Process-Spray pp 941-985 | Cite as

Processing of Functional Capsule Powder Particles Based on Multiple Emulsions Using a Prilling Process

  • Bipro Dubey
  • William Case
  • Erich J. WindhabEmail author


Present studies show the ability of cold spray processing (prilling) to tailor the morphology of simple or double emulsion-based fluid systems as investigated for two types of air-assisted nozzle geometries under various processing conditions. The spray process parameters varied were: (i) gas to liquid flow rate ratio (GLR), (ii) spraying pressure and (iii) total mass flow rate. The results depicted that the emulsion flow inside the nozzle (liquid cap) as well as in the spray (outside nozzle) have distinct impact on the resulting product structure due to the respective flow stresses acting. Increasing the flow stresses either lead to an additional dispersing impact or to separation and coalescence of the disperse fluid phase(s). Besides the process parameters, the material characteristics of the emulsion systems such as viscosity ratio λ of dispersed to continuous phase and the interfacial tension γ were varied in a wider range. The results demonstrated a systematic increase in structure stability for higher λ values within a range of 0.32–30. As representative dimensionless numbers, (a) a critical liquid Weber number Wel,Drop,cr/λ and (b) a critical gas Weber number Weg,Drop,cr/λ were defined to describe the effect of liquid cap-tip and air-assisted spraying, respectively, with respect to preserving the disperse microstructure of the treated emulsions. Above these critical We numbers, the dispersed emulsion phase drops were broken up and drop mean sizes were exponentially decreased due to the flow stresses acting either in the liquid flow inside the nozzle or in the spray filament outside the nozzle. Dynamic viscosity η and dynamic moduli (G′, G″) of treated emulsions increased with decreasing droplet size of the dispersed phase(s) thus altering the spraying performance as well as the properties of the liquid product systems reconstituted from resulting spray-chilled powders. A third critical Weber number Weg,Nozzle,cr was derived for the spray droplet (tertiary droplet) generation by the spray filament breakup providing information of the smallest spray droplet that could be attained, while keeping the dispersed emulsion (secondary) droplets unchanged in size. The impact of Weg,Nozzle on the resulting spray (tertiary) mean drop size was systematically explored for internal (INMIX) and external (EXMIX) liquid-gas mixing air-assisted nozzles. High-speed videography and laser shadowgraphy were applied to visualize liquid spray filament stretching and breakup, as well as the velocity distribution in the sprays. Sufficiently gentle spray conditions for complete preservation of the disperse emulsion structure were only achieved in the Rayleigh filament breakup regime.

Accordingly, a pressure controlled rotary “Rayleigh atomizer” was developed to study emulsion spraying by filament stretching and gently spray drop formation, preserving the emulsion (secondary) droplet structure. At the same time pressure adjustment enabled higher throughput rates compared to conventional rotary spraying nozzles for which only centrifugal forces determine filament stretch and throughput rate simultaneously. Filament length and drop size decreased with increasing rotational speed at a given total pressure (centrifugal pressure + static liquid pressure at the nozzle inlet) or flow rate, and the filament length and drop size increased with higher liquid pressures and related throughput rates at a given rotational speed. Chilling solidification of the spray drops was superimposed in selected cases. Prilling (spraying + chilling) was carried out for various emulsion systems in a prilling tower applying average air temperatures of ca. −10 °C for higher melting fat-continuous emulsions down to −50 °C for low melting oil- or water-continuous emulsions, in order to produce solid powder particles. The micro-structure of the solid particles was analyzed in further detail by cryo-scanning electron microscopy (Cryo-SEM). Concerning emulsion structure preservation in the sprayed products, the results clearly demonstrated that the disperse structure can differ significantly from the initial emulsion structure if critical flow stress conditions are exceeded. Respective process-structure functions were also quantified.

For emulsion-based prilled powders, the applicability and adjustability as functional component carriers for controlled release applications is of big interest in industries such as food, pharmaceutical and cosmetics. For related functional component release experiments we designed an in vitro gastric/duodenal setup. With this, the release kinetics of functional components encapsulated/embedded in dispersed secondary or primary emulsion drop phase(s) were quantified under simulated gastric or duodenal digestion conditions. Accordingly, an iron compound (micronutrient) was encapsulated into the primary and/or secondary dispersed emulsion droplets of simple or double emulsions, and related solid emulsion powder particles were produced through prilling applying our selected air-assist  atomizers. In a first testing step, the iron release kinetics for selected products were systematically investigated in the in vitro gastric system at pH ≈ 2.0, and quantified as a function of prill powder particle size, secondary emulsion drop size and prill powder storage time under ambient conditions.


Viscosity Ratio Drop Size Spray Processing Emulsion Droplet Extensional Viscosity 
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  1. 1.
    Aserin, A. E. (2008). Multiple emulsions: Technology and applications. Hoboken, NJ: Wiley.Google Scholar
  2. 2.
    Leal-Calderon, F., Schmitt, V., & Bibette, J. (2007). Emulsion science: Basic principles. New York: Springer.Google Scholar
  3. 3.
    McClements, D. J. (2010). Emulsion-design to improve the delivery of functional lipophilic components. Annual Review of Food Science and Technology, 1, 241–269.CrossRefGoogle Scholar
  4. 4.
    Florence, A. T., & Whitehill, D. (1981). Some features of breakdown in water-in-oil in water multiple emulsions. Journal of Colloid and Interface Science, 79(1), 243–256.CrossRefGoogle Scholar
  5. 5.
    Tadros, T. F., & Vincent, B. (1983). Chapter 3: Emulsion stability. In P. Becher (Ed.), Encyclopedia of emulsion technology: Vol. I. Basic theory. New York: Marcel Dekker.Google Scholar
  6. 6.
    Frasch-Melnik, S., Spyropoulos, F., & Norton, I. T. (2010). W1/o/w2 double emulsions stabilised by fat crystals—Formulation, stability and salt release. Journal of Colloid and Interface Science, 350, 178–185.CrossRefGoogle Scholar
  7. 7.
    Li, Y. B., Zhang, S. G., & Li, J. G. (2011). Experimental and theoretical approaches on uniform droplets formation from a rationed rotating membrane system. Chemical Engineering Science, 66, 788–796.CrossRefGoogle Scholar
  8. 8.
    Ashgriz, N. (2011). Handbook of atomization and sprays: Theory and applications. New York: Springer.CrossRefGoogle Scholar
  9. 9.
    Dumouchel, C. (2008). On the experimental investigation on primary atomization of liquid streams. Experiments in Fluids, 45, 371–422.CrossRefGoogle Scholar
  10. 10.
    Eggers, J., & Villermaux, E. (2008). Physics of liquid jets. Reports on Progress in Physics, 71, 036601.CrossRefGoogle Scholar
  11. 11.
    Walzel, P. (2010). Spraying and atomizing of liquids; Ullmann’s encyclopedia of industrial chemistry (p. 129). Weinheim, Germany: Wiley-VCH.Google Scholar
  12. 12.
    Christensen, K. L., Pedersen, G. P., & Kristensen, H. G. (2001). Preparation of redispersible dry emulsions by spray drying. International Journal of Pharmaceutics, 212, 187–194.CrossRefGoogle Scholar
  13. 13.
    Bolszo, C. D., Narvaez, A. A., McDonell, V. G., Dunn, D. R., & Sirignano, W. A. (2010). Pressure-swirl atomization of water-in-oil emulsions. Atomization and Sprays, 20(12), 1077–1099.CrossRefGoogle Scholar
  14. 14.
    Kim, W., Yu, T., & Yoon, W. (2012). Atomization characteristics of emulsified fuel oil by instant emulsification. Journal of Mechanical Science and Technology, 26, 1781–1791.CrossRefGoogle Scholar
  15. 15.
    Ochowiak, M. (2012). The effervescent atomization of oil-in-water emulsions. Chemical Engineering and Processing: Process Intensification, 52, 92–101.CrossRefGoogle Scholar
  16. 16.
    Schröder, T., & Walzel, P. (1998). Design of laminar operating rotary atomizers under consideration of the detachment geometry. Chemical Engineering & Technology, 21, 349–354.CrossRefGoogle Scholar
  17. 17.
    Rodriguez-Huezo, M. E., Pedroza-Islas, R., Prado-Barragan, L. A., Berstain, C. I., & Vernon-Carter, E. J. (2004). Microencapsulation by spray drying of multiple emulsions containing carotenoids. Journal of Food Science, 69(7), E351–E359.CrossRefGoogle Scholar
  18. 18.
    Dubey, B. N., Duxenneuner, M. R., Kuechenmeister, C., & Windhab, E. J. (2011). Influences of rheological behavior of emulsions on the spraying process. In Proceedings of 24th Annual Conference on Liquid Atomization and Spray Systems.Google Scholar
  19. 19.
    Dubey, B. N., Duxenneuner, M. R., & Windhab, E. J. (2010). Prilling process: An alternative for the atomization and producing solid particles of emulsions. In Proceedings of 23rd Annual Conference on Liquid Atomization and Spray Systems.Google Scholar
  20. 20.
    Dubey, B. N., & Windhab, E. J. (2013). Iron encapsulated microstructured emulsion particle formation by prilling process and its release kinetics. Journal of Food Engineering, 115(2), 198–206.CrossRefGoogle Scholar
  21. 21.
    Jayasundera, M., Adhikari, B., Aldred, P., & Ghandi, A. (2009). Surface modification of spray dried food and emulsion powders with surface-active proteins: A review. Journal of Food Engineering, 93, 266–277.CrossRefGoogle Scholar
  22. 22.
    Lewandowski, A., Czyzewski, M., & Zbicinski, I. (2012). Morphology and microencapsulation efficiency of foamed spray-dried sunflower oil. Chemical and Process Engineering, 33(1), 95–102.CrossRefGoogle Scholar
  23. 23.
    Jafari, S. M., Assadpoor, E., He, Y., & Bhandari, B. (2008). Encapsulation efficiency of food flavours and oils during spray drying. Drying Technology, 26, 816–835.CrossRefGoogle Scholar
  24. 24.
    McCarthy, N. A., Kelly, A. L., O’Mahony, J. A., Hickey, D. K., Chaurin, V., & Fenelon, M. A. (2012). Effect of protein content on emulsion stability of a model infant formula. International Dairy Journal, 25, 80–86.CrossRefGoogle Scholar
  25. 25.
    Serfert, Y., Schröder, J., Mescher, A., Laackmann, J., Shaikh, M. Q., Rätzke, K., et al. (2013). Characterization of the spray drying behaviour of emulsions containing oil droplets structured interface. Journal of Microencapsulation, 30(4), 325–334.CrossRefGoogle Scholar
  26. 26.
    Taneja, A., Ye, A., Jones, J. R., Archer, R., & Singh, H. (2013). Behaviour of oil droplets during spray drying of milk-protein-stabilised oil-in-water emulsions. International Dairy Journal, 28, 15–23.CrossRefGoogle Scholar
  27. 27.
    Vega, C., & Roos, Y. H. (2006). Invited review: Spray-dried dairy and dairy-like emulsions—Compositional considerations. Journal of Dairy Science, 89, 383–401.CrossRefGoogle Scholar
  28. 28.
    Dollo, G., Corre, P. L., Guerin, A., Chevanne, F., Burgot, J. L., & Leverge, R. (2003). Spray-dried redispersible oil-in-water emulsion to improve oral bioavailability of poorly soluble drugs. European Journal of Pharmaceutical Sciences, 19, 273–280.CrossRefGoogle Scholar
  29. 29.
    Eisner, V. (2007). Emulsions processing with a rotating membrane ROME. PhD Thesis (Diss. ETH No. 17153), ETH Zurich.Google Scholar
  30. 30.
    Bhimani, S., Alvarado, J. L., Annamalai, K., & Marsh, C. (2013). Emission characteristics of methanol-in-canola oil emulsions in a combustion chamber. Journal of Mechanical Science and Technology, 113, 97–106.Google Scholar
  31. 31.
    Matthews, G. A. (1989). Electrostatic spraying of pesticides: A review. Crop Protection, 8, 3–15.CrossRefGoogle Scholar
  32. 32.
    Fujita, N., & Kimura, Y. (2012). Plate-out efficiency related to oil-in-water emulsions supply conditions on cold rolling strip. Journal of Engineering Tribology, 227(5), 413–422.Google Scholar
  33. 33.
    Gradeck, M., Ouattara, A., Maillet, D., Gardin, P., & Lebouche, M. (2011). Heat transfer associated to a hot surface quenched by a jet of oil-in-water emulsion. Experimental Thermal and Fluid Science, 35, 841–847.CrossRefGoogle Scholar
  34. 34.
    Shin, M. J., Kim, J. G., & Shin, J. S. (2012). Microencapsulation of imidazole curing agents by spray-drying method using W/O emulsion. Journal of Applied Polymer Science, 126, E108–E115.CrossRefGoogle Scholar
  35. 35.
    Aghbashlo, M., Mobli, H., Madadlou, A., & Rafiee, S. (2012). The correlation of wall material composition with flow characteristics and encapsulation behavior of fish oil emulsion. Food Research International, 49, 379–388.CrossRefGoogle Scholar
  36. 36.
    Carneiro, H. C., Tonon, R. V., Grosso, C. R., & Hubinger, M. D. (2013). Encapsulation efficiency and oxidative stability of flaxseed oil microencapsulated by spray drying using different combinations of wall materials. Journal of Food Engineering, 115, 443–451.CrossRefGoogle Scholar
  37. 37.
    Drusch, S. (2007). Sugar beet pectin: A novel emulsifying wall component for microencapsulation of lipophilic food ingredients by spray-drying. Food Hydrocolloids, 21, 1223–1228.CrossRefGoogle Scholar
  38. 38.
    Jones, J. R., Prime, D., Leaper, M. C., Richardson, D. J., Rielly, C. D., & Stapley, A. G. (2013). Effect of processing variables and bulk composition on the surface composition of spray dried powders of a model food system. Journal of Food Engineering, 118, 19–30.CrossRefGoogle Scholar
  39. 39.
    Müller-Fischer, N. F., Bleuler, H., & Windhab, E. J. (2007). Dynamically enhanced membrane foaming. Chemical Engineering Science, 62, 4409–4419.CrossRefGoogle Scholar
  40. 40.
    Shi, H., & Kleinstreuer, C. (2007). Simulation and analysis of high-speed droplet spray dynamics. Journal of Fluids Engineering, 129, 621–633.CrossRefGoogle Scholar
  41. 41.
    Dubey, B. N., Duxenneuner, M. R., & Windhab, E. J. (2011). Synthesis of functional food powder of simple and multiple emulsions through prilling process. In Proceedings of 11th International Congress on Engineering and Food.Google Scholar
  42. 42.
    Tang, C., & Li, X. (2013). Microencapsulation properties of soy protein isolate and storage stability of the correspondingly spray-dried emulsions. Food Research International, 52, 419–428.CrossRefGoogle Scholar
  43. 43.
    Desai, K. G., & Park, H. J. (2005). Recent developments in microencapsulation of food ingredients. Drying Technology, 23, 1361–1394.CrossRefGoogle Scholar
  44. 44.
    Gharsallaoui, A., Roudaut, G., Chambin, O., Voilley, A., & Saurel, R. (2007). Applications of spray-drying in microencapsulation of food ingredients: An overview. Food Research International, 40, 1107–1121.CrossRefGoogle Scholar
  45. 45.
    Jyothi, N. V., Prasanna, P. M., Sakarkar, S. N., Prabha, K. S., Ramaiah, P. S., & Srawan, G. Y. (2010). Microencapsulation techniques, factors influencing encapsulation efficiency. Journal of Microencapsulation, 27(3), 187–197.CrossRefGoogle Scholar
  46. 46.
    Soottitantawat, A., Bigeard, F., Yoshii, H., Furuta, T., Ohkawara, M., & Linko, P. (2005). Influence of emulsion and powder size on the stability of encapsulated dlimonene by spray drying. Innovative Food Science and Emerging Technologies, 6, 107–114.CrossRefGoogle Scholar
  47. 47.
    Fäldt, P., & Bergenstähl, B. (1996). Spray-dried whey protein/lactose/soybean oil emulsions. 1. Surface composition and particle structure. Food Hydrocolloids, 10(4), 421–429.CrossRefGoogle Scholar
  48. 48.
    Minemoto, Y., Hakamata, K., Adachi, S., & Matsuno, R. (2002). Oxidation of linoleic acid encapsulated with gum arabic or maltodextrin by spray-drying. Journal of Microencapsulation, 19(2), 181–189.CrossRefGoogle Scholar
  49. 49.
    Tan, L. H., Chan, L. W., & Heng, P. W. (2005). Effect of oil loading on microspheres produced by spray drying. Journal of Microencapsulation, 22(3), 253–259.CrossRefGoogle Scholar
  50. 50.
    Peltonen, L., Hirvonen, J., & Yliruusi, J. (2001). The behavior of sorbitan surfactants at the water-oil interface: Straight-chained hydrocarbons from pentane to dodecane as an oil phase. Journal of Colloid and Interface Science, 240, 272–276.CrossRefGoogle Scholar
  51. 51.
    Bastida-Rodriguez, J. (2013). Review article—The food additive polyglycerol polyricinoleate (E-476): Structure, applications, and production methods. ISRN Chemical Engineering, 2013, 124767. doi: 10.1155/2013/124767.CrossRefGoogle Scholar
  52. 52.
    Graber, M. (2010). Transport phenomena in rotating membrane processed W/O/W emulsions. PhD Thesis (Diss. ETH No. 19079), ETH Zurich.Google Scholar
  53. 53.
    Windhab, E. J. (1999). New developments in crystallization processing. Journal of Thermal Analysis and Calorimetry, 57, 171–180.CrossRefGoogle Scholar
  54. 54.
    Windhab, E. J. (2000). Fluid Immobilization—A structure-related key mechanism for the viscous flow behavior of concentrated suspension systems. Applied Rheology, 10(3), 134–144.Google Scholar
  55. 55.
    Zimmermann, M. B., & Windhab, E. J. Encapsulation of iron and other micronutrients for food fortification. In N. J. Zuidam & V. Nedovic (Eds.), Encapsulation technologies for active Food Ingredients and Food Processing (2010); Springer-Verlag New York, Hardcover ISBN 978-1-4419-1007-3.Google Scholar
  56. 56.
    Mescher, A., & Walzel, P. (2010) Breakup of stretched liquid threads at low gas relative velocities—Comparison of the laminar rotary atomization to the gravity condition. In 23rd Annual Conference on Liquid Atomization and Spray Systems.Google Scholar
  57. 57.
    Mescher, A., & Walzel, P. (2012). Designing thread forming rotary atomizers by similarity trials. In 12th International Conference on Liquid Atomization and Spray Systems.Google Scholar
  58. 58.
    Mescher, A., & Walzel, P. (2012). Gravity affected break-up of laminar threads at low gas-relative-velocities. Chemical Engineering Science, 69(1), 181–192.CrossRefGoogle Scholar
  59. 59.
    N. Garti (1997). Double emulsions-scope, limitations and new achievements; Colloids and Surfaces A: Physicochemical and Eng. Aspects; Vol. 123–124, 15, 233–246.Google Scholar

Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Laboratory of Food Process Engineering (FPE/IFNH)Swiss Federal Institute of Technology Zürich, ETHZürichSwitzerland

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