Spray Drying Techniques for Food Ingredient Encapsulation

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.

• About the authors xivPreface xvAcknowledgments xvi1 Introduction to spray drying 11.1 Introduction 11.2 Stage 1: Atomization 21.2.1 Principle of atomization 31.2.2 Classification of atomizers 41.2.2.1 Rotary atomizers 41.2.2.2 Pressure nozzle (or hydraulic) atomizer 61.2.2.3 Two-fluid nozzle atomizer 71.2.2.4 Ultrasonic atomizers 81.2.2.5 Electrohydrodynamic atomizers 91.3 Stage 2: Spray-air contact 111.4 Stage 3: Evaporation of moisture 131.5 Stage 4: Particle separation 151.5.1 Cyclone separator 151.5.2 Bag filter 151.5.3 Electrostatic precipitator 171.6 Morphology of spray dried particles 171.6.1 Skin-forming morphology with hollow internal structure 191.6.2 Blow-hole formation 201.6.3 Agglomerate 211.6.4 Formation of dented structure and presence of small particles within large particles 211.7 Spray-drying process parameters and their influence on product quality 221.7.1 Atomization parameters 221.7.1.1 Atomization pressure 221.7.1.2 Feed flow rate 231.7.1.3 Feed viscosity 231.7.1.4 Feed surface tension 231.8 Parameters of spray-air contact and evaporation 241.8.1 Aspirator flow rate (or speed) 241.8.2 Inlet temperature 241.8.3 Outlet temperature 251.8.4 Glass transition temperature (Tg) 271.8.5 Residence time of particles in the spray chamber 271.9 Types of spray dryer 271.9.1 Open cycle spray dryer 281.9.2 Closed cycle spray dryer 281.9.3 Semi-closed cycle spray dryer 281.9.4 Single-stage spray dryer 291.9.5 Two-stage spray dryer 291.9.6 Short-form 301.9.7 Tall-form 301.10 Applications and advantages of spray drying 31References 332 Introduction to encapsulation of food ingredients 372.1 Introduction 372.2 Encapsulation of food ingredients 372.3 The core and wall for encapsulation 402.3.1 Carbohydrates 422.3.2 Proteins 422.3.3 Lipids 432.4 Encapsulation techniques 432.4.1 Chemical encapsulation processes 442.4.1.1 Coacervation 442.4.1.2 Inclusion complexation 452.4.1.3 Liposome entrapment 472.4.2 Mechanical or physical encapsulation processes 482.4.2.1 Emulsification 482.4.2.2 Spray chilling, spray cooling and fluidized bed drying 502.4.2.3 Freeze drying 502.4.2.4 Extrusion 522.4.2.5 Electrohydrodynamic technique for microencapsulation: electrospraying and electrospinning 532.4.2.6 Spray drying 542.5 The lexicon of encapsulation 59References 603 Spray drying for encapsulation 653.1 Introduction 653.2 Principle of encapsulation by spray drying 653.3 Process steps and parameters of encapsulation by spray drying 673.3.1 Emulsion formation 673.3.1.1 Rationale of emulsification step 673.3.1.2 Emulsion parameters influencing encapsulation efficiency 683.3.2 Spray drying of emulsion 703.3.2.1 Atomization of the emulsion and influencing parameters 703.3.2.2 Drying of the emulsion droplets and influencing parameters 713.4 Food ingredients encapsulated by spray drying 713.4.1 Microorganisms 723.4.2 Flavors 723.4.3 Bioactive food components 73References 744 Selection of wall material for encapsulation by spray drying 774.1 Introduction 774.2 Characteristics of wall materials for encapsulation by spray drying 774.2.1 Solubility 774.2.2 Emulsification property 784.2.3 Film-forming ability 784.2.4 Viscosity 784.2.5 Glass transition 794.2.6 Degree of crystallinity 794.3 Approaches to choosing wall materials for encapsulation 804.3.1 Estimation of drying kinetics and drying curve analysis for wall material selection 814.3.1.1 Isothermal drying method 814.3.1.2 Estimation of drying kinetics under simulated conditions of spray drying 824.3.2 Estimation of emulsification capacity 844.3.3 Analysis of viscosity and rheological characteristics of wall material dispersion 854.3.4 Determination of thermal properties of wall materials 864.4 Commonly used wall materials for encapsulation of food ingredients by spray drying 884.4.1 Gum Arabic 884.4.2 Maltodextrin 894.4.3 Whey protein (concentrate or isolate) 914.4.4 Gelatin 914.4.5 Sodium caseinate 924.4.6 Modified starches 924.4.7 Chitosan 93References 985 Encapsulation of probiotics by spray drying 1015.1 Introduction 1015.2 Definition of probiotics and significance of probiotics encapsulation 1015.3 Probiotic characteristics of importance to spray drying encapsulation 1035.4 Criteria to decide suitability of wall material for encapsulation of probiotics 1045.5 Selection of spray drying process parameters 1065.5.1 Effect of atomization on probiotic cell viability 1075.5.2 Effect of spray drying process conditions on probiotic cell survival 1085.5.2.1 Thermal effect of spray drying process on cell viability 1095.5.2.2 Dehydration effect of spray drying process on cell viability 1125.6 Stability of spray dried probiotic microencapsulates to gastric environment 115References 1226 Encapsulation of flavors and specialty oils 1266.1 Introduction 1266.2 Selective diffusion theory and mechanisms of volatile retention during spray drying 1276.3 Performance parameters of flavor encapsulation by spray drying 1326.3.1 Encapsulation efficiency 1336.3.1.1 Total oil analysis 1336.3.1.2 Surface oil analysis 1346.3.2 Lipid oxidation 1346.3.2.1 Peroxide value determination 1346.3.2.2 Active oxygen determination 1356.3.3 Morphology and particle size 1356.4 Factors influencing encapsulation of flavors and oils by spray drying 1376.4.1 Emulsion-related factors 1376.4.1.1 Wall material 1376.4.1.2 Core 1406.4.2 Spray drying-related factors 1426.4.2.1 Atomization factors 1426.4.2.2 Inlet and exit air temperatures 1436.4.2.3 Feed temperature 145References 1537 Encapsulation of bioactive ingredients by spray drying 1567.1 Introduction 1567.2 Spray drying for encapsulation of polyphenols 1567.2.1 Polyphenols and their functional properties 1567.2.2 Rationale for encapsulation of polyphenols 1577.2.3 Influence of core nature on encapsulation efficiency 1577.2.4 Influence of wall material selection and spray dryingprocess parameters on polyphenolic core retention 1577.3 Spray drying encapsulation of vitamins 1617.3.1 The functional benefits of vitamins 1617.3.2 Vitamin stability and rationale for encapsulation of vitamins 1617.3.3 Influence of wall material and feed composition on vitamin encapsulation 1627.3.4 Influence of spray drying process parameters on vitamin encapsulation 1637.4 Spray drying encapsulation of carotenoids 1637.4.1 Carotenoids and their functional significance 1637.4.2 Rationale for encapsulation of carotenoids 1657.4.3 Effect of wall material selection and feed composition on encapsulation of carotenoids 1657.4.4 Effect of spray drying process conditions on encapsulation of carotenoids 167References 1768 Spray drying for nanoencapsulation of food components 1808.1 Introduction 1808.2 Introduction to food nanoparticles and nanoencapsulation 1818.3 Nano spray dryer 1838.3.1 Operation principle of nano spray dryer 1838.3.1.1 Piezo-electric driven vibrating mesh atomization 1838.3.1.2 Heating mode, hot air flow pattern in and configuration of spray chamber 1848.3.1.3 Product separation by electrostatic precipitator 1868.4 Nanoencapsulation of food bioactive compounds by nano spray dryer 1888.5 Analytical methods to characterize nanoencapsulates in foods 1898.5.1 Electron microscopy 1908.5.1.1 Scanning electron microscopy 1908.5.1.2 Transmission electron microscopy 1918.5.1.3 Atomic force microscopy 1918.5.1.4 Atmospheric scanning electron microscopy 1928.5.2 Quantification of nanoparticles’ size and mass by electron microscopy 193References 1959 Functional properties of spray dried encapsulates 1989.1 Introduction 1989.2 Controlled release of encapsulated bioactive compounds 1989.2.1 Controlled release by dissolution 1999.2.2 Controlled release by diffusion 1999.3 Masking of off-taste by spray drying encapsulation 2019.4 Improvement in stability of encapsulated bioactive compounds 202References 20810 Analysis of spray dried encapsulates 21010.1 Introduction 21010.2 Analysis of physical characteristics of spray dried encapsulates 21110.2.1 Moisture content 21110.2.2 Particle size 21110.3 Analysis of the efficiency of spray drying encapsulation process 21410.3.1 Estimation of encapsulation efficiency 21410.3.1.1 Encapsulation efficiency of specialty oils 21410.3.1.2 Encapsulation efficiency of vitamins and polyphenolic compounds 21510.3.1.3 Encapsulation efficiency of flavorsand other volatile compounds 21510.3.1.4 Encapsulation efficiency of probiotic cells 21610.4 Analysis of the stability of spray dried microencapsulates 21610.4.1 Analysis of probiotic cell stability under simulated in vitro gastrointestinal conditions 21710.4.2 Analysis of oxidative stability for lipophilic core compounds 21710.4.2.1 Estimation of peroxide value by spectrophotometry method 21710.4.2.2 Rancimat method for estimation of peroxide value 21810.4.2.3 Gas chromatography method for analysis of oxidative stability 21910.4.3 Analysis of the functional properties of spray dried encapsulates 22010.4.3.1 Study of core release from microencapsulates 22010.4.3.2 Taste-masking effects 221References 22211 Modeling approach for spray drying and encapsulation applications 22411.1 Introduction 22411.2 Computational fluid dynamics modeling 22411.2.1 Conservation of mass equation 22511.2.2 Conservation of momentum equation 22511.2.3 Conservation of energy equation 22511.3 Modeling of spray drying process – a theoretical perspective 22911.3.1 Atomization 23011.3.1.1 Boundary conditions for atomization models 23011.3.2 Spray-air contact 23211.3.2.1 Reference frames 23511.3.2.2 Turbulence models 23711.3.2.3 Droplet/particle trajectory 23911.3.2.4 Droplet temperature 23911.3.2.5 Droplet residence time 24011.3.2.6 Particle impact position 24111.3.3 Droplet drying and particle formation 24311.4 Modeling of core release from encapsulates 245References 24912 Synergistic spray drying techniques for encapsulation 25212.1 Introduction 25212.2 Spray fluidized bed coating for encapsulation 25212.2.1 Theory of fluidization 25312.2.2 Fluid bed encapsulation – process steps and influential factors 25312.2.2.1 Atomization 25412.2.2.2 Droplet-particle interactions 25812.2.2.3 Drying of coating material on particle surface 26112.2.2.4 Food ingredient applications of spray fluidized bed coating 26112.2.2.5 Challenges associated with spray fluidized bed coating 26212.2.2.6 Recent advancements in spray fluidized bed coating 26312.3 Spray-freeze-drying for encapsulation 26312.3.1 Spray freezing 26512.3.1.1 Spray freezing into vapor (SFV) 26512.3.1.2 Spray freezing into vapor over liquid (SFV/L) 26512.3.1.3 Spray freezing into liquid (SFL) 26912.3.2 Freeze drying 27012.3.2.1 Conventional freeze drying 27012.3.2.2 Atmospheric freeze drying 27112.3.3 Factors affecting the encapsulation efficiency of SFD process 271References 27313 Industrial relevance and commercial applications of spray dried active food encapsulates 27513.1 Introduction 27513.2 Applications of spray dried encapsulates in the food industries 27613.2.1 Confectionery industry 27613.2.2 Bakery industry 27713.2.3 Other product categories 27813.3 Cost analysis of the spray drying encapsulated active ingredient 27813.4 Major industry players producing spray dried encapsulated food ingredients 28113.4.1 Symrise 28113.4.2 International Flavors & Fragrances (IFF) 28113.4.3 Firmenich 28113.4.4 Givaudan 28213.4.5 Takasago International Corporation 28213.4.6 TasteTech 28213.4.7 Kievit 28213.4.8 Synthite 28213.5 Challenges and future scope of the spray drying encapsulation of food ingredients 283References 284Index 285