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Fundamentals of Food Process Engineering. Fourth Edition

Fundamentals of Food Process Engineering. Fourth Edition

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Romeo T. Toledo
Rakesh K. Singh
Fanbin Kong


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Book Details
 Price
 3.00
 Pages
 463 p
 File Size 
 16,419 KB
 File Type
 PDF format
 ISBN
 978-3-319-90097-1
 978-3-319-90098-8 (eBook)
 Copyright©   
 Springer International Publishing AG,
 part of Springer Nature 2007, 2018 2nd edition 
 ©Aspen Publishers, Inc. 1999

Preface
Since the publication of the first edition in 1981, the second edition in 2001,
and the third edition in 2007, this textbook has been widely adopted for Food
Engineering courses worldwide. The authors express their gratitude to
colleagues who have adopted this textbook and to those who have made
constructive criticisms on the materials in the previous editions. This new
edition not only incorporates changes suggested by colleagues, but additional
materials have been added to include facilitated problem-solving using a
computer and new food processing and food product technologies, such
aseptic processing and emerging food processing technologies. New sections
have been added in most of the chapters reflecting the current state of the
technology. The expanded coverage may result in not enough time available
in a school term to cover all areas; therefore, instructors are advised to
carefully peruse the book and select the most appropriate sections to cover
in a school term. The advantage of the expanded coverage is the elimination of
the need for a supplementary textbook.

The success of this textbook has been attributed to the expansive coverage
of subject areas specified in the Institute of Food Technologists model curriculum
for food science majors in the USA and the use of examples utilizing
conditions encountered in actual food processing operations. This theme
continues in the fourth edition. In addition to the emphasis on problemsolving,
technological principles that form the basis for a process are
presented so that the process can be better understood and selection of
processing parameters to maximize product quality and safety can be made
more effective. The fourth edition incorporates most of what was in the third
edition with most of the material updated to include the use of computers in
problem-solving. Use of the spreadsheet and macros such as the determinant
for solving simultaneous linear equations, the solver function, and programming
in Visual BASIC are used throughout the book. The manual problemsolving
approach has not been abandoned in favor of the computer approach.

Thus, users can still apply the concepts to better understand a process rather
than just mechanically entering inputs into a preprogrammed algorithm.
Entirely new sections include enthalpy change calculations in freezing
based on the freezing point depression, evaporative cooling, interpretation
of pump performance curves, determination of shape factors in heat exchange
by radiation, unsteady-state heat transfer, kinetic data for thermal degradation
of foods during thermal processing, pasteurization parameters for shelf-stable
high-acid foods and long-life refrigerated low-acid foods, high-pressure
processing of fluid and packaged foods, concentration of juices, environmentally
friendly refrigerants, modified atmosphere packaging of produce, sorption
equations for water activity of solid foods, the osmotic pressure and water
activity relationships, vacuum dehydration, new membranes commercially
available for food processing and waste treatment, and supercritical fluid extraction.

This edition contains much new hard-to-find data needed to conduct food
process engineering calculations and will be very useful as a sourcebook of
data and calculation techniques for practicing food engineers.
Athens, GA, USA 
Romeo T. Toledo
Rakesh Singh
Fanbin Kong



Table of Contents
1 Units and Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Definition of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Systems of Measurement . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 The SI System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3.1 Units in SI and Their Symbols . . . . . . . . . . . . . 2
1.3.2 Prefixes Recommended for Use in SI . . . . . . . . 2
1.4 Conversion of Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4.1 Precision, Rounding-Off Rule,
and Significant Digits . . . . . . . . . . . . . . . . . . . 3
1.5 The Dimensional Equation . . . . . . . . . . . . . . . . . . . . . . . 4
1.6 Conversion of Units Using the Dimensional Equation . . . 4
1.7 The Dimensional Constant (Gc) . . . . . . . . . . . . . . . . . . . 5
1.8 Determination of Appropriate SI Units . . . . . . . . . . . . . . 6
1.9 Dimensional Consistency of Equations . . . . . . . . . . . . . . 7
1.10 Conversion of Dimensional Equations . . . . . . . . . . . . . . . 7
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 Material Balances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1 Basic Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.1 Law of Conservation of Mass . . . . . . . . . . . . . . 11
2.1.2 Process Flow Diagrams . . . . . . . . . . . . . . . . . . 11
2.1.3 System Boundaries . . . . . . . . . . . . . . . . . . . . . 12
2.1.4 Total Mass Balance . . . . . . . . . . . . . . . . . . . . . 13
2.1.5 Component Mass Balance . . . . . . . . . . . . . . . . 14
2.1.6 Basis and “Tie Material” . . . . . . . . . . . . . . . . . 16
2.2 Material Balance Problems Involved in Dilution,
Concentration, and Dehydration . . . . . . . . . . . . . . . . . . . 16
2.2.1 Steady State . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.2.2 Volume Changes on Mixing . . . . . . . . . . . . . . 17
2.2.3 Continuous Versus Batch . . . . . . . . . . . . . . . . . 18
2.2.4 Recycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2.5 Unsteady State . . . . . . . . . . . . . . . . . . . . . . . . 20
2.3 Blending of Food Ingredients . . . . . . . . . . . . . . . . . . . . . 22
2.3.1 Total Mass and Component Balances . . . . . . . . 22
2.3.2 Use of Specified Constraints in Equations . . . . . 25
2.4 Multistage Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3 Gases and Vapors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.1 Equations of State for Ideal and Real Gases . . . . . . . . . . . 41
3.1.1 The Kinetic Theory of Gases . . . . . . . . . . . . . . 41
3.1.2 Absolute Temperature and Pressure . . . . . . . . . 42
3.1.3 Quantity of Gases . . . . . . . . . . . . . . . . . . . . . . 43
3.1.4 The Ideal Gas Equation . . . . . . . . . . . . . . . . . . 44
3.1.5 Van Der Waals Equation of State . . . . . . . . . . . 45
3.1.6 Critical Conditions for Gases . . . . . . . . . . . . . . 47
3.1.7 Gas Mixtures . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.2 Thermodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.2.1 Thermodynamic Variables . . . . . . . . . . . . . . . . 49
3.2.2 The Relationship Between Cp and Cv
for Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.2.3 P-V-T Relationships for Ideal Gases
in Thermodynamic Processes . . . . . . . . . . . . . . 50
3.2.4 Changes in Thermodynamic Properties, Work,
and Heat Associated with Thermodynamic
Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.2.5 Work and Enthalpy Change on Adiabatic
Expansion or Compression of an Ideal Gas . . . . 51
3.2.6 Work and Enthalpy Change on Isothermal
Expansion or Compression of an Ideal Gas . . . . 52
3.3 Vapor-Liquid Equilibrium . . . . . . . . . . . . . . . . . . . . . . . 52
3.3.1 The Clausius-Clapeyron Equation . . . . . . . . . . . 53
3.3.2 Liquid Condensation from Gas Mixtures . . . . . . 53
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4 Energy Balances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.1 General Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.2 Energy Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.2.1 Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.2.2 Heat Content, Enthalpy . . . . . . . . . . . . . . . . . . 58
4.2.3 Specific Heat of Solids and Liquids . . . . . . . . . 58
4.3 Enthalpy Changes in Foods During Freezing . . . . . . . . . . 63
4.3.1 Correlation Equations Based on Freezing
Points of Food Products Unmodified
from the Natural State . . . . . . . . . . . . . . . . . . . 63
4.3.2 Enthalpy Changes During the Freezing
of Foods Calculated from Molality of Liquid
Water Fraction of the Food . . . . . . . . . . . . . . . 64
4.3.3 Freezing Point Depression by Solutes . . . . . . . . 64
4.3.4 Amount of Liquid Water and Ice at Temperatures
Below Freezing . . . . . . . . . . . . . . . . . . . . . . . . 65
4.3.5 Sensible Heat of Water and Ice
at Temperatures Below the Freezing Point . . . . 65
4.3.6 Total Enthalpy Change . . . . . . . . . . . . . . . . . . 65
4.3.7 Specific Heats of Gases and Vapors . . . . . . . . . 66
4.4 Properties of Saturated and Superheated Steam . . . . . . . . 68
4.4.1 The Steam Tables . . . . . . . . . . . . . . . . . . . . . . 68
4.4.2 Properties of Steam Having Less Than 100%
Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.5 Heat Balances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5 Flow of Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.1 The Concept of Viscosity . . . . . . . . . . . . . . . . . . . . . . . . 81
5.2 Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.2.1 Viscometry . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.2.2 Effect of Temperature on Rheological
Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
5.2.3 Back Extrusion . . . . . . . . . . . . . . . . . . . . . . . . 94
5.2.4 Determination of Rheological Properties
of Fluids Using Rotational Viscometers . . . . . . 99
5.3 Continuous Viscosity Monitoring and Control . . . . . . . . . 104
5.3.1 Capillary Viscometer . . . . . . . . . . . . . . . . . . . . 105
5.3.2 Rotational Viscometer . . . . . . . . . . . . . . . . . . . 105
5.3.3 Viscosity-Sensitive Rotameter . . . . . . . . . . . . . 106
5.4 Flow of Falling Films . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
5.4.1 Films of Constant Thickness . . . . . . . . . . . . . . 106
5.4.2 Time-Dependent Film Thickness . . . . . . . . . . . 108
5.4.3 Processes Dependent on Fluid Film
Thicknesses . . . . . . . . . . . . . . . . . . . . . . . . . . 110
5.5 Transportation of Fluids . . . . . . . . . . . . . . . . . . . . . . . . . 111
5.5.1 Momentum Balance . . . . . . . . . . . . . . . . . . . . 111
5.5.2 The Continuity Principle . . . . . . . . . . . . . . . . . 112
5.6 Fluid Flow Regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
5.6.1 The Reynolds Number . . . . . . . . . . . . . . . . . . . 113
5.6.2 Pipes and Tubes . . . . . . . . . . . . . . . . . . . . . . . 114
5.6.3 Frictional Resistance to Flow of Newtonian
Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
5.6.4 Frictional Resistance to Flow of Non-Newtonian
Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
5.6.5 Frictional Resistance Offered by Pipe Fittings
to Fluid Flow . . . . . . . . . . . . . . . . . . . . . . . . . 119
5.7 Mechanical Energy Balance: The Bernoulli Equation . . . . 120
5.8 Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
5.8.1 Types of Pumps and Their Characteristics . . . . . 124
5.8.2 Factors to Be Considered in Pump Selection . . . 124
5.8.3 Performance Curves of Pumps . . . . . . . . . . . . . 125
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
6 Heat Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
6.1 Mechanisms of Heat Transfer . . . . . . . . . . . . . . . . . . . . . 135
6.1.1 Heat Transfer by Conduction . . . . . . . . . . . . . . 135
6.1.2 Fourier’s First Law of Heat Transfer . . . . . . . . . 135
6.1.3 Estimation of Thermal Conductivity of Food
Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
6.1.4 Fourier’s Second Law of Heat Transfer . . . . . . . 138
6.1.5 Temperature Profile for Unidirectional Heat
Transfer Through a Slab . . . . . . . . . . . . . . . . . 139
6.1.6 Conduction Heat Transfer Through Walls
of a Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . 141
6.1.7 The Temperature Profile in the Walls
of a Cylinder in Steady-State Heat Transfer . . . . 141
6.1.8 Heat Transfer by Convection . . . . . . . . . . . . . . 142
6.1.9 Heat Transfer by Radiation . . . . . . . . . . . . . . . 143
6.1.10 Microwave and Dielectric Heating . . . . . . . . . . 149
6.2 Temperature Measuring Devices . . . . . . . . . . . . . . . . . . . 152
6.2.1 Liquid-in-Glass Thermometers . . . . . . . . . . . . . 153
6.2.2 Fluid-Filled Thermometers . . . . . . . . . . . . . . . . 153
6.2.3 Bimetallic Strip Thermometers . . . . . . . . . . . . . 153
6.2.4 Resistance Temperature Devices (RTDs) . . . . . . 154
6.2.5 Thermocouples . . . . . . . . . . . . . . . . . . . . . . . . 154
6.2.6 Radiation Pyrometers . . . . . . . . . . . . . . . . . . . . 154
6.2.7 Accurate Temperature Measurements . . . . . . . . 155
6.3 Steady-State Heat Transfer . . . . . . . . . . . . . . . . . . . . . . . 155
6.3.1 The Concept of Resistance to Heat Transfer . . . 155
6.3.2 Combined Convection and Conduction:
The Overall Heat Transfer Coefficient . . . . . . . . 156
6.4 Heat Exchange Equipment . . . . . . . . . . . . . . . . . . . . . . . 158
6.4.1 Heat Transfer in Heat Exchangers . . . . . . . . . . . 160
6.4.2 The Logarithmic Mean Temperature
Difference . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
6.5 Local Heat Transfer Coefficients . . . . . . . . . . . . . . . . . . . 162
6.5.1 Dimensionless Quantities . . . . . . . . . . . . . . . . . 162
6.5.2 Equations for Calculating Heat Transfer
Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
6.6 Unsteady-State Heat Transfer . . . . . . . . . . . . . . . . . . . . . 169
6.6.1 Heating of Solids Having Infinite Thermal
Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . 169
6.6.2 Solids with Finite Thermal Conductivity . . . . . . 170
6.6.3 The Semi-Infinite Slab with Constant
Surface Temperature . . . . . . . . . . . . . . . . . . . . 171
6.6.4 The Infinite Slab . . . . . . . . . . . . . . . . . . . . . . . 172
6.6.5 Temperature Distribution for a Brick-Shaped
Solid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
6.6.6 Use of Heisler and Gurney-Lurie Charts . . . . . . 174
6.7 Calculating Surface Heat Transfer Coefficients
from Experimental Heating Curves . . . . . . . . . . . . . . . . . 175
6.8 Freezing Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Suggested Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
7 Kinetics of Chemical Reactions in Foods . . . . . . . . . . . . . . . . 183
7.1 Theory of Reaction Rates . . . . . . . . . . . . . . . . . . . . . . . . 183
7.2 Types of Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
7.2.1 Unimolecular Reactions . . . . . . . . . . . . . . . . . . 183
7.2.2 Bimolecular Reactions . . . . . . . . . . . . . . . . . . . 184
7.2.3 Reversible Reactions . . . . . . . . . . . . . . . . . . . . 184
7.3 Enzyme Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
7.4 Reaction Order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
7.4.1 Zero-Order Reactions . . . . . . . . . . . . . . . . . . . 187
7.4.2 First-Order Reactions . . . . . . . . . . . . . . . . . . . . 187
7.4.3 Second-Order Reactions . . . . . . . . . . . . . . . . . 187
7.4.4 nth-Order Reactions . . . . . . . . . . . . . . . . . . . . . 188
7.5 Reactions Where Product Concentration Is Rate
Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
7.6 The Reaction Rate Constant . . . . . . . . . . . . . . . . . . . . . . 189
7.7 Temperature Dependence of Reaction Rates . . . . . . . . . . 189
7.7.1 The Arrhenius Equation . . . . . . . . . . . . . . . . . . 189
7.7.2 The Q10 Value . . . . . . . . . . . . . . . . . . . . . . . . 190
7.7.3 The z Value . . . . . . . . . . . . . . . . . . . . . . . . . . 190
7.8 Determination of Reaction Kinetic Parameters . . . . . . . . . 191
7.9 Use of Chemical Reaction Kinetic Data for Thermal
Process Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
8 Thermal Process Calculations . . . . . . . . . . . . . . . . . . . . . . . . 195
8.1 Processes and Systems for Stabilization of Foods for Shelf-
Stable Storage: Systems Requirements . . . . . . . . . . . . . . 195
8.1.1 In-Container Processing . . . . . . . . . . . . . . . . . . 195
8.1.2 Processing Products Packaged in Flexible Plastic
Containers . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
8.1.3 Processing in Glass Containers . . . . . . . . . . . . . 199
8.1.4 Flame Sterilization Systems . . . . . . . . . . . . . . . 200
8.1.5 Continuous Flow Sterilization: Aseptic
or Cold Fill . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
8.1.6 Steam-Air Mixtures for Thermal Processing . . . 201
8.2 Microbiological Inactivation Rates at Constant Temperature 201
8.2.1 Rate of Microbial Inactivation . . . . . . . . . . . . . 201
8.2.2 Shape of Microbial Inactivation Curves . . . . . . 202
8.2.3 Sterilizing Value or Lethality of a Process . . . . . 204
8.2.4 Acceptable Sterilizing Value for Processes . . . . 205
8.2.5 Selection of Inoculation Levels in Inoculated
Packs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
8.2.6 Determination of D Values Using
the Partial Sterilization Technique . . . . . . . . . . 207
8.2.7 The Heat Resistance of Spoilage Microorganisms 207
8.2.8 F0 Values Used in Commercial Sterilization
of Canned Foods . . . . . . . . . . . . . . . . . . . . . . . 207
8.2.9 Surface Sterilization . . . . . . . . . . . . . . . . . . . . 207
8.3 Effect of Temperature on Thermal Inactivation of
Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
8.4 Inactivation of Microorganisms and Enzymes in
Continuously Flowing Fluids . . . . . . . . . . . . . . . . . . . . . 211
8.4.1 Time and Temperature Used in the Pasteurization
of Fluid Foods . . . . . . . . . . . . . . . . . . . . . . . . 211
8.4.2 Microbial Inactivation in Continuously
Flowing Fluids . . . . . . . . . . . . . . . . . . . . . . . . 213
8.4.3 Nutrient Degradation . . . . . . . . . . . . . . . . . . . . 216
8.4.4 High-Pressure Pasteurization . . . . . . . . . . . . . . 219
8.4.5 Sterilization of Fluids Containing Discreet
Particulates by Heat . . . . . . . . . . . . . . . . . . . . . 222
8.5 Sterilizing Value of Processes Expressed as F0 . . . . . . . . . 223
8.6 Thermal Process Calculations for Canned Foods . . . . . . . 223
8.6.1 The General Method . . . . . . . . . . . . . . . . . . . . 224
8.6.2 Heat Transfer Equations and Time-Temperature
Curves for Canned Foods . . . . . . . . . . . . . . . . . 225
8.6.3 Plotting Heat Penetration Data . . . . . . . . . . . . . 227
8.6.4 Formula Methods for Thermal Process Evaluation 231
8.6.5 Evaluation of Probability of Spoilage from a
Given Process . . . . . . . . . . . . . . . . . . . . . . . . . 233
8.7 Broken Heating Curves . . . . . . . . . . . . . . . . . . . . . . . . . 236
8.8 Quality Factor Degradation . . . . . . . . . . . . . . . . . . . . . . . 239
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
9 Aseptic Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
9.1 The System and Its Elements . . . . . . . . . . . . . . . . . . . . . 245
9.2 Characteristics of Specific Elements . . . . . . . . . . . . . . . . 245
9.2.1 Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . 246
9.2.2 Heat Transfer/Cooling . . . . . . . . . . . . . . . . . . . 247
9.2.3 Hold Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
9.2.4 Deaerators . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
9.2.5 Aseptic Surge Tank . . . . . . . . . . . . . . . . . . . . . 252
9.3 Thermal Process for the Product . . . . . . . . . . . . . . . . . . . 252
9.3.1 Influence of Product Characteristics . . . . . . . . . 252
9.3.2 Thermal Process Calculations . . . . . . . . . . . . . . 253
9.4 Flow Characteristics of Product . . . . . . . . . . . . . . . . . . . 256
9.4.1 Residence Time Distribution (RTD) . . . . . . . . . 258
9.5 Heat Transfer to Product . . . . . . . . . . . . . . . . . . . . . . . . 269
9.6 Filling and Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
9.7 Monitors and Controls . . . . . . . . . . . . . . . . . . . . . . . . . . 272
9.8 Processing System Sterilization . . . . . . . . . . . . . . . . . . . . 273
9.8.1 Maintenance of Sterility . . . . . . . . . . . . . . . . . . 274
9.8.2 Process Confirmation . . . . . . . . . . . . . . . . . . . . 274
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
10 Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
10.1 Mechanical Refrigeration System . . . . . . . . . . . . . . . . . . 277
10.1.1 Principle of Operation: The Heat Pump . . . . . . . 277
10.1.2 Refrigerants . . . . . . . . . . . . . . . . . . . . . . . . . . 278
10.1.3 The Refrigeration Cycle . . . . . . . . . . . . . . . . . . 279
10.1.4 The Refrigeration Cycle as a Series of
Thermodynamic Processes . . . . . . . . . . . . . . . . 281
10.1.5 The Refrigeration Cycle on the Pressure/Enthalpy
Diagram for a Given Refrigerant . . . . . . . . . . . 281
10.1.6 The Condenser and Evaporator . . . . . . . . . . . . . 288
10.1.7 The Compressor . . . . . . . . . . . . . . . . . . . . . . . 290
10.2 Refrigeration Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
10.2.1 Heat Incursion Through Enclosures . . . . . . . . . 292
10.2.2 Heat Incursion Through Cracks
and Crevices . . . . . . . . . . . . . . . . . . . . . . . . . . 292
10.2.3 Heat Incursion Through Open Doors . . . . . . . . 293
10.2.4 Heat Generation . . . . . . . . . . . . . . . . . . . . . . . 293
10.2.5 The Unsteady-State Refrigeration Load . . . . . . . 295
10.3 Commodity Storage Requirements . . . . . . . . . . . . . . . . . 296
10.4 Controlled Atmosphere Storage . . . . . . . . . . . . . . . . . . . 296
10.4.1 Respiration . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
10.4.2 CA Gas Composition . . . . . . . . . . . . . . . . . . . . 298
10.5 Modified Atmosphere Packaging . . . . . . . . . . . . . . . . . . . 301
10.5.1 Modified Atmosphere Packaging of Fruit,
Vegetables, Bakery Products, and Nuts . . . . . . . 301
10.5.2 MAP of Fresh Ready to Cook Meats . . . . . . . . 302
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
11 Evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
11.1 Single-Effect Evaporators . . . . . . . . . . . . . . . . . . . . . . . . 307
11.1.1 The Vapor Chamber . . . . . . . . . . . . . . . . . . . . 307
11.1.2 The Condenser . . . . . . . . . . . . . . . . . . . . . . . . 309
11.1.3 Removal of Noncondensible Gases . . . . . . . . . . 310
11.1.4 The Heat Exchanger . . . . . . . . . . . . . . . . . . . . 312
11.2 Improving the Economy of Evaporators . . . . . . . . . . . . . . 314
11.2.1 Vapor Recompression . . . . . . . . . . . . . . . . . . . 314
11.2.2 Multiple-Effect Evaporators . . . . . . . . . . . . . . . 316
11.2.3 Entrainment . . . . . . . . . . . . . . . . . . . . . . . . . . 318
11.2.4 Essence Recovery . . . . . . . . . . . . . . . . . . . . . . 318
11.2.5 Temperature-Accelerated Short-Time Evaporator
(TASTE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
12 Dehydration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
12.1 Water Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
12.1.1 Thermodynamic Basis for Water Activity . . . . . 321
12.1.2 Osmotic Pressure . . . . . . . . . . . . . . . . . . . . . . . 322
12.1.3 Water Activity at High Moisture Contents . . . . . 323
12.1.4 Water Activity at Low Moisture Contents . . . . . 327
12.2 Mass Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
12.2.1 Mass Diffusion . . . . . . . . . . . . . . . . . . . . . . . . 330
12.2.2 Mass Transfer from Surfaces
to Flowing Air . . . . . . . . . . . . . . . . . . . . . . . . 332
12.3 Psychrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334
12.3.1 Carrying Capacity of Gases for Vapors . . . . . . . 334
12.3.2 The Psychrometric Chart . . . . . . . . . . . . . . . . . 335
12.3.3 Use of Psychrometric Chart to Follow
Changes in the Properties of Air-Water Mixtures
Through a Process . . . . . . . . . . . . . . . . . . . . . . 337
12.4 Simultaneous Heat and Mass Transfer in Dehydration . . . 338
12.5 The Stages of Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . 339
12.6 Prediction of Drying Times from Drying Rate Data . . . . . 340
12.6.1 Materials with One Falling Rate Stage
Where the Rate of Drying Curve Goes
Through the Origin . . . . . . . . . . . . . . . . . . . . . 340
12.6.2 Materials with More than One Falling
Rate Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
12.6.3 The Constant Drying Rate . . . . . . . . . . . . . . . . 342
12.7 Spray Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
12.7.1 Drying Times in Spray Drying . . . . . . . . . . . . . 345
12.8 Freeze Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
12.8.1 Drying Times for Symmetrical Drying . . . . . . . 349
12.9 Vacuum Belt Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
13 Physical Separation Processes . . . . . . . . . . . . . . . . . . . . . . . . 355
13.1 Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
13.1.1 Filtrate Flow Through Filter Cake . . . . . . . . . . 356
13.1.2 Constant Pressure Filtration . . . . . . . . . . . . . . . 358
13.1.3 Filtration Rate Model Equations for Prolonged
Filtration When Filter Cakes Exhibit
Time-Dependent Specific Resistance . . . . . . . . 360
13.1.4 Exponential Dependence of Rate on Filtrate
Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
13.1.5 Model Equation Based on Time-Dependent
Specific Cake Resistance . . . . . . . . . . . . . . . . . 362
13.1.6 Optimization of Filtration Cycles . . . . . . . . . . . 363
13.1.7 Pressure-Driven Membrane Separation Processes 365
13.1.8 Membrane System Configurations . . . . . . . . . . 367
13.1.9 Transmembrane Flux in Pressure-Driven
Membrane Separation Processes
(Polarization Concentration and Fouling) . . . . . 368
13.1.10 Solute Rejection . . . . . . . . . . . . . . . . . . . . . . . 371
13.1.11 Sterilizing Filtrations . . . . . . . . . . . . . . . . . . . . 371
13.1.12 Ultrafiltration . . . . . . . . . . . . . . . . . . . . . . . . . 373
13.1.13 Reverse Osmosis . . . . . . . . . . . . . . . . . . . . . . . 373
13.1.14 Temperature Dependence of Membrane
Permeation Rates . . . . . . . . . . . . . . . . . . . . . . . 377
13.1.15 Other Membrane Separation Processes . . . . . . . 377
13.2 Sieving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378
13.2.1 Standard Sieve Sizes . . . . . . . . . . . . . . . . . . . . 378
13.3 Gravity Separations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
13.3.1 Force Balance on Particles Suspended
in a Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
13.3.2 Terminal Velocity . . . . . . . . . . . . . . . . . . . . . . 380
13.3.3 The Drag Coefficient . . . . . . . . . . . . . . . . . . . . 381
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
14 Extraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385
14.1 Types of Extraction Processes . . . . . . . . . . . . . . . . . . . . . 386
14.1.1 Single-Stage Batch Processing . . . . . . . . . . . . . 386
14.1.2 Multistage Cross-Flow Extraction . . . . . . . . . . . 386
14.1.3 Multistage Countercurrent Extraction . . . . . . . . 386
14.1.4 Continuous Countercurrent Extractors . . . . . . . . 387
14.2 General Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
14.2.1 Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
14.2.2 Solubility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
14.2.3 Equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
14.3 Solid-Liquid Extraction: Leaching . . . . . . . . . . . . . . . . . . 389
14.3.1 The Extraction Battery: Number
of Extraction Stages . . . . . . . . . . . . . . . . . . . . . 389
14.3.2 Determination of the Number of Extraction
Stages Using the Ponchon-Savarit Diagram . . . . 390
14.3.3 The Lever Rule in Plotting Position of a Mixture
of Two Streams in an X-Y Diagram . . . . . . . . . 390
14.3.4 Mathematical and Graphical Representation
of the Point J in the Ponchon-Savarit
Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392
14.3.5 Mathematical and Graphical Representation
of the Point P. . . . . . . . . . . . . . . . . . . . . . . . . 392
14.3.6 Equation of the Operating Line and
Representation on the X-Y Diagram . . . . . . . . . 393
14.3.7 Construction of the Ponchon-Savarit
Diagram for the Determination
of the Number of Ideal Extraction Stages . . . . . 393
14.4 Supercritical Fluid Extraction . . . . . . . . . . . . . . . . . . . . . 398
14.4.1 Extraction Principles . . . . . . . . . . . . . . . . . . . . 398
14.4.2 Critical Points of Supercritical Fluids
Used in Foods . . . . . . . . . . . . . . . . . . . . . . . . . 399
14.4.3 Critical Point of Mixtures . . . . . . . . . . . . . . . . . 399
14.4.4 Properties of Supercritical Fluids Relative
to Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
14.4.5 Supercritical Fluid Extraction Parameters . . . . . 399
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402
15 Emerging Food Processing Technologies . . . . . . . . . . . . . . . . 403
15.1 Microwave and Radio Frequency Heating . . . . . . . . . . . . 403
15.1.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . 403
15.1.2 Heat Generation by MW and RF in Food . . . . . 405
15.1.3 Penetration Depth of Microwave
and Radio-Frequency Waves in Food . . . . . . . . 407
15.1.4 Technical Design . . . . . . . . . . . . . . . . . . . . . . . 408
15.1.5 Research Status and Applications . . . . . . . . . . . 410
15.2 High-Pressure Processing . . . . . . . . . . . . . . . . . . . . . . . . 411
15.2.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . 411
15.2.2 Technical Design . . . . . . . . . . . . . . . . . . . . . . . 412
15.2.3 Research Status and Applications . . . . . . . . . . . 415
15.3 Pulse Electric Field Processing . . . . . . . . . . . . . . . . . . . . 416
15.3.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . 416
15.3.2 Technical Design . . . . . . . . . . . . . . . . . . . . . . . 418
15.3.3 Research Status and Applications . . . . . . . . . . . 420
Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420
Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422
Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445


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