Spray drying is a well-established method for transforming liquid materials into dry powder form. Widely used in the food and pharmaceutical industries, this technology produces high quality powders with low moisture content, resulting in a wide range of shelf stable food and other biologically significant products. Encapsulation technology for bioactive compounds has gained momentum in the last few decades and a series of valuable food compounds, namely flavours, carotenoids and microbial cells have been successfully encapsulated using spray drying.
Spray Drying Technique for Food Ingredient Encapsulation provides an insight into the engineering aspects of the spray drying process in relation to the encapsulation of food ingredients, choice of wall materials, and an overview of the various food ingredients encapsulated using spray drying. The book also throws light upon the recent advancements in the field of encapsulation by spray drying, i.e., nanospray dryers for production of nanocapsules and computational fluid dynamics (CFD) modeling.
Addressing the basics of the technology and its applications, the book will be a reference for scientists, engineers and product developers in the industry.
Autorentext
Dr C. Anandharamakrishnan is Principal Scientist of the Food Engineering Department, CSIR-Central Food Technological Research Institute, Mysore, India.
Padma Ishwarya S. is Research Fellow of the Food Engineering Department, CSIR-Central Food Technological Research Institute, Mysore, India.
Inhalt
About the authors xiv
Preface xv
Acknowledgments xvi
1 Introduction to spray drying 1
1.1 Introduction 1
1.2 Stage 1: Atomization 2
1.2.1 Principle of atomization 3
1.2.2 Classification of atomizers 4
1.2.2.1 Rotary atomizers 4
1.2.2.2 Pressure nozzle (or hydraulic) atomizer 6
1.2.2.3 Two-fluid nozzle atomizer 7
1.2.2.4 Ultrasonic atomizers 8
1.2.2.5 Electrohydrodynamic atomizers 9
1.3 Stage 2: Spray-air contact 11
1.4 Stage 3: Evaporation of moisture 13
1.5 Stage 4: Particle separation 15
1.5.1 Cyclone separator 15
1.5.2 Bag filter 15
1.5.3 Electrostatic precipitator 17
1.6 Morphology of spray dried particles 17
1.6.1 Skin-forming morphology with hollow internal structure 19
1.6.2 Blow-hole formation 20
1.6.3 Agglomerate 21
1.6.4 Formation of dented structure and presence of small particles within large particles 21
1.7 Spray-drying process parameters and their influence on product quality 22
1.7.1 Atomization parameters 22
1.7.1.1 Atomization pressure 22
1.7.1.2 Feed flow rate 23
1.7.1.3 Feed viscosity 23
1.7.1.4 Feed surface tension 23
1.8 Parameters of spray-air contact and evaporation 24
1.8.1 Aspirator flow rate (or speed) 24
1.8.2 Inlet temperature 24
1.8.3 Outlet temperature 25
1.8.4 Glass transition temperature (Tg) 27
1.8.5 Residence time of particles in the spray chamber 27
1.9 Types of spray dryer 27
1.9.1 Open cycle spray dryer 28
1.9.2 Closed cycle spray dryer 28
1.9.3 Semi-closed cycle spray dryer 28
1.9.4 Single-stage spray dryer 29
1.9.5 Two-stage spray dryer 29
1.9.6 Short-form 30
1.9.7 Tall-form 30
1.10 Applications and advantages of spray drying 31
References 33
2 Introduction to encapsulation of food ingredients 37
2.1 Introduction 37
2.2 Encapsulation of food ingredients 37
2.3 The core and wall for encapsulation 40
2.3.1 Carbohydrates 42
2.3.2 Proteins 42
2.3.3 Lipids 43
2.4 Encapsulation techniques 43
2.4.1 Chemical encapsulation processes 44
2.4.1.1 Coacervation 44
2.4.1.2 Inclusion complexation 45
2.4.1.3 Liposome entrapment 47
2.4.2 Mechanical or physical encapsulation processes 48
2.4.2.1 Emulsification 48
2.4.2.2 Spray chilling, spray cooling and fluidized bed drying 50
2.4.2.3 Freeze drying 50
2.4.2.4 Extrusion 52
2.4.2.5 Electrohydrodynamic technique for microencapsulation: electrospraying and electrospinning 53
2.4.2.6 Spray drying 54
2.5 The lexicon of encapsulation 59
References 60
3 Spray drying for encapsulation 65
3.1 Introduction 65
3.2 Principle of encapsulation by spray drying 65
3.3 Process steps and parameters of encapsulation by spray drying 67
3.3.1 Emulsion formation 67
3.3.1.1 Rationale of emulsification step 67
3.3.1.2 Emulsion parameters influencing encapsulation efficiency 68
3.3.2 Spray drying of emulsion 70
3.3.2.1 Atomization of the emulsion and influencing parameters 70
3.3.2.2 Drying of the emulsion droplets and influencing parameters 71
3.4 Food ingredients encapsulated by spray drying 71
3.4.1 Microorganisms 72
3.4.2 Flavors 72
3.4.3 Bioactive food components 73
References 74
4 Selection of wall material for encapsulation by spray drying 77
4.1 Introduction 77
4.2 Characteristics of wall materials for encapsulation by spray drying 77
4.2.1 Solubility 77
4.2.2 Emulsification property 78
4.2.3 Film-forming ability 78
4.2.4 Viscosity 78
4.2.5 Glass transition 79
4.2.6 Degree of crystallinity 79
4.3 Approaches to choosing wall materials for encapsulation 80
4.3.1 Estimation of drying kinetics and drying curve analysis for wall material selection 81
4.3.1.1 Isothermal drying method 81
4.3.1.2 Estimation of drying kinetics under simulated conditions of spray drying 82
4.3.2 Estimation of emulsification capacity 84
4.3.3 Analysis of viscosity and rheological characteristics of wall material dispersion 85
4.3.4 Determination of thermal properties of wall materials 86
4.4 Commonly used wall materials for encapsulation of food ingredients by spray drying 88
4.4.1 Gum Arabic 88
4.4.2 Maltodextrin 89
4.4.3 Whey protein (concentrate or isolate) 91
4.4.4 Gelatin 91
4.4.5 Sodium caseinate 92
4.4.6 Modified starches 92
4.4.7 Chitosan 93
References 98
5 Encapsulation of probiotics by spray drying 101
5.1 Introduction 101
5.2 Definition of probiotics and significance of probiotics encapsulation 101
5.3 Probiotic characteristics of importance to spray drying encapsulation 103
5.4 Criteria to decide suitability of wall material for encapsulation of probiotics 104
5.5 Selection of spray drying process parameters 106
5.5.1 Effect of atomization on probiotic cell viability 107
5.5.2 Effect of spray drying process conditions on probiotic cell survival 108
5.5.2.1 Thermal effect of spray drying process on cell viability 109
5.5.2.2 Dehydration effect of spray drying process on cell viability 112
5.6 Stability of spray dried probiotic microencapsulates to gastric environment 115
References 122
6 Encapsulation of flavors and specialty oils 126
6.1 Introduction 126
6.2 Selective diffusion theory and mechanisms of volatile retention during spray drying 127
6.3 Performance parameters of flavor encapsulation by spray drying 132
6.3.1 Encapsulation efficiency 133
6.3.1.1 Total oil analysis 133
6.3.1.2 Surface oil analysis 134
6.3.2 Lipid oxidation 134
6.3.2.1 Peroxide value determination 134
6.3.2.2 Active oxygen determination 135
6.3.3 Morphology and particle size 135
6.4 Factors influencing encapsulation of flavors and oils by spray drying 137
6.4.1 Emulsion-related factors 1…