COPYRIGHTED MATERIAL. Contents. xiv xv xvi. About the authors Preface Acknowledgments

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1 About the authors Preface Acknowledgments 1 Introduction to spray drying Introduction Stage 1: Atomization Principle of atomization Classification of atomizers Rotary atomizers Pressure nozzle (or hydraulic) atomizer Two fluid nozzle atomizer Ultrasonic atomizers Electrohydrodynamic atomizers Stage 2: Spray air contact Stage 3: Evaporation of moisture Stage 4: Particle separation Cyclone separator Bag filter Electrostatic precipitator Morphology of spray dried particles Skin forming morphology with hollow internal structure Blow hole formation Agglomerate Formation of dented structure and presence of small particles within large particles Spray drying process parameters and their influence on product quality Atomization parameters Atomization pressure Feed flow rate Feed viscosity Feed surface tension Parameters of spray air contact and evaporation Aspirator flow rate (or speed) Inlet temperature Outlet temperature Glass transition temperature (T g ) Residence time of particles in the spray chamber Types of spray dryer Open cycle spray dryer Closed cycle spray dryer 28 COPYRIGHTED MATERIAL xiv xv xvi

2 viii Contents Semi closed cycle spray dryer Single stage spray dryer Two stage spray dryer Short form Tall form Applications and advantages of spray drying 31 References 33 2 Introduction to encapsulation of food ingredients Introduction Encapsulation of food ingredients The core and wall for encapsulation Carbohydrates Proteins Lipids Encapsulation techniques Chemical encapsulation processes Coacervation Inclusion complexation Liposome entrapment Mechanical or physical encapsulation processes Emulsification Spray chilling, spray cooling and fluidized bed drying Freeze drying Extrusion Electrohydrodynamic technique for microencapsulation: electrospraying and electrospinning Spray drying The lexicon of encapsulation 59 References 60 3 Spray drying for encapsulation Introduction Principle of encapsulation by spray drying Process steps and parameters of encapsulation by spray drying Emulsion formation Rationale of emulsification step Emulsion parameters influencing encapsulation efficiency Spray drying of emulsion Atomization of the emulsion and influencing parameters Drying of the emulsion droplets and influencing parameters Food ingredients encapsulated by spray drying Microorganisms Flavors Bioactive food components 73 References 74

3 ix 4 Selection of wall material for encapsulation by spray drying Introduction Characteristics of wall materials for encapsulation by spray drying Solubility Emulsification property Film forming ability Viscosity Glass transition Degree of crystallinity Approaches to choosing wall materials for encapsulation Estimation of drying kinetics and drying curve analysis for wall material selection Isothermal drying method Estimation of drying kinetics under simulated conditions of spray drying Estimation of emulsification capacity Analysis of viscosity and rheological characteristics of wall material dispersion Determination of thermal properties of wall materials Commonly used wall materials for encapsulation of food ingredients by spray drying Gum Arabic Maltodextrin Whey protein (concentrate or isolate) Gelatin Sodium caseinate Modified starches Chitosan 93 References 98 5 Encapsulation of probiotics by spray drying Introduction Definition of probiotics and significance of probiotics encapsulation Probiotic characteristics of importance to spray drying encapsulation Criteria to decide suitability of wall material for encapsulation of probiotics Selection of spray drying process parameters Effect of atomization on probiotic cell viability Effect of spray drying process conditions on probiotic cell survival Thermal effect of spray drying process on cell viability Dehydration effect of spray drying process on cell viability Stability of spray dried probiotic microencapsulates to gastric environment 115 References Encapsulation of flavors and specialty oils Introduction Selective diffusion theory and mechanisms of volatile retention during spray drying 127

4 x Contents 6.3 Performance parameters of flavor encapsulation by spray drying Encapsulation efficiency Total oil analysis Surface oil analysis Lipid oxidation Peroxide value determination Active oxygen determination Morphology and particle size Factors influencing encapsulation of flavors and oils by spray drying Emulsion related factors Wall material Core Spray drying related factors Atomization factors Inlet and exit air temperatures Feed temperature 145 References Encapsulation of bioactive ingredients by spray drying Introduction Spray drying for encapsulation of polyphenols Polyphenols and their functional properties Rationale for encapsulation of polyphenols Influence of core nature on encapsulation efficiency Influence of wall material selection and spray drying process parameters on polyphenolic core retention Spray drying encapsulation of vitamins The functional benefits of vitamins Vitamin stability and rationale for encapsulation of vitamins Influence of wall material and feed composition on vitamin encapsulation Influence of spray drying process parameters on vitamin encapsulation Spray drying encapsulation of carotenoids Carotenoids and their functional significance Rationale for encapsulation of carotenoids Effect of wall material selection and feed composition on encapsulation of carotenoids Effect of spray drying process conditions on encapsulation of carotenoids 167 References Spray drying for nanoencapsulation of food components Introduction Introduction to food nanoparticles and nanoencapsulation Nano spray dryer Operation principle of nano spray dryer Piezo electric driven vibrating mesh atomization 183

5 xi Heating mode, hot air flow pattern in and configuration of spray chamber Product separation by electrostatic precipitator Nanoencapsulation of food bioactive compounds by nano spray dryer Analytical methods to characterize nanoencapsulates in foods Electron microscopy Scanning electron microscopy Transmission electron microscopy Atomic force microscopy Atmospheric scanning electron microscopy Quantification of nanoparticles size and mass by electron microscopy 193 References Functional properties of spray dried encapsulates Introduction Controlled release of encapsulated bioactive compounds Controlled release by dissolution Controlled release by diffusion Masking of off taste by spray drying encapsulation Improvement in stability of encapsulated bioactive compounds 202 References Analysis of spray dried encapsulates Introduction Analysis of physical characteristics of spray dried encapsulates Moisture content Particle size Analysis of the efficiency of spray drying encapsulation process Estimation of encapsulation efficiency Encapsulation efficiency of specialty oils Encapsulation efficiency of vitamins and polyphenolic compounds Encapsulation efficiency of flavors and other volatile compounds Encapsulation efficiency of probiotic cells Analysis of the stability of spray dried microencapsulates Analysis of probiotic cell stability under simulated in vitro gastrointestinal conditions Analysis of oxidative stability for lipophilic core compounds Estimation of peroxide value by spectrophotometry method Rancimat method for estimation of peroxide value Gas chromatography method for analysis of oxidative stability Analysis of the functional properties of spray dried encapsulates Study of core release from microencapsulates Taste masking effects 221 References 222

6 xii Contents 11 Modeling approach for spray drying and encapsulation applications Introduction Computational fluid dynamics modeling Conservation of mass equation Conservation of momentum equation Conservation of energy equation Modeling of spray drying process a theoretical perspective Atomization Boundary conditions for atomization models Spray air contact Reference frames Turbulence models Droplet/particle trajectory Droplet temperature Droplet residence time Particle impact position Droplet drying and particle formation Modeling of core release from encapsulates 245 References Synergistic spray drying techniques for encapsulation Introduction Spray fluidized bed coating for encapsulation Theory of fluidization Fluid bed encapsulation process steps and influential factors Atomization Droplet particle interactions Drying of coating material on particle surface Food ingredient applications of spray fluidized bed coating Challenges associated with spray fluidized bed coating Recent advancements in spray fluidized bed coating Spray-freeze-drying for encapsulation Spray freezing Spray freezing into vapor (SFV) Spray freezing into vapor over liquid (SFV/L) Spray freezing into liquid (SFL) Freeze drying Conventional freeze drying Atmospheric freeze drying Factors affecting the encapsulation efficiency of SFD process 271 References 273

7 xiii 13 Industrial relevance and commercial applications of spray dried active food encapsulates Introduction Applications of spray dried encapsulates in the food industries Confectionery industry Bakery industry Other product categories Cost analysis of the spray drying encapsulated active ingredient Major industry players producing spray dried encapsulated food ingredients Symrise International Flavors & Fragrances (IFF) Firmenich Givaudan Takasago International Corporation TasteTech Kievit Synthite Challenges and future scope of the spray drying encapsulation of food ingredients 283 References 284 Index 285