prevention of close contact......Page 340
7.7.2.3 Control of crystal concentration, structure, and location......Page 341
7.7.3 Experimental characterization of partial coalescence......Page 342
7.8 Ostwald ripening......Page 343
7.8.1 Physical basis of Ostwald ripening......Page 344
7.8.2.3 Interfacial membrane......Page 346
7.8.2.4 Droplet composition......Page 347
7.9 Phase inversion......Page 348
7.9.1.1 Surfactant-induced phase inversion......Page 349
7.9.2.2 Emulsifier type and concentration......Page 350
7.9.3 Characterization of phase inversion......Page 351
7.10 Chemical and biochemical stability......Page 352
8.1 Introduction......Page 353
8.2.1.1 Ideal elastic solids......Page 354
8.2.1.2 Nonideal elastic solids......Page 356
8.2.2.1 Ideal liquids......Page 357
8.2.2.2 Nonideal liquids......Page 358
8.2.3 Plastics......Page 363
8.2.3.2 Nonideal plastics......Page 364
8.2.4.1 Transient tests......Page 365
8.2.4.2 Dynamic tests......Page 366
8.3 Measurement of rheological properties......Page 368
8.3.1 Simple compression and elongation......Page 369
8.3.2.1 Capillary viscometers......Page 372
8.3.2.2 Mechanical viscometers and dynamic rheometers......Page 373
8.3.2.3.3......Page 375
8.3.3 Empirical techniques......Page 376
8.4 Rheological properties of emulsions......Page 377
8.4.1 Dilute suspensions of rigid spherical particles......Page 378
8.4.2 Dilute suspensions of fluid spherical particles......Page 379
8.4.3 Dilute suspensions of rigid nonspherical particles......Page 380
8.4.4 Dilute suspensions of flocculated particles......Page 382
8.4.5 Concentrated suspensions of nonflocculated particles in the absence of long- range colloidal interactions......Page 384
8.4.6 Suspensions of nonflocculated particles with repulsive interactions......Page 386
8.4.7 Concentrated suspensions with attractive interactions: flocculated systems......Page 388
8.4.8 Emulsions with semisolid continuous phases......Page 392
8.5 Computer simulation of emulsion rheology......Page 393
8.6.1 Disperse phase volume fraction......Page 394
8.6.2 Rheology of component phases......Page 395
8.6.4 Colloidal interactions......Page 396
8.6.5 Droplet charge......Page 397
8.7 Future Trends......Page 398
9.1.1 Physicochemical processes......Page 400
9.1.4 General aspects......Page 401
9.2.1 Partitioning between a homogeneous liquid and a vapor......Page 402
9.2.2 Influence of flavor ionization......Page 405
9.2.3 Influence of flavor binding on partitioning......Page 406
9.2.5 Partitioning in emulsions in the absence of an interfacial membrane......Page 408
9.2.6 Partitioning in emulsions in the presence of an interfacial membrane......Page 410
9.2.6.1 Reversible binding......Page 411
9.3.1 Overview of physicochemical process of flavor release......Page 412
9.3.2 Release of nonvolatile compounds taste......Page 413
9.3.2.2 Kinetics of flavor release......Page 414
9.3.3.1 Flavor release from homogeneous liquids......Page 418
9.3.3.2 Influence of ingredient interactions......Page 421
9.3.3.3 Flavor release from emulsions......Page 423
9.4 Emulsion mouthfeel......Page 426
9.5.1.1 Equilibrium measurements......Page 428
headspace analysis......Page 429
9.5.2.1 Equilibrium measurements......Page 430
analysis......Page 431
9.5.3 Sensory analysis......Page 432
9.6.1 Disperse phase volume fraction......Page 433
9.6.2 Droplet size......Page 435
9.6.3 Interfacial characteristics......Page 437
9.6.4 Oil phase characteristics......Page 438
9.6.5 Aqueous phase characteristics......Page 439
9.7 Concluding remarks and future directions......Page 440
10.1 Introduction......Page 442
10.2.1.1 Transmission, reflection, and refraction......Page 443
10.2.1.2 Light absorption......Page 444
10.2.1.3 Light scattering......Page 446
10.2.3 Quantitative description of appearance......Page 449
10.3 Mathematical modeling of emulsion color......Page 450
10.3.1 Calculation of scattering characteristics of emulsion droplets......Page 451
10.3.2.1 Dilute emulsions......Page 453
10.3.2.2 Concentrated emulsions......Page 454
10.3.3 Relationship of tristimulus coordinates to spectral reflectance and transmittance......Page 456
10.3.5 Numerical calculations of emulsion color......Page 457
10.3.6 Influence of measurement cell......Page 460
10.4 Measurement of emulsion color......Page 461
10.4.1.1 Transmission spectrophotometry......Page 462
10.4.1.2 Reflection spectrophotometry......Page 463
10.4.2 Trichromatic colorimeters......Page 464
10.5 Major factors influencing emulsion color......Page 465
10.5.1 Droplet concentration and size......Page 466
10.5.3 Colorant type and concentration......Page 467
10.6 Concluding remarks and future directions......Page 469
11.2 Testing emulsifier effectiveness......Page 471
11.2.1 Emulsifying capacity......Page 472
11.2.2 Emulsion stability index......Page 473
11.3.1.1 Conventional optical microscopy......Page 475
11.3.1.2 Laser scanning confocal microscopy......Page 478
11.3.1.3 Electron microscopy......Page 480
11.3.1.4 Atomic force microscopy......Page 483
11.3.2.1 Principles......Page 485
11.3.2.2 Measurement techniques......Page 487
11.3.2.3 Applications......Page 490
11.3.3.2 Measurement techniques......Page 491
11.3.4 Electrical pulse counting......Page 495
11.3.5.2 Measurement techniques......Page 497
11.3.6.1 Principles......Page 498
11.3.6.2 Measurement techniques......Page 500
11.3.7 Nuclear magnetic resonance......Page 502
11.3.8 Neutron scattering......Page 503
11.4.1 Proximate analysis......Page 505
11.4.2.1 Principles......Page 506
11.4.2.2 Measurement Techniques......Page 507
11.4.3.1 Principles......Page 508
11.5.1.1 Principles......Page 509
11.5.1.3 Applications......Page 510
11.5.2.2 Measurement techniques......Page 511
11.5.2.3 Applications......Page 513
11.5.3.2 Measurement techniques......Page 514
11.5.3.3 Applications......Page 515
11.5.4.1 Principles......Page 516
11.5.4.3 Applications......Page 517
11.6.1 Particle electrophoresis......Page 518
11.6.2 Electroacoustics......Page 520
11.7 Droplet interactions......Page 522
12.2.1.1 Dispersed phase......Page 524
12.2.1.2 Interfacial membrane......Page 525
12.2.2 Microstructure......Page 527
12.2.3 Production......Page 528
12.2.4.1 Stability......Page 529
12.2.4.4 Flavor......Page 530
12.2.5.2 Butter......Page 531
12.2.5.3 Ice cream......Page 532
12.2.5.4 Yogurt......Page 533
12.2.5.5 Cheese......Page 534
12.3.1.1 Dispersed phase......Page 535
12.3.1.2 Interfacial membrane......Page 537
12.3.2 Microstructure......Page 538
12.3.4.1 Stability......Page 539
12.3.4.3 Flavor......Page 541
12.4 Dressings......Page 542
12.4.1.1 Dispersed phase......Page 543
12.4.1.3 Interfacial membrane......Page 545
12.4.2 Microstructure......Page 546
12.4.4.1 Stability......Page 548
12.4.4.2 Rheology......Page 550
12.4.4.4 Flavor......Page 551
References......Page 553