Several techniques for manufacturing microspheres have been developed, such as electrospray drying [14, 15], solvent evaporation [16-18], emulsion crosslinking [19, 20], ionic gelation technique , direct dispersion method , microfluidic channels , supercritical carbon dioxide , coacervation
method , and free radical emulsion polymerization .
method was used to produce omega-3 nanocapsules.
Physic-chemical processes such as coacervation
methods and liposomes are found to be the fastest growing methods in the micro-encapsulation of food ingredients.
They are produced by coacervation
or phase separation techniques.
The concept of controlled drug delivery was first introduced as a part of pharmaceutical industry via Wurster technique in 1949 and experienced Coacervation
(liquid encapsulation) from 1953, offering microencapsulation technology in 1960 as a milestone in this progress .
Nanoparticles are generally prepared by three methods: (i) dispersion of preformed polymers; (ii) polymerization of monomers; and (iii) ionic gelation or coacervation
of hydrophilic polymers.
Different techniques performing encapsulation are spray drying, spray chilling, molecular inclusion, coacervation
, and extrusion.
New encapsulation technologies include: spray freezing, fluid bed, pan coating and coacervation
PN-HCl was encapsulated with sodium alginate by emulsion coacervation
process before being supplemented in the experimental diets.
However, the encapsulation method of complex coacervation
of gelatin and gun arabic introduced two miscible poylelectrolytes that formed a liquidliquid phase.
The original types of phenolic resins used with PEO were marginally water-soluble so the PEO/cofactor complex tended to undergo coacervation
(shrinking) followed by precipitation.
Table 5 - nature of polymeric material Polyamide Interfacial polycondensation Poly(alkyl cyanoacrylate) Emulsion polymerization Albumin, polysaccharide Suspension crosslinking Gelatin, gum arabic, Coacervation
ethylcellulose Biodegradable polyester Solvent evaporation/ Cellulose acetate Solvent extraction Synthetic polymers Solvent evaporation/ Polystyrene Solvent extraction Polycarbonate Polystyrene-methyl methacrylate Polyester Silicone