Food process engineering and technology /
Zeki Berk, Professor (Emeritus), Department of Biotechnology and Food Engineering, TECHNION, Israel Institute of Technology, Israel.
- Second edition
- xxix, 690 pages : illustrations ; 24 cm
- Food science and technoloy international series .
- Food science and technology international series. .
Contents Introduction – Food is Life .....................................................................................1 1 Physical properties of food materials .............................................................7 1.1 Introduction ........................................................................................... 7 1.2 Mechanical properties ............................................................................ 8 1.2.1 Defi nitions .................................................................................. 8 1.2.2 Rheological models ..................................................................... 9 1.3 Thermal properties ............................................................................... 10 1.4 Electrical properties .............................................................................. 11 1.5 Structure .............................................................................................. 11 1.6 Water activity ....................................................................................... 13 1.6.1 The importance of water in foods ............................................... 13 1.6.2 Water activity, defi nition and determination ............................... 14 1.6.3 Water activity: prediction ........................................................... 14 1.6.4 Water vapor sorption isotherms ................................................. 16 1.6.5 Water activity: effect on food quality and stability ....................... 19 1.7 Phase transition phenomena in foods .................................................... 19 1.7.1 The glassy state in foods ............................................................ 19 1.7.2 Glass transition temperature ...................................................... 20 2 Fluid fl ow .....................................................................................................27 2.1 Introduction ......................................................................................... 27 2.2 Elements of fl uid dynamics .................................................................... 27 2.2.1 Viscosity .................................................................................... 27 2.2.2 Fluid fl ow regimes ...................................................................... 28 2.2.3 Typical applications of Newtonian laminar fl ow .......................... 30 2.2.3a Laminar fl ow in a cylindrical channel (pipe or tube) ........ 30 2.2.3b Laminar fl uid fl ow on fl at surfaces and channels ............. 33 2.2.3c Laminar fl uid fl ow around immersed particles ................. 34 2.2.3d Fluid fl ow through porous media .................................... 36 2.2.4 Turbulent fl uid fl ow ................................................................... 36 2.2.4a Turbulent Newtonian fl uid fl ow in a cylindrical channel (tube or pipe) ............................................................................ 37 2.2.4b Turbulent fl uid fl ow around immersed particles .............. 39 2.3 Flow properties of fl uids ........................................................................ 40 2.3.1 Types of fl uid fl ow behavior ........................................................ 40 2.3.2 Non-Newtonian fl uid fl ow in pipes ............................................. 41 2.4 Transportation of fl uids ........................................................................ 43 2.4.1 Energy relations, the Bernoulli Equation ..................................... 43 2.4.2 Pumps: Types and operation ...................................................... 46 2.4.3 Pump selection .......................................................................... 52 2.4.4 Ejectors ..................................................................................... 55 2.4.5 Piping ....................................................................................... 56 2.5 Flow of particulate solids (powder fl ow) ................................................ 56 2.5.1 Introduction .............................................................................. 56 2.5.2 Flow properties of particulate solids ........................................... 57 2.5.3 Fluidization ............................................................................... 62 2.5.4 Pneumatic transport .................................................................. 65 3 Heat and mass transfer, basic principles .......................................................69 3.1 Introduction ......................................................................................... 69 3.2 Basic relations in transport phenomena ................................................. 69 3.2.1 Basic laws of transport .............................................................. 69 3.2.2 Mechanisms of heat and mass transfer ....................................... 70 3.3 Conductive heat and mass transfer ........................................................ 70 3.3.1 The Fourier and Fick laws ........................................................... 70 3.3.2 Integration of Fourier’s and Fick’s laws for steady-state conductive transport ............................................ 71 3.3.3 Thermal conductivity, thermal diffusivity and molecular diffusivity ............................................................ 73 3.3.4 Examples of steady-state conductive heat and mass transfer processes .............................................................. 76 3.4 Convective heat and mass transfer ......................................................... 81 3.4.1 Film (or surface) heat and mass transfer coeffi cients ................... 81 3.4.2 Empirical correlations for convection heat and mass transfer ..................................................................................... 84 3.4.3 Steady-state interphase mass transfer ......................................... 87 3.5 Unsteady state heat and mass transfer ................................................... 89 3.5.1 The 2 nd Fourier and Fick laws .................................................... 89 3.5.2 Solution of Fourier’s second law equation for an infi nite slab ............................................................................... 90 3.5.3 Transient conduction transfer in fi nite solids ............................... 92 3.5.4 Transient convective transfer in a semi-infi nite body .................... 94 3.5.5 Unsteady state convective transfer .............................................. 95 3.6 Heat transfer by radiation ..................................................................... 96 3.6.1 Interaction between matter and thermal radiation 96 3.6.2 Radiation heat exchange between surfaces .................................. 97 3.6.3 Radiation combined with convection ........................................ 100 3.7 Heat exchangers ................................................................................. 100 3.7.1 Overall coeffi cient of heat transfer ............................................ 100 3.7.2 Heat exchange between fl owing fl uids ....................................... 102 3.7.3 Fouling ................................................................................... 104 3.7.4 Heat exchangers in the food process industry ............................ 105 3.8 Microwave heating .............................................................................. 107 3.8.1 Basic principles of microwave heating ....................................... 108 vi Contents 3.9 Ohmic heating .................................................................................... 109 3.9.1 Introduction ............................................................................ 109 3.9.2 Basic principles ........................................................................ 110 3.9.3 Applications and equipment .................................................... 112 4 Reaction kinetics ........................................................................................115 4.1 Introduction ....................................................................................... 115 4.2 Basic concepts .................................................................................... 116 4.2.1 Elementary and non-elementary reactions ................................. 116 4.2.2 Reaction order ........................................................................ 116 4.2.3 Effect of temperature on reaction kinetics ................................. 119 4.3 Kinetics of biological processes ............................................................ 121 4.3.1 Enzyme-catalyzed reactions ...................................................... 121 4.3.2 Growth of microorganisms ...................................................... 122 4.4 Residence time and residence time distribution .................................... 123 4.4.1 Reactors in food processing ..................................................... 123 4.4.2 Residence time distribution ...................................................... 124 5 Elements of process control .......................................................................129 5.1 Introduction ....................................................................................... 129 5.2 Basic concepts .................................................................................... 129 5.3 Basic control structures ....................................................................... 131 5.3.1 Feedback control ..................................................................... 131 5.3.2 Feed-forward control ............................................................... 131 5.3.3 Comparative merits of control strategies ................................... 132 5.4 The block diagram .............................................................................. 132 5.5 Input, output and process dynamics .................................................... 133 5.5.1 First order response ................................................................. 133 5.5.2 Second order systems .............................................................. 135 5.6 Control modes (control algorithms) .................................................... 136 5.6.1 On-off (binary) control ............................................................ 136 5.6.2 Proportional (P) control .......................................................... 138 5.6.3 Integral (I) control ................................................................... 139 5.6.4 Proportional-integral (PI) control ............................................. 140 5.6.5 Proportional-integral-differential (PID) control ......................... 140 5.6.6 Optimization of control ........................................................... 141 5.7 The physical elements of the control system ......................................... 142 5.7.1 The sensors (measuring elements) ............................................ 142 5.7.2 The controllers ........................................................................ 149 5.7.3 The actuators .......................................................................... 149 6 Size reduction ............................................................................................153 6.1 Introduction ....................................................................................... 153 6.2 Particle size and particle size distribution ............................................. 154 6.2.1 Defi ning the size of a single particle .......................................... 154 6.2.2 Particle size distribution in a population of particles; defi ning a ‘ mean particle size ’ ................................................... 155 6.2.3 Mathematical models of PSD ................................................... 158 6.2.4 A note on particle shape .......................................................... 160 Contents vii 6.3 Size reduction of solids, basic principles ............................................... 163 6.3.1 Mechanism of size reduction in solids ....................................... 163 6.3.2 Particle size distribution after size reduction .............................. 163 6.3.3 Energy consumption ................................................................ 163 6.4 Size reduction of solids, equipment and methods ................................. 165 6.4.1 Impact mills ............................................................................ 166 6.4.2 Pressure mills .......................................................................... 167 6.4.3 Attrition mills .......................................................................... 168 6.4.4 Cutters and choppers .............................................................. 170 7 Mixing .......................................................................................................175 7.1 Introduction ....................................................................................... 175 7.2 Mixing of fl uids (blending) .................................................................. 175 7.2.1 Types of blenders ..................................................................... 175 7.2.2 Flow patterns in fl uid mixing .................................................... 177 7.2.3 Energy input in fl uid mixing ...................................................... 178 7.3 Kneading ............................................................................................ 181 7.4 In-fl ow mixing ..................................................................................... 184 7.5 Mixing of particulate solids ................................................................. 184 7.5.1 Mixing and segregation ............................................................ 184 7.5.2 Quality of mixing, the concept of ‘ mixedness’ ............................ 184 7.5.3 Equipment for mixing particulate solids .................................... 187 7.6 Homogenization ................................................................................. 189 7.6.1 Basic principles ........................................................................ 189 7.6.2 Homogenizers ......................................................................... 191 8 Filtration ...................................................................................................195 8.1 Introduction ....................................................................................... 195 8.2 Depth fi ltration .................................................................................. 196 8.3 Surface (barrier) fi ltration ................................................................... 198 8.3.1 Mechanisms ............................................................................ 198 8.3.2 Rate of fi ltration ...................................................................... 199 8.3.3 Optimization of the fi ltration cycle ........................................... 204 8.3.4 Characteristics of fi ltration cakes .............................................. 205 8.3.5 The role of cakes in fi ltration .................................................... 206 8.4 Filtration equipment ........................................................................... 207 8.4.1 Depth fi lters ............................................................................ 207 8.4.2 Barrier (surface) fi lters ............................................................. 207 8.5 Expression .......................................................................................... 211 8.5.1 Introduction ............................................................................ 211 8.5.2 Mechanisms ............................................................................ 211 8.5.3 Applications and equipment .................................................... 213 9 Centrifugation ...........................................................................................217 9.1 Introduction ....................................................................................... 217 9.2 Basic principles ................................................................................... 218 9.2.1 The continuous settling tank .................................................... 218 9.2.2 From the settling tank to the tubular centrifuge ......................... 220 9.2.3 The baffl ed settling tank and the disc-bowl centrifuge ............... 223 9.2.4 Liquid–liquid separation .......................................................... 224 viii Contents 9.3 Centrifuges ......................................................................................... 226 9.3.1 Tubular centrifuges .................................................................. 227 9.3.2 Disc-bowl centrifuges ............................................................... 228 9.3.3 Decanter centrifuges ................................................................ 230 9.3.4 Basket centrifuges .................................................................... 230 9.4 Cyclones ............................................................................................. 231 10 Membrane processes .................................................................................233 10.1 Introduction ................................................................................... 233 10.2 Tangential fi ltration ........................................................................ 234 10.3 Mass transfer through MF and UF membranes ................................. 235 10.3.1 Solvent transport ............................................................... 235 10.3.2 Solute transport; sieving coeffi cient and rejection ................ 237 10.3.3 Concentration polarization and gel polarization .................. 238 10.4 Mass transfer in reverse osmosis ...................................................... 241 10.4.1 Basic concepts ................................................................... 241 10.4.2 Solvent transport in reverse osmosis .................................... 242 10.5 Membrane systems ......................................................................... 245 10.5.1 Membrane materials .......................................................... 245 10.5.2 Membrane confi gurations .................................................. 247 10.6 Membrane processes in the food industry ........................................ 249 10.6.1 Microfi ltration ................................................................... 249 10.6.2 Ultrafi ltration ..................................................................... 249 10.6.3 Nanofi ltration and reverse osmosis ..................................... 251 10.7 Electrodialysis ................................................................................. 253 11 Extraction ..................................................................................................259 11.1 Introduction ................................................................................... 259 11.2 Solid–liquid extraction (leaching) .................................................... 261 11.2.1 Defi nitions ......................................................................... 261 11.2.2 Material balance ................................................................ 262 11.2.3 Equilibrium ........................................................................ 262 11.2.4 Multistage extraction .......................................................... 262 11.2.5 Stage effi ciency .................................................................. 266 11.2.6 Solid–liquid extraction systems ........................................... 268 11.3 Supercritical fl uid extraction ............................................................ 271 11.3.1 Basic principles .................................................................. 271 11.3.2 Supercritical fl uids as solvents ............................................. 272 11.3.3 Supercritical extraction systems ........................................... 273 11.3.4 Applications ....................................................................... 275 11.4 Liquid–liquid extraction .................................................................. 276 11.4.1 Principles ........................................................................... 276 11.4.2 Applications ....................................................................... 276 12 Adsorption and ion exchange .....................................................................279 12.1 Introduction ................................................................................... 279 12.2 Equilibrium conditions .................................................................... 280 12.3 Batch adsorption ............................................................................ 282 12.4 Adsorption in columns .................................................................... 287 Contents ix 12.5 Ion exchange .................................................................................. 288 12.5.1 Basic principles .................................................................. 288 12.5.2 Properties of ion exchangers ............................................... 289 12.5.3 Application: Water softening using ion exchange ................. 292 12.5.4 Application: Reduction of acidity in fruit juices .................... 293 13 Distillation .................................................................................................295 13.1 Introduction ................................................................................... 295 13.2 Vapor–liquid equilibrium (VLE) ........................................................ 295 13.3 Continuous fl ash distillation ............................................................ 298 13.4 Batch (differential) distillation ......................................................... 301 13.5 Fractional distillation ...................................................................... 304 13.5.1 Basic concepts ................................................................... 304 13.5.2 Analysis and design of the column ...................................... 305 13.5.3 Effect of the refl ux ratio ...................................................... 310 13.5.4 Tray confi guration .............................................................. 310 13.5.5 Column confi guration ........................................................ 311 13.5.6 Heating with live steam ...................................................... 311 13.5.7 Energy considerations ......................................................... 312 13.6 Steam distillation ............................................................................ 313 13.7 Distillation of wines and spirits ........................................................ 314 14 Crystallization and dissolution ...................................................................317 14.1 Introduction ................................................................................... 317 14.2 Crystallization kinetics .................................................................... 318 14.2.1 Nucleation ......................................................................... 318 14.2.2 Crystal growth ................................................................... 320 14.3 Crystallization in the food industry .................................................. 323 14.3.1 Equipment ......................................................................... 323 14.3.2 Processes ........................................................................... 325 14.4 Dissolution ..................................................................................... 328 14.4.1 Introduction ...................................................................... 328 14.4.2 Mechanism and kinetics ..................................................... 328 15 Extrusion ...................................................................................................333 15.1 Introduction ................................................................................... 333 15.2 The single-screw extruder ................................................................ 334 15.2.1 Structure ........................................................................... 334 15.2.2 Operation .......................................................................... 335 15.2.3 Flow models, extruder throughput ...................................... 337 15.2.4 Residence time distribution ................................................. 340 15.3 Twin-screw extruders ....................................................................... 340 15.3.1 Structure ........................................................................... 340 15.3.2 Operation .......................................................................... 342 15.3.3 Advantages and shortcomings ............................................ 343 15.4 Effect on foods ............................................................................... 343 15.4.1 Physical effects ................................................................... 343 15.4.2 Chemical effect .................................................................. 344 15.5 Food applications of extrusion ........................................................ 345 15.5.1 Forming extrusion of pasta ................................................. 345 x Contents 15.5.2 Expanded snacks ................................................................ 345 15.5.3 Ready-to-eat cereals ........................................................... 346 15.5.4 Pellets ................................................................................ 347 15.5.5 Other extruded starchy and cereal products ......................... 347 15.5.6 Texturized protein products ................................................ 348 15.5.7 Confectionery and chocolate .............................................. 348 15.5.8 Pet foods ........................................................................... 349 16 Spoilage and preservation of foods ............................................................351 16 .1 Mechanisms of food spoilage .......................................................... 351 16.2 Food preservation processes ............................................................ 351 16.3 Combined processes (the ‘ hurdle effect ’ ) ......................................... 353 16.4 Packaging ....................................................................................... 353 17 Thermal processing ....................................................................................355 17.1 Introduction ................................................................................... 355 17.2 The kinetics of thermal inactivation of microorganisms and enzymes ......................................................................................... 356 17.2.1 The concept of decimal reduction time ................................ 356 17.2.2 Effect of the temperature on the rate of thermal destruction/inactivation ..................................................... 358 17.3 Lethality of thermal processes .......................................................... 360 17.4 Optimization of thermal processes with respect to quality ................ 363 17.5 Heat transfer considerations in thermal processing ........................... 364 17.5.1 In-package thermal processing ............................................ 364 17.5.2 In-fl ow thermal processing .................................................. 369 18 Thermal processes, methods and equipment ..............................................375 18.1 Introduction ................................................................................... 375 18.2 Thermal processing in hermetically closed containers 375 18.2.1 Filling into the cans ............................................................ 376 18.2.2 Expelling air from the head-space ........................................ 378 18.2.3 Sealing ............................................................................... 379 18.2.4 Heat processing ................................................................. 380 18.3 Thermal processing in bulk, before packaging .................................. 386 18.3.1 Bulk heating – hot fi lling – sealing – cooling in container ...... 386 18.3.2 Bulk heating – holding – bulk cooling – cold fi lling – sealing. ..... 386 18.3.3 Aseptic processing .............................................................. 388 19 Refrigeration, chilling and freezing .............................................................391 19.1 Introduction ................................................................................... 391 19.2 Effect of temperature on food spoilage ............................................ 392 19.2.1 Temperature and chemical activity ...................................... 392 19.2.2 Effect of low temperature on enzymatic spoilage ................. 395 19.2.3 Effect of low temperature on microorganisms ...................... 396 19.2.4 Effect of low temperature on biologically active (respiring) tissue ................................................................ 398 19.2.5 The effect of low temperature on physical properties ........... 399 19.3 Freezing .......................................................................................... 400 19.3.1 Phase transition, freezing point ........................................... 401 Contents xi 19.3.2 Freezing kinetics, freezing time ............................................ 402 19.3.3 Effect of freezing and frozen storage on product quality ............................................................................... 408 20 Refrigeration, equipment and methods ......................................................413 20.1 Sources of refrigeration ................................................................... 413 20.1.1 Mechanical refrigeration ..................................................... 413 20.1.2 Refrigerants ....................................................................... 418 20.1.3 Distribution and delivery of refrigeration ............................. 419 20.2 Cold storage and refrigerated transport ........................................... 420 20.3 Chillers and freezers ........................................................................ 423 20.3.1 Blast cooling ...................................................................... 423 20.3.2 Contact freezers ................................................................. 425 20.3.3 Immersion cooling ............................................................. 426 20.3.4 Evaporative cooling ............................................................ 426 21 Evaporation ...............................................................................................429 21.1 Introduction ................................................................................... 429 21.2 Material and energy balance ............................................................ 430 21.3 Heat transfer .................................................................................. 432 21.3.1 The overall coeffi cient of heat transfer U .............................. 433 21.3.2 The temperature difference T S – T C ( Δ T) 436 21.4 Energy management ........................................................................ 440 21.4.1 Multiple-effect evaporation ................................................ 441 21.4.2 Vapor recompression .......................................................... 446 21.5 Condensers .................................................................................... 447 21.6 Evaporators in the food industry ..................................................... 448 21.6.1 Open pan batch evaporator ................................................ 448 21.6.2 Vacuum pan evaporator ..................................................... 449 21.6.3 Evaporators with tubular heat exchangers ........................... 449 21.6.4 Evaporators with external tubular heat exchangers ............... 451 21.6.5 Boiling fi lm evaporators ..................................................... 451 21.7 Effect of evaporation on food quality ............................................... 454 21.7.1 Thermal effects .................................................................. 454 21.7.2 Loss of volatile fl avor components ...................................... 457 22 Dehydration .............................................................................................459 22.1 Introduction ................................................................................... 459 22.2 Thermodynamics of moist air (psychrometry) .................................. 461 22.2.1 Basic principles .................................................................. 461 22.2.2 Humidity ........................................................................... 461 22.2.3 Saturation, relative humidity (RH) ...................................... 462 22.2.4 Adiabatic saturation, wet-bulb temperature ........................ 462 22.2.5 Dew point .......................................................................... 463 22.3 Convective drying (air drying) .......................................................... 464 22.3.1 The drying curve ................................................................. 464 22.3.2 The constant rate phase ..................................................... 467 22.3.3 The falling rate phase ......................................................... 470 22.3.4 Calculation of drying time .................................................. 472 22.3.5 Effect of external conditions on the drying rate .................... 475 xii Contents 22.3.6 Relationship between fi lm coeffi cients in convective drying ... 476 22.3.7 Effect of radiation heating .................................................. 477 22.3.8 Characteristic drying curves ................................................ 477 22.4 Drying under varying external conditions .......................................... 478 22.4.1 Batch drying on trays ......................................................... 478 22.4.2 Through-fl ow batch drying in a fi xed bed ............................. 480 22.4.3 Continuous air drying on a belt or in a tunnel ...................... 481 22.5 Conductive (boiling) drying ............................................................. 481 22.5.1 Basic principles .................................................................. 481 22.5.2 Kinetics .............................................................................. 482 22.5.3 Systems and applications .................................................... 483 22.6 Dryers in the food processing industry ............................................. 485 22.6.1 Cabinet dryers .................................................................... 486 22.6.2 Tunnel dryers ..................................................................... 487 22.6.3 Belt dryers ......................................................................... 489 22.6.4 Belt-trough dryers .............................................................. 489 22.6.5 Rotary dryers ..................................................................... 490 22.6.6 Bin dryers .......................................................................... 490 22.6.7 Grain dryers ....................................................................... 492 22.6.8 Spray dryers ....................................................................... 492 22.6.9 Fluidized bed dryer ............................................................. 497 22.6.10 Pneumatic dryer ................................................................. 498 22.6.11 Drum dryers ....................................................................... 499 22.6.12 Screw conveyor and mixer dryers ......................................... 500 22.6.13 Sun drying, solar drying ...................................................... 501 22.7 Issues in food drying technology ...................................................... 501 22.7.1 Pre-drying treatments ......................................................... 501 22.7.2 Effect of drying conditions on quality .................................. 502 22.7.3 Post-drying treatments ....................................................... 503 22.7.4 Rehydration characteristics ................................................. 503 22.7.5 Agglomeration ................................................................... 504 22.8 Energy consumption in drying ......................................................... 504 22.9 Osmotic dehydration ...................................................................... 507 23 Freeze drying (lyophilization) and freeze concentration ..............................511 23.1 Introduction ................................................................................... 511 23.2 Sublimation of water ...................................................................... 511 23.3 Heat and mass transfer in freeze drying ............................................ 512 23.4 Freeze drying, in practice ................................................................. 518 23.4.1 Freezing ............................................................................. 518 23.4.2 Drying conditions ............................................................... 518 23.4.3 Freeze drying, commercial facilities ..................................... 518 23.4.4 Freeze dryers ...................................................................... 519 23.5 Freeze concentration ....................................................................... 520 23.5.1 Basic principles .................................................................. 520 23.5.2 The process of freeze concentration .................................... 521 24 Frying, baking, roasting .............................................................................525 24.1 Introduction ................................................................................... 525 Contents xiii 24.2 Frying ............................................................................................. 525 24.2.1 Types of frying .................................................................... 525 24.2.2 Heat and mass transfer in frying .......................................... 526 24.2.3 Systems and operation ....................................................... 527 24.2.4 Health aspects of fried foods .............................................. 528 24.3 Baking and roasting ........................................................................ 528 25 Ionizing irradiation and other non-thermal preservation processes 533 25.1 Preservation by ionizing radiations ................................................... 533 25.1.1 Introduction ...................................................................... 533 25.1.2 Ionizing radiations ............................................................. 533 25.1.3 Radiation sources .............................................................. 534 25.1.4 Interaction with matter ....................................................... 535 25.1.5 Radiation dose ................................................................... 537 25.1.6 Chemical and biological effects of ionizing irradiation ......... 538 25.1.7 Industrial applications ........................................................ 540 25.2 High hydrostatic pressure preservation ............................................ 541 25.3 Pulsed electric fi elds (PEF) ............................................................... 542 25.4 Pulsed intense light ......................................................................... 542 26 Food packaging .........................................................................................545 26.1 Introduction ................................................................................... 545 26.2 Packaging materials ........................................................................ 546 26.2.1 Introduction ...................................................................... 546 26.2.2 Materials for packaging foods ............................................. 548 26.2.3 Transport properties of packaging materials ........................ 551 26.2.4 Optical properties .............................................................. 553 26.2.5 Mechanical properties ........................................................ 554 26.2.6 Chemical reactivity ............................................................. 555 26.3 The atmosphere in the package ....................................................... 556 26.3.1 Vacuum packaging ............................................................. 556 26.3.2 Controlled atmosphere packaging (CAP) ............................ 557 26.3.3 Modifi ed atmosphere packaging (MAP) .............................. 557 26.3.4 Active packaging ................................................................ 557 26.4 Environmental issues ....................................................................... 558 27 Cleaning, disinfection, sanitation ...............................................................561 27.1 Introduction ................................................................................... 561 27.2 Cleaning kinetics and mechanisms ................................................... 562 27.2.1 Effect of the contaminant ................................................... 562 27.2.2 Effect of the support .......................................................... 564 27.2.3 Effect of the cleaning agent ................................................. 564 27.2.4 Effect of the temperature .................................................... 566 27.2.5 Effect of mechanical action (shear) ..................................... 566 27.3 Kinetics of disinfection .................................................................... 567 27.4 Cleaning of raw materials ................................................................ 568 27.5 Cleaning of plants and equipment ................................................... 570 27.5.1 Cleaning out of place (COP) ............................................... 570 27.5.2 Cleaning in place (CIP) ....................................................... 570 27.6 Cleaning of packages ...................................................................... 571 27.7 Odor abatement ............................................................................. 571 xiv Contents Appendix ...........................................................................................................575 Table A.1 Common conversion factors ...................................................... 576 Table A.2 Typical composition of selected foods ........................................ 577 Table A.3 Viscosity and density of gases and liquids ................................... 578 Table A.4 Thermal properties of materials ................................................. 578 Table A.5 Emissivity of surfaces ................................................................. 579 Table A.6 US standard sieves ..................................................................... 579 Table A.7 Properties of saturated steam – temperature table ...................... 580 Table A.8 Properties of saturated steam – pressure table ............................ 581 Table A.9 Properties of superheated steam ................................................. 581 Table A.10 Vapor pressure of liquid water and ice below 0°C ....................... 582 Table A.11 Freezing point of ideal aqueous solutions .................................... 583 Table A.12 Vapor–liquid equilibrium data for ethanol–water mixtures at 1 atm ....................................................................... 583 Table A.13 Boiling point of sucrose solutions at 1 atm .................................. 584 Table A.14 Electrical conductivity of some materials ..................................... 584 Table A.15 Thermodynamic properties of saturated R-134a .......................... 584 Table A.16 Thermodynamic properties of superheated R-134a ..................... 585 Table A.17 Properties of air at atmospheric pressure .................................... 586 Figure A.1 Friction factors for fl ow in pipes ................................................. 587 Figure A.2 Psychrometric chart ................................................................... 587 Figure A.3 Mixing power function, turbine impellers .................................... 588 Figure A.4 Mixing power function, propeller impellers .................................. 588 Figure A.5 Unsteady state heat transfer in a slab .......................................... 589 Figure A.6 Unsteady state heat transfer in an infi nite cylinder ....................... 589 Figure A.7 Unsteady state heat transfer in a sphere ...................................... 590 Figure A.8 Unsteady state mass transfer, average concentration ................... 590 Figure A.9 Error function ............................................................................ 591 Index ..........................................................................................................593 Series List ....................................................................................................603
Includes bibliographical references and index.
"The last thirty years have seen the establishment of Food Engineering both as an academic discipline and as a profession. Combining scientific depth with practical usefulness, this book serves as a tool for graduate students as well as practicing food engineers, technologists and researchers looking for the latest information on transformation and preservation processes as well as process control and plant hygiene topics."--publisher's website.
0124159230 9780124159235
2015300526
Food industry and trade--Technological innovations. Food processing plants.