Microencapsulation is the technology of packaging solid, liquid and gaseous materials into small capsule by coating the materials with protective matrix or wall materials (Hogan et al. 2001; Cerdeira et al., 2007; Champagne and Fustier, 2007; Madene et al., 2005). In other words, it is a process in which tiny particles or droplets are surrounded by a coating, or embedded in a homogeneous or heterogeneous matrix (Gharsallaoui et al.,2007). The materials within the capsule that are surrounded by coating materials are known as core, internal phase or fill. The core comprise of just one or several ingredients and they can be a crystalline material, a jagged adsorbent particle, an emulsion, a suspension of solids, or a suspension of smaller microcapsules ( Madene et al.,2005; Gharsallaoui et al., 2007).The release of core materials are controlled and depends on the mechanical breaking of matrix, dissolution of coating materials or melting of wall, by diffusion or pressure (Kailasapathy, 2002). The coating materials on the other hand, can be single or double layerred and they are often referred as shell, wall material, carrier, encapsulant or membrane ( Madene et al.,2005; Gharsallaoui et al., 2007).
Microencapsulation is of significant interest to the pharmaceutical sector (e.g. for drug and vaccine delivery), but also have relevance for the food industry (Champagne and Fustier, 2007). In food industry, the core is surrounded by food grade microencapsulating agent (Gharsallaoui et al., 2007). For example, oil droplets of fat products are dispersed in a continuous matrix of proteins, carbohydrates or saccharides or combination of any two of them (Lim et al., 2011). Generally, the process involve drying the pre-prepared oil in water emulsion through techniques such as spray drying or freeze drying. In theory, the microencapsules are in sphere shape with diameters between a few micrometers and a few millimeters but indeed, the shape and size of this particles are vary and depends on the method and materials used (Gharsallaoui et al., 2007). They may range from submicrometer to several millimeters in size and have a multitude of different shapes when the wall materials and microencapsulation processes used are different (Desai and Park, 2005).
The technique of microencapsulation was developed in food industry to protect the sensitive substances from deteoriation caused by adverse environmental factors such as light, oxygen and heat by building a barrier between the subtances and the environment (Desai...