Food Mixing: Principles and Applications

Cover......Page 1
Contents......Page 5
Contributors......Page 11
1.2 Design criteria for mixing......Page 13
1.3.1 Quality assurance compliance through mixing......Page 14
1.3.2 Engineering texture through mixing......Page 15
1.5 Book objectives......Page 16
2.1 Introduction......Page 18
2.2 Defining mixing......Page 19
2.2.2 Mesomixing......Page 21
2.3 Scale of scrutiny......Page 22
2.4 Quantifying mixedness......Page 23
2.4.1 Inference of mixing indices......Page 25
2.5 Determining the end point of mixing......Page 26
2.5.1 Solids mixing......Page 27
2.5.2 Fluid mixing......Page 28
2.5.4 Alternative measures of mixedness in industrial practice......Page 30
2.6.1 Modelling of residence time distributions......Page 31
3.2 Fluid mixing......Page 33
3.2.1 Kinematics of fluid flow......Page 34
3.2.2 Quantification of flow regimes......Page 36
3.2.3 Chaotic advection......Page 44
3.2.4 Fluid mixing mechanisms......Page 47
3.3.1 Mixing flow in solids......Page 52
3.3.2 Solids mixing mechanism......Page 53
3.4.2 Fluids......Page 54
4.1 Introduction......Page 62
4.2.1 Forces acting on dispersed particles......Page 63
4.2.2 Parameters affecting suspension rheology......Page 64
4.3.1 Shear flow......Page 66
4.3.2 Elongational flow......Page 71
4.4 Effects of mixing on fluid rheology......Page 73
4.5.1 Theory......Page 75
4.5.2 Mixer rheometry applications......Page 78
4.6 Conclusion......Page 80
5.2.1 Portable mixers......Page 85
5.2.2 General purpose liquid mixers......Page 87
5.2.3 Mixer shafts design......Page 88
5.2.5 Special purpose liquid mixing equipment......Page 91
5.2.6 Food specific mixing equipment......Page 94
5.3.1 Ribbon blenders......Page 95
5.3.3 Combination blenders......Page 96
5.3.5 Loading and emptying blenders......Page 98
5.4 Equipment components......Page 99
5.4.3 Seals......Page 100
6.2.1 Dimensional analysis......Page 102
6.2.2 Scale-up with geometric similarity......Page 106
6.2.3 Scale-up without geometric similarity......Page 112
6.3 Scale-up for powder mixing......Page 116
7.1 Introduction......Page 119
7.2 Torque and power measurement......Page 120
7.3.1 Hot-wire anemometry......Page 122
7.3.2 Laser Doppler anemometry......Page 123
7.3.4 Flow visualization using computer vision......Page 125
7.3.5 Particle image velocimetry......Page 127
7.3.6 Planar laser-induced fluorescence......Page 128
7.4 Quantification of mixing time......Page 130
7.4.1 NIR spectroscopy......Page 131
7.4.2 Chemical imaging......Page 132
8.1.2 Steps towards CFD simulation of mixing processes......Page 137
8.2 Conservation equations......Page 142
8.2.1 Mass conservation......Page 143
8.2.2 Momentum conservation......Page 144
8.2.3 Turbulence......Page 146
8.2.5 Species transport......Page 150
8.2.7 Boundary conditions......Page 151
8.3.2 Grid generation......Page 154
8.3.3 Discretisation......Page 155
8.3.4 Finite-volume discretisation methods......Page 156
8.3.5 Solver methods......Page 157
8.4.2 Representation of the impeller......Page 159
8.4.3 Prediction of mixer performance characteristics......Page 163
8.4.4 Simulation of unbaffled or partially baffled stirred tanks......Page 165
8.4.5 Simulation of single-phase flow in baffled stirred tanks......Page 167
8.4.6 Mixing and blending simulations......Page 169
8.4.7 Multi-phase simulations......Page 171
8.5.1 Challenges for simulation of food processes......Page 175
8.5.2 Examples of food applications......Page 177
8.6 Closing remarks......Page 180
9.1 Introduction......Page 187
9.2.1 Kinetically trapped nano-emulsions......Page 188
9.2.2 Pickering emulsions......Page 189
9.2.3 Double emulsions......Page 192
9.2.4 Air-filled emulsions......Page 197
9.2.5 Water-in-water emulsions......Page 199
9.3.2 Improved emulsification processes......Page 205
9.3.4 Reduced use of surfactants for environmental reasons......Page 206
10.1 Introduction......Page 211
10.2.2 State of complete particle motion......Page 212
10.2.4 State of homogeneous or uniform suspension......Page 213
10.3.1 Influence of physical properties......Page 217
10.3.3 Influence of geometric parameters......Page 218
10.4 Hydrodynamics of particle suspension and distribution......Page 221
10.4.2 Particle settling and drag......Page 222
10.5 Scale-up of solid–liquid mixing......Page 229
10.6 Damage to food particles in suspension......Page 232
10.7 Fine particle slurries......Page 235
11.2.1 Characteristics of dispersed phase—mean diameter......Page 242
11.2.2 Gas dispersion—bubble behaviour......Page 243
11.2.3 Gas dispersion in agitated vessels......Page 244
11.3 Power input to turbine dispersers......Page 246
11.6.1 Mixing by mechanical agitation under positive pressure......Page 247
11.6.3 Steam-induced mixing......Page 248
11.7.1 Gas hold-up......Page 250
11.7.2 Bubble size distribution......Page 253
11.7.3 Rheological characterization......Page 255
11.8 Role of gases and specific ingredients in characterizing interfacial and rheological properties......Page 258
11.9 Stability of foams and solidification of bubbly dispersions......Page 259
11.10 Ultrasound in gas mixing and applications in food aeration......Page 261
12.1. Introduction......Page 265
12.2.1 Efficiency of stretching......Page 266
12.2.2 Dispersive mixing efficiency......Page 267
12.2.3 Distributive mixing efficiency......Page 268
12.3. Governing equations for calculation of flow......Page 269
12.4.2 Techniques to handle moving parts......Page 270
12.5.2. Analysis of mixing in 2D single-screw and twin-screw geometries......Page 271
12.6. 3D Numerical simulation of twin-screw continuous mixer geometries......Page 272
12.6.1 Distributive mixing efficiency in a 3D mixing geometry......Page 273
12.6.2 Evaluation of dispersive mixing in 3D continuous mixer geometry......Page 274
12.7. Prediction of bubble and drop dispersion in a continuous mixer......Page 276
12.8. Summary......Page 279
13.2.1 Types of mixtures......Page 281
13.3.1 Sampling......Page 282
13.3.2 Sample variance and standard deviation......Page 284
13.3.5 Estimating the true variance (σ[sup(2)]) from the random sample variance (S[sup(2)])......Page 285
13.3.8 Influence of particle size and powder cohesiveness on mixture quality......Page 287
13.4.2 Diffusion or micromixing......Page 288
13.5.1 Segregation......Page 289
13.5.2 Reducing segregation......Page 291
13.6.2 Convective mixers......Page 292
13.6.5 Continuous mixers......Page 294
13.7.2 Mixer selection......Page 295
13.7.3 Process design......Page 296
13.8.1 Hygiene and cleaning......Page 297
13.8.4 Dust prevention and control......Page 298
E......Page 301
M......Page 302
U......Page 303
Z......Page 304
Colour plates......Page 305