1 Food drying fundamentals
1.1 Introduction to food materials
1.2 Drying of food
1.3 Physical properties of foods
1.3.1 The scales of interest
1.3.2 Mechanical properties
1.3.3 Shrinkage and densities
1.3.4 Thermal properties and conventional heating
1.3.5 Colour
1.3.6 Equilibrium isotherms
1.4 Drying rate characteristic curve approach to correlate drying rates
1.5 Diffusion theories of drying
1.5.1 Effectiv[...]
1 Food drying fundamentals
1.1 Introduction to food materials
1.2 Drying of food
1.3 Physical properties of foods
1.3.1 The scales of interest
1.3.2 Mechanical properties
1.3.3 Shrinkage and densities
1.3.4 Thermal properties and conventional heating
1.3.5 Colour
1.3.6 Equilibrium isotherms
1.4 Drying rate characteristic curve approach to correlate drying rates
1.5 Diffusion theories of drying
1.5.1 Effective Fickian diffusivity
1.5.2 Intuitive understanding of the diffusion theory
1.5.3 Drying offoods simulated using the effective Fickian diffusion law
1.5.4 Alternative effective diffusion theories
1.6 Driers
1.7 Concluding remarks
1.8 Notation
Appendix I: Typical mass transfer correlations
Appendix II: On the 'effectiveness' of the effective moisture diffusivity benchmarked against the Luikov theory
Appendix III: Drying of pulped Kiwi fruit layer for making fruit leather
References
2.1 Introduction
2.1.1 Thermodynamics of water activity
2.1.2 Definition and significance
2.1.3 Sorption isotherms
2.1.4 Hysteresis in sorption isotherms
2.2 Composition-based water activity predictive models
2.2.1 Raoult's Law
2.2.2 Norrish model
2.2.3 Ross model
2.2.4 Money-Born equation
2.2.5 Grover model
2.2.6 Salwin equation
2.3 Models for prediction of sorption isotherms
2.3.1 Two-parameter models
2.3.2 Three-parameter isotherms
2.3.3 Effect of temperature on water activity
2.3.4 Water activity above boiling point
2.4 Types of sorption isotherms and hysteresis in isotherms
2.5 Determination of sorption isotherms
2.5.1 Gravimetric method
2.5.2 Manometric method
2.5.3 Hygroscopic methods
2.5.4 Sample preparation and equilibrium time
2.6 Concluding remarks
References
3 Biological changes during food drying processes
3.1 Introduction to drying and food quality
3.2 Post-drying problems
3.3 In-drying problems
3.4 Food bio-deterioration by drying - a sub-cell level approach
3.5 Concluding remarks
3.6 Notation
References
4 Spray drying of food materials - process and product characteristics
4.1 Introduction
4.2 Basic concepts of spray drying
4.3 Components of a spray drying system
4.3.1 Drying gas supply and heating system
4.3.2 Atomization system
4.3.3 Drying chamber
4.3.4 Powder separators
4.4 Drying of droplets
4.4.1 Fundamentals of droplet drying
4.4.2 Drying kinetics
4.4.3 Residence time
4.5 Mass and heat balances over a spray drier
4.5.1 Overall mass balance
4.5.2 Overall heat balance
4.6 Drier efficiency
4.6.1 Thermal efficiency
4.6.2 Evaporative efficiency
4.6.3 Volumetric evaporative capacity
4.7 Powder characterization
4.7.1 Particle micro-structure
4.7.2 Particle morphology
4.7.3 Physical and functional properties of powder
4.7.4 Drying parameters
4.8 Spray drying of various food products
4.8.1 Dairy powders
4.8.2 Micro-encapsulated powders
4.8.3 Sugar-rich products
4.8.4 Egg
4.8.5 Enzymes
4.9 Concluding remarks
4.10 Notation
References
5 Low-pressure superheated steam drying of food products
5.1 Introduction
5.2 Basic principles of superheated steam drying
5.3 Low-pressure superheated steam drying offoods and biomaterials
5.4 Some advances in LPSSD of foods and biomaterials
5.5 Mathematical modeling of LPSSD of foods and biomaterials
5.6 Concluding remarks
5.7 Notation
References
6 Heat pump-assisted drying
6.1 Introduction
6.2 Classification of heat pump driers
6.3 Fundamentals of heat pump driers
6.4 Heat and mass transfer mechanisms
6.5 Optimum use of heat pumps in drying systems
6.6 Innovative heat pump drying systems
6.6.1 Multi-stage compression heat pump drying
6.6.2 Cascade heat pump drying systems
6.6.3 Heat pump drying systems with multiple evaporators in series and in parallel
6.6.4 Vapor absorption heat pump drier
6.7 Closing remarks
6.8 Notation
References
7 Freeze and vacuum drying of foods
7.1 Introduction
7.2 States of water
7.3 Food and air properties in relation to vacuum and freeze-drying
7.4 Heat transfer mechanisms at low pressures
7.5 Vacuum drying: principles and dehydration models
7.6 Freeze drying: principles and dehydration models
7.7 Illustrative example
7.8 Advances in vacuum and freeze drying offoods
7.9 Closure
7.10 Notation
References
8 Post-drying aspects for meat and horticultural products
8.1 Introduction
8.2 State diagram and stability concepts of dried products
8.3 Controlling quality attributes
8.3.1 Microbial quality
8.3.2 Chemical changes and quality
8.3.3 Physical changes and quality
8.3.4 Vitamins retention
8.4 Conclusion
References
9 Food drier process control
9.1 Introduction - why process control?
9.1.1 Disturbance variables
9.1.2 Control benefits
9.1.3 Examples
9.1.4 Chapter organization
9.2 What to control (manipulated and controlled variables)
9.2.1 Controlled variables
9.2.2 Manipulated variables
9.3 Where to control (control strategy)
9.3.1 Plant-wide control strategy configuration
9.3.2 Common loops and examples
9.4 When to control (control philosophy)
9.4.1 After something happens - feedback control
9.4.2 As something happens - feed-forward/predictive control
9.5 How to control (fundamental control methods)
9.5.1 PID feedback control and tuning
9.6 How to do advanced control (advanced control methods)
9.6.1 Model predictive control (MPC)
9.6.2 Adaptive control
9.6.3 Artificial intelligence in control
References
10 Fire and explosion protection in food driers
10.1 Introduction - thermal hazards in driers
10.1.1 Conditions for an explosion to occur
10.1.2 How serious is the problem?
10.1.3 What affects the degree of violence of a dust explosion?
10.1.4 How to reduce the risk of dust explosion
10.2 A practical example: milk powder plant safety
10.2.1 Fires
10.2.2 Explosion protection
10.3 Testing for various explosion parameters
10.4 The human factors
10.5 Concluding remarks
References
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