Agro-Product Processing Technology: Principles and Practice

420 Pages·2020·37.614 MB·English

by  B. K. Bala

AGRO­PRODUCT PROCESSING
TECHNOLOGY
PRINCIPLES AND PRACTICE
B. K. Bala
Agro-Product Processing
Technology

Agro-Product Processing
Technology
Principles and Practice
B. K. Bala
Bangabandhu Sheikh Mujibur Rahman Science and Technology University
Gopalganj, Bangladesh
First edition published 2020
by CRC Press
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ISBN: 978-1-138-59668-9 (hbk)
ISBN: 978-0-429-48750-7 (ebk)
Typeset in Times
by Lumina Datamatics Limited
Contents
Foreword ..........................................................................................................................................xv
Preface............................................................................................................................................xvii
Author .............................................................................................................................................xix
Chapter 1 Introduction ..................................................................................................................1
1.1 Introduction .........................................................................................................1
1.2 Impotence of Postharvest Technology .................................................................2
1.3 Importance of Postharvest Losses .......................................................................2
1.4 Postharvest Technology .......................................................................................3
References ....................................................................................................................5
Chapter 2 Physical, Thermal, and Chemical Properties of Food and Biological Materials .........7
2.1 Introduction .........................................................................................................7
2.2 Physical Properties ..............................................................................................7
2.2.1 Physical Dimensions ................................................................................7
2.2.2 1000-Grain Weight ..................................................................................7
2.2.3 Bulk Density ............................................................................................8
2.2.4 Shrinkage .................................................................................................8
2.2.5 Friction ....................................................................................................9
2.2.5.1 Angle of Internal Friction and Angle of Repose ......................9
2.2.5.2 Coefficient of Friction .............................................................10
2.3 Thermal Properties ............................................................................................11
2.3.1 Specific Heat ..........................................................................................11
2.3.2 Thermal Conductivity ...........................................................................13
2.3.2.1 Theory .....................................................................................13
2.3.2.2 Apparatus and Measurement ..................................................14
2.3.3 Latent Heat of Vaporization ..................................................................15
2.3.3.1 Determination of Latent Heat of Vaporization .......................16
2.3.4 Heat Transfer Coefficient of Product Bed .............................................18
2.3.4.1 Dimensional Analysis .............................................................19
2.3.4.2 Comparison of Theory and Experiment .................................19
2.3.4.3 Theory .....................................................................................20
2.3.4.4 Determination of Volumetric Heat Transfer Coefficient ........22
2.4 Chemical Properties ..........................................................................................24
2.4.1 Starch .....................................................................................................24
2.4.2 Protein ...................................................................................................24
2.4.3 Fat ..........................................................................................................24
2.4.4 Vitamin ..................................................................................................24
Key to Symbols ..........................................................................................................24
Exercises .....................................................................................................................26
References ..................................................................................................................27
v
vi Contents
Chapter 3 Cleaning, Grading, and Sorting .................................................................................29
3.1 Grade Factor ....................................................................................................29
3.2 Washing ...........................................................................................................30
3.3 Sorting Fruits and Vegetables ..........................................................................30
3.4 Sorting Grain ...................................................................................................30
3.5 Spiral Separator ...............................................................................................32
3.6 Indent Cylinder Separator ...............................................................................33
3.7 Color Separator ................................................................................................33
3.8 Centrifugal Separation ....................................................................................34
3.8.1 Stokes’ Equation .................................................................................34
3.9 The Centrifuge.................................................................................................35
3.10 The Cream Separator .......................................................................................35
3.11 Cyclone Separator ............................................................................................36
3.12 Machine Vision................................................................................................39
3.12.1 Image Acquisition .............................................................................39
3.12.1.1 Computer Vision System ..................................................39
3.12.1.2 Ultrasound and Infrared ...................................................40
3.12.1.3 Tomographic Imaging ......................................................40
3.12.2 Preprocessing ....................................................................................40
3.12.3 Segmentation .....................................................................................41
3.12.4 Feature Extraction .............................................................................42
3.12.4.1 Color Features ..................................................................42
3.12.4.2 Morphological Features....................................................43
3.12.4.3 Texture Features ...............................................................43
3.12.5 Classification .....................................................................................44
Bibliography ...............................................................................................................45
Chapter 4 Psychrometry ..............................................................................................................47
4.1 Introduction .....................................................................................................47
4.2 Psychrometric Terms .......................................................................................47
4.2.1 Humidity Ratio ..................................................................................48
4.2.2 Relative Humidity .............................................................................48
4.2.3 Specific Volume ................................................................................49
4.2.4 Vapor Pressure ..................................................................................49
4.2.5 Dry-Bulb Temperature ......................................................................49
4.2.6 Dew Point Temperature.....................................................................49
4.2.7 Wet-Bulb Temperature ......................................................................49
4.2.8 Enthalpy ............................................................................................50
4.2.9 Adiabatic Wet-Bulb Temperature ......................................................51
4.2.10 Psychrometric Wet-Bulb Temperature ..............................................52
4.3 Construction of Psychrometric Chart ..............................................................54
4.4 Use of Psychrometric Chart ............................................................................54
4.4.1 Sensible Heating and Cooling ...........................................................55
4.4.2 Heating with Humidification .............................................................55
4.4.3 Cooling with Humidification ............................................................56
4.4.4 Cooling with Dehumidification.........................................................56
4.4.5 Drying ...............................................................................................57
4.4.6 Mixing of Airstreams .......................................................................59
Contents vii
4.4.7 Heat Addition with Air Mixing ..........................................................61
4.4.8 Drying with Recirculation ..................................................................62
Key to Symbols ..........................................................................................................66
Exercises .....................................................................................................................68
Bibliography ...............................................................................................................68
Chapter 5 Drying of Agro Products ............................................................................................69
5.1 Principles of Drying ..........................................................................................69
5.2 Importance of Drying ........................................................................................69
5.3 Moisture Content ...............................................................................................70
5.3.1 Moisture Content Representation ..........................................................70
5.3.2 Determination of Moisture Content ......................................................72
5.3.2.1 Direct Methods .......................................................................73
5.3.2.2 Indirect Methods .....................................................................75
5.4 Equilibrium Moisture Content ..........................................................................76
5.4.1 Determination of Static Equilibrium Moisture Content ........................77
5.4.2 Static Equilibrium Moisture Content Models .......................................77
5.5 Mechanism of Drying........................................................................................82
5.6 Thin-Layer Drying ............................................................................................84
5.6.1 Thin-Layer Drying Equations ...............................................................84
5.6.1.1 Empirical Drying Equations ...................................................84
5.6.1.2 Theoretical Drying Equations ................................................84
5.6.1.3 Semi-Theoretical Drying Equations .......................................85
5.6.2 Drying Rate ...........................................................................................87
5.6.3 Drying Parameters .................................................................................87
5.6.4 Drying Rate Constant and Diffusion Coefficient ..................................88
5.6.4.1 Drying Rate Constant .............................................................88
5.6.5 Half Response Time ..............................................................................91
5.7 Deep-Bed Drying ..............................................................................................92
5.7.1 Logarithmic Model ................................................................................92
5.7.2 Partial Differential Equation Model ......................................................98
5.7.2.1 Method of Solution ...............................................................102
5.7.2.2 Comparisons of Simulated and Observed Results ................103
5.8 Fluidized Bed Drying Model ..........................................................................103
5.8.1 Heat Balance Equation ........................................................................104
5.8.2 Drying Rate Equation ..........................................................................104
5.8.3 Mass Balance Equation .......................................................................105
5.9 Agro-Product Drying Systems ........................................................................106
5.9.1 Solar Drying Systems ..........................................................................106
5.9.1.1 Solar Dryers ..........................................................................106
5.9.2 Batch Drying Systems .........................................................................110
5.9.2.1 Flatbed Dryer ........................................................................111
5.9.3 Continuous Flow Drying Systems .......................................................113
5.9.3.1 Cross-Flow Dryer .................................................................113
5.9.3.2 Cross-Flow Batch Dryer .......................................................113
5.9.3.3 Concurrent Flow Dryer .........................................................114
5.9.3.4 Counterflow Dryer ................................................................114
5.9.3.5 Mixed-Flow Dryer ................................................................116
viii Contents
5.10 Safe Temperature for Drying Grain ..............................................................117
5.11 Selection of Dryers ........................................................................................117
Key to Symbols ........................................................................................................118
Exercises ...................................................................................................................119
Bibliography .............................................................................................................120
Chapter 6 Parboiling of Rice ....................................................................................................123
6.1 Introduction ...................................................................................................123
6.2 Principles of Parboiling .................................................................................124
6.3 Soaking ..........................................................................................................124
6.3.1 Kinetics of Soaking ...........................................................................126
6.3.2 Finite Element Modeling of Soaking of Water by Paddy ..................132
6.3.3 Half Response Time ..........................................................................137
6.3.4 Kinetics of Water Diffusion and Starch Gelatinization ....................137
6.4 Steaming ........................................................................................................140
6.5 Drying ............................................................................................................140
6.6 Effect of Parboiling on Milling, Nutritional, and Cooking Qualities
of Rice ...........................................................................................................141
6.7 Parboiling Methods .......................................................................................142
6.7.1 Traditional Methods ..........................................................................142
6.7.1.1 Single Stage Parboiling ......................................................142
6.7.1.2 Double Stage Parboiling .....................................................142
6.7.2 Modern Methods ...............................................................................142
6.7.2.1 CFTRI (Central Food Technological Research
Industries) Method .............................................................143
6.7.2.2 Jadavpur University Method ..............................................143
6.7.2.3 Malek Process ....................................................................143
6.7.2.4 Schule Process ....................................................................143
6.7.2.5 Crystal Rice Process ..........................................................144
6.7.2.6 Rice Conversion Process ....................................................144
6.7.2.7 Avorio Process ....................................................................144
6.7.3 Estimation of Heat Required for Parboiling ......................................144
6.7.3.1 Soaking Operation..............................................................144
6.7.3.2 Steaming Operation............................................................144
6.7.3.3 Drying Operation ...............................................................145
Exercises ...................................................................................................................159
Bibliography .............................................................................................................160
Chapter 7 Milling of Rice and Wheat .......................................................................................163
7.1 Introduction ...................................................................................................163
7.2 Rice Milling ..................................................................................................163
7.3 Traditional Methods ......................................................................................163
7.3.1 Home Pounding .................................................................................163
7.3.2 Huller Mills .......................................................................................164
7.3.3 Sheller Mills ......................................................................................164
7.3.4 Rubber Roll Sheller Mills ..................................................................164
7.4 The Modern Rice Milling Process ................................................................165
Contents ix
7.5 Modern Rice Milling Machinery ....................................................................167
7.5.1 Paddy Cleaner ......................................................................................167
7.5.2 Stoner ...................................................................................................167
7.5.3 Rubber Roll Sheller .............................................................................167
7.5.4 Paddy Separator ...................................................................................169
7.5.5 Whitening or Polishing........................................................................171
7.5.5.1 Cone-Type Polisher ...............................................................171
7.5.5.2 Horizontal Abrasive-Type Polisher .......................................172
7.5.5.3 Friction-Type Polisher ...........................................................172
7.5.6 Bran and Polished Rice Separator .......................................................173
7.5.7 Rice Grader .........................................................................................173
7.5.8 Rice Mixing .........................................................................................174
7.6 Wheat Milling .................................................................................................174
7.6.1 Conditioning/Hydrothermal Treatment ...............................................174
7.6.2 Milling .................................................................................................174
7.6.3 Storage of Finished Products ...............................................................175
7.7 Size Characteristics .........................................................................................175
7.7.1 Sieve .....................................................................................................175
7.7.2 Fineness Modulus ................................................................................176
7.7.3 Energy Requirements ..........................................................................177
Bibliography .............................................................................................................179
Chapter 8 By-Product Utilization .............................................................................................181
8.1 Introduction .....................................................................................................181
8.2 Fuels and Combustion .....................................................................................181
8.2.1 Furnaces ..............................................................................................182
8.3 Pyrolysis and Gasification ...............................................................................183
8.3.1 Pyrolysis (Destructive Distillation) and Gasification ..........................183
8.3.2 Types of Gasifiers ................................................................................184
8.3.2.1 Countercurrent Moving Bed Gasifiers ..................................185
8.3.2.2 Concurrent Moving Bed Gasifiers ........................................185
8.3.2.3 Crosscurrent Moving Bed Gasifiers .....................................185
8.3.2.4 Fluidized Bed Gasifiers ........................................................185
8.3.3 Gasification Process ............................................................................185
8.3.3.1 Oxidation ..............................................................................186
8.3.3.2 Reduction ..............................................................................186
8.3.3.3 Drying ...................................................................................186
8.3.4 Gasifier Units .......................................................................................186
8.4 Liquefaction .....................................................................................................187
8.5 Hydrolysis Followed by Fermentation .............................................................189
8.6 Biochar Production and Utilization .................................................................190
8.6.1 Biochar Carbonizer .............................................................................190
8.6.2 Types of Carbonizers ...........................................................................191
8.6.2.1 Application............................................................................192
8.7 Rice Husk Pelletizing and Briquetting ............................................................192
8.7.1 Need for Briquetting ............................................................................193
8.7.2 Principle and Technology ....................................................................193