About the editorC. Anandharamakrishnan is Director at the Indian Institute of Crop Processing Technology (IICPT), Thanjavur, India. Before assuming responsibility as Director, IICPT, he was Principal Scientist in the Food Engineering Department of the CSIR – Central Food Technological Research Institute, Mysore, India. He has been active in the field of spray drying for the past 10 years, working on the micro- and nanoencapsulation of nutraceuticals and computational fluid dynamics modelling of spray drying. He completed a PhD on spray drying and spray-freeze drying of proteins at Loughborough University, UK.

• Contributors xiiiAbout the editor xvPreface xviiAcknowledgments xix1 Introduction to Drying 1C. Anandharamakrishnan1.1 Introduction 11.2 Fundamental principles of drying: the concept of simultaneous heat and mass transfer 21.2.1 Heat transfer during the drying process 21.2.1.1 Conduction drying 31.2.1.2 Convection drying 41.2.1.3 Radiation and dielectric drying 51.2.2 Mass transfer during the drying process 61.2.2.1 Diffusion mechanism 71.2.2.2 Capillary mechanism 81.3 The drying curve 91.4 Stages of drying 91.4.1 Constant rate period 101.4.2 Falling rate period 111.5 Techniques for the drying of dairy products 121.6 Conclusion 13References 132 Dried Dairy Products and their Trends in the Global Market 15Aadinath, T. Ghosh, P.H. Amaladhas and C. Anandharamakrishnan2.1 Introduction 152.2 Milk powders and dried milk products 162.2.1 Primary dairy powders 162.2.2 Secondary dairy powders 162.3 World market dynamics 182.3.1 Production 182.3.1.1 Oceania 182.3.1.2 India 202.3.1.3 European Union 202.3.1.4 Argentina 202.3.2 Consumption 202.3.2.1 Algeria 202.3.2.2 Indonesia 212.3.2.3 China 212.3.2.4 Mexico 21References 213 Techniques for the Preconcentration of Milk 23I. Roy, A. Bhushani and C. Anandharamakrishnan3.1 Introduction 233.2 Need for preconcentration 233.2.1 Skim milk 243.2.2 Whey powders and infant formula 243.3 Concentration methods 253.4 Thermal methods 253.4.1 Evaporation 253.4.1.1 Single-effect recirculation evaporator 253.4.1.2 Multiple-effect evaporator 263.4.1.3 Falling-film evaporator 273.4.1.4 Plate evaporator 283.4.1.5 Horizontal tube evaporator 303.4.1.6 Mechanical film evaporator 303.4.1.7 Low-temperature evaporator 303.5 Non-thermal methods 303.5.1 Freeze concentration 303.5.2 Membrane separation techniques 323.5.2.1 Microfiltration 343.5.2.2 Ultrafiltration 353.5.2.3 Reverse osmosis 373.6 Conclusion 37References 374 Drum Drying 43P. Karthik, N. Chhanwal and C. Anandharamakrishnan4.1 Introduction 434.2 Drum-drying process 444.2.1 Effect of operating parameters on product quality and the capacity of the drum dryer 454.3 Types of drum dryers 464.3.1 Single-drum dryers 464.3.2 Double-drum dryers 474.3.3 Twin-drum dryers 474.3.4 Vacuum-drum dryers 484.3.5 Enclosed-drum dryers 494.4 Classification of the feeding method 494.4.1 Single- and multiple-roll feed 494.4.2 Nip feed 494.4.3 Dip feed 494.4.4 Spray feed 494.4.5 Splash feed 504.5 Operating parameters 514.5.1 Important operational conditions in the drum drying of milk 524.6 Advantages and disadvantages of drum/roller drying 544.7 Conclusion 54References 555 Spray Drying 57S. Padma Ishwarya and C. Anandharamakrishnan5.1 Introduction 575.2 Spray drying: principle of operation 575.2.1 Atomization 595.2.1.1 Rotary atomizers 605.2.1.2 Pressure nozzle atomizers 625.2.1.3 Twin-fluid atomizers 625.2.1.4 Monodisperse droplet generators 635.2.2 Droplet–drying air interaction and moisture evaporation 655.2.3 Particle separation 725.3 Characteristics of spray-dried dairy powders 745.3.1 Rehydration 745.3.2 Particle size and shape parameters 755.4 Handling spray-drying processing problems 775.4.1 Stickiness 775.4.2 Thermal denaturation of proteins 795.5 Applications of spray drying for the production of dried milk and milk products 795.6 Conclusion 84References 886 Freeze Drying 95A. Bhushani and C. Anandharamakrishnan6.1 Introduction 956.2 Steps in freeze drying 956.2.1 Freezing 966.2.2 Primary or sublimation drying 996.2.3 Secondary or desorption drying 1006.3 Merits of freeze drying over other drying techniques 1006.4 Heat and mass transfer in freeze drying 1016.5 Freeze-drying equipment 1036.6 Properties influencing the freeze drying of dairy products 1066.6.1 Milk 1066.6.2 Lactose 1096.7 Preservation of kefir culture by freeze drying 1116.8 Microencapsulation of probiotics by freeze drying 1126.8.1 Probiotics 1126.8.2 Need for microencapsulation 1136.8.3 Cell viability issues associated with freeze drying 1136.8.4 Characteristics of microencapsulated probiotic cells 1146.9 Conclusion 115References 1177 Spray Freeze Drying 123S. Padma Ishwarya, C. Anandharamakrishnan and A.G.F. Stapley7.1 Introduction 1237.2 SFD process 1247.2.1 Atomization 1257.2.2 Freezing 1267.2.2.1 Spray freezing into vapour 1277.2.2.2 Spray freezing into vapour over liquid 1277.2.2.3 Spray freezing into liquid 1297.2.3 Freeze drying 1307.2.3.1 Vacuum freeze drying 1307.2.3.2 Atmospheric SFD and atmospheric spray fluidized-bed freeze drying 1317.2.3.3 Sub-atmospheric pressure SFD 1327.3 Applications of SFD in dried dairy products 1327.3.1 SFD of whole milk and skim milk 1337.3.2 SFD of whey protein 1357.3.3 SFD for microencapsulation of probiotics 1407.4 Advantages and limitations of SFD 1447.5 Conclusion 144References 1448 Optimization of Dairy Product Drying Processes 149S. Parthasarathi and C. Anandharamakrishnan8.1 Introduction 1498.2 Experimental design tools for process optimization 1498.2.1 Response surface methodology 1498.2.1.1 Advantages of RSM 1518.2.1.2 Limitations of RSM 1518.2.2 Artificial neural networks 1518.2.2.1 Feed-forward neural network 1528.2.2.2 Learning process of an ANN 1538.2.2.3 Optimization of process parameters 1548.2.3 Finite element and finite volume methods 1548.2.3.1 Finite element method 1558.2.3.2 Finite volume method 1558.3 Drying process variables and their influence on process and product quality 1568.3.1 Drum drying 1578.3.1.1 Heat and mass transfer 1578.3.2 Spray drying 1588.3.2.1 Exergy efficiency 1608.3.2.2 Atomization 1608.3.3 Freeze drying 1618.3.3.1 Temperature measurement 1628.3.3.2 Computational modelling 1648.3.4 Spray freeze drying 1698.4 Conclusion 170References 1719 Computational Fluid Dynamics Modelling of the Dairy Drying Processes 179J. Gimbun, W.P. Law and C. Anandharamakrishnan9.1 Introduction 1799.2 Spray drying 1799.2.1 Spray-drying process 1799.2.2 Flow field simulation 1809.2.2.1 Steady or unsteady approach 1819.2.2.2 Turbulence modelling 1829.2.3 Discrete phase modelling 1839.2.4 Wall deposition and the particle build-up model 1869.2.5 Particle interaction 1869.2.6 Validation and issues of CFD simulation 1899.3 Freeze drying 1899.3.1 Modelling of freeze drying 1909.3.1.1 Mass and heat-transfer modelling 1909.3.1.2 Primary drying modelling 1919.3.1.3 Secondary drying modelling 1929.4 Spray freeze drying 1939.5 Conclusions and future scope 196References 19610 Physicochemical and Sensory Properties of Dried Dairy Products 203P.H. Amaladhas and F. Magdaline Eljeeva Emerald10.1 Introduction 20310.2 Milk Powder Manufacture 20310.2.1 Roller drying 20510.2.2 Spray drying 20610.2.3 Freeze drying 20810.2.4 Spray freeze drying 20810.3 Properties of dairy powders as influenced by drying method 20810.4 Physical properties 20910.4.1 Morphology, particle size, shape and distribution 20910.4.2 Density 21010.4.3 Reconstitution properties 21310.4.4 Agglomeration and instantization 21610.4.5 Flowability and stickiness 21610.4.6 Heat and coffee stability 21710.5 Chemical and sensory properties 21810.5.1 Protein quality 21810.5.2 Non-enzymatic browning 21910.5.3 Oxidation and chemical quality 21910.5.4 Sensory quality 22010.6 Properties of special powders 22010.6.1 Whey powders 22010.6.2 Whey protein concentrates 22110.6.3 Cheese powder 22110.6.4 Yoghurt powder 22210.6.5 Infant milk powders 22210.6.6 Dairy whiteners 22310.7 Conclusion 223References 22311 Packaging of Dried Dairy Products 229R. Gopirajah and C. Anandharamakrishnan11.1 Introduction 22911.2 Dairy packaging trends 23011.3 Forms of packaging materials 23111.3.1 Metal cans 23211.3.2 Glass bottles 23211.3.3 Stretch-wrap packaging 23211.3.4 Flexible pouches 23211.3.5 Bag-in-box packages 23311.3.6 Cups 23311.3.7 Paper-board containers 23311.4 Packaging of dried milk products 23411.4.1 Packaging of whole milk powder 23511.4.2 Packaging of non-fat dried milk powder 23611.5 Developments in packaging techniques 23711.5.1 Intelligent packaging 23711.5.2 Active packaging 23811.5.2.1 Migration mechanism in active packaging 23911.5.2.2 The use of scavengers (absorbers) to prevent lipid oxidation 23911.5.3 Nanotechnology in dairy packaging 24011.5.3.1 Bionanocomposites and their applications 24111.5.3.2 Modelling the barrier properties of polymer-clay nanocomposites 24211.6 Conclusion 244References 24412 Recent Advances in the Drying of Dairy Products 249M.W. Woo12.1 Introduction 24912.2 Typical layout of a dairy spray-drying process 25012.2.1 Multistage drying process 25012.2.2 Some unique process layouts 25112.3 Advances in operating spray dryers 25212.3.1 Controlling the drying process 25212.3.1.1 Single droplet to dryer-wide prediction 25212.3.2 Controlling powder stickiness and deposition 25912.4 Advances in operating fluidized-bed dryers 26112.4.1 Controlling crystallization 26112.4.2 Controlling agglomeration 26212.5 Conclusion 263References 26313 Industrial Scale Drying of Dairy Products 269D. Anand Paul13.1 Introduction 26913.2 Process flow in a dairy drying plant 27013.3 Lexicon of industrial-scale drying 27213.4 Industrial spray drying of dairy products 27313.4.1 Automation of industrial-scale spray dryers 27313.4.2 Efficiency of spray-dryer operation 27413.4.3 Bottlenecks in industrial spray-drying 27613.4.4 Hygiene in spray-dryer operation 27713.4.5 Safety aspects of spray drying 27813.5 Industrial drum drying of dairy products 27913.5.1 Critical control points in industrial drum drying 28013.5.2 Energy efficiency of drum drying 28213.5.3 Safe operation of drum dryers 28313.6 Conclusion 283References 28314 Challenges Involved in the Drying of Dairy Powders 287U. Kiran Kolli14.1 Introduction 28714.2 Challenges in the drying of dairy powders 28814.2.1 Fouling 28814.2.1.1 Mechanisms 28814.2.1.2 Factors affecting fouling 28914.2.2 Stickiness 29114.2.3 Fires and explosions 29214.2.4 Powder loss 29314.2.5 Transport of powder 29314.2.6 Storage of dairy powders 29414.2.7 Plant economics 29414.2.8 Development of speciality dairy powders 29414.3 Use of modelling as a tool to solve some challenges 29514.4 Conclusion 296References 296Index 301