Size methods spray-dried emulsions

The dispersed droplet size, referred to as emulsion or particle size, can be reduced in the spray drier infeed matrix by more vigorous mixing or homogenization. There is also a new technique for creating small emulsions termed microfluidization which will be discussed later. This research was designed to determine whether the size of emulsion in the infeed solution will affect the characteristics of the final spray dried powder. Materials and Methods... 

Emulsion Solvent Evaporation The basic concept of the emulsion solvent evaporation technique producing nanoparticles is very straightforward. The particles are formed as an emulsion of a polymer-surfactant mixture and dispersed in an organic solvent. The solvent is then evaporated to leave behind the individual emulsion droplets which form stable free nanoparticles [203], This method is far easier and more preferable over methods such as spray drying and homogenization and operates under ambient conditions and mild emulsification conditions. The size and composition of the final particles are affected by variables such as phase ratio of the emulsion system, organic solvent composition, emulsion concentration, apparatus used, and properties of the polymer [204],... 

Much of the work in this area has been done in emulsions having a droplet size of more than 1 pm, and the application of submicron (nano) emulsions in encapsulation of oils and flavors is relatively new in the literature. Some works have been carried out to determine the influence of submicron emulsions produced by different emulsification methods on encapsulation efficiency and to investigate the encapsulated powder properties after SD for different emulsion droplet sizes and surfactants. The process has been referred to as nanoparticle encapsulation since a core material in nanosize range is encapsulated into a matrix of micron-sized powder particles (Jafari et al., 2008). This area of research is developing. Some patents were filed in the past describing microemulsion formulations applied to flavor protection (Chung et al., 1994 Chmiel et al., 1997) and applications in flavored carbonated beverages (Wolf and Havekotte, 1989). However, there is no clear evidence on how submicron or nanoemulsions can improve the encapsulation efficiency and stability of food flavors and oils into spray-dried powders. 

Recently, Wills et al. [16,17] proposed a novel agglomeration method. Core/shell impact modifiers, useful in toughening polyfvinyl chloride) and other thermoplastics, are prepared at small particle size by an emulsion polymerization process, agglomerated by the novel technique which has little effect on emulsion solid, are further encapsulated by a final shell, and are isolated by spray drying or coagulation. The isolated particles are readily redispersed to their original particle size in the matrix polymer. 

In the latex, the resin may be present as particles as small as 0.2 yum (0.0002 mm) in diameter. On spray drying, some form of agglomeration takes place to yield resins with particle diameters in the 1-2//m (0.001-0.002 mm) range. Thus the dry emulsion-produced resins are approximately one hundredth the size of suspension polymers. On the other hand, this method of manufacture frequently requires the use of relatively large quantities of surfactants, which remain adsorbed on the particle surface. 

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