Microencapsulation: A Review of Applications in the Food and Pharmaceutical Industries

Abstract

Introduction Definition of microencapsulationThe microencapsulation process is used to entrap small particles of liquids, solids, or gases in one or two polymers. As presented in Fig. 1, the particle component is referred as the core material , and polymers are called variously such as wall material , shell , coating , carrier , or encapsulant (Luzzi, 1970;Desai and Jin Park, 2005). The purpose of microencapsulation is to protect the core material from environmental factors (such as light, moisture, temperature, and oxygen), to extend shelf-life (Shahidi and Han, 1993;Gouin, 2004), and to improve the release properties of compounds (Müller et al., 2002). Microencapsulation has been applied in the design of new materials not only for the food industry but also for pharmaceuticals, cosmetics, and textiles, where the stability, efficiency, and bioactivity of compounds are required (Koo et al., 2014;Dias et al., 2015). Classification of microcapsulesThe selection of the core, wall material, and microencapsulation technique affects the properties of microcapsules, including morphology. Based on the various properties of the core, wall material, and microencapsulation technique, different types of particles (Fig. 2) can be obtained (Gharsallaoui et al., 2007). The morphology of microcapsules can be described as: mononuclear (Fig. 2a), poly/multinuclear (Fig. 2b), matrix (Fig. 2c), multi-wall (Fig. 2d), and irregular (Fig. 2e). Microencapsulation techniquesMicroencapsulation techniques are divided into three classes: chemical, physical, and physico-chemical methods (Jyothi et al., 2010). Chemical methods include in situ polymerization and use of liposomes; physical methods include spray-drying and fluidized bed coating, and physico-chemical methods include coacervation and sol-gel encapsulation (Gibbs, 1999;Gouin, 2004). The microcapsules produced by each method are different (Fang & Bhandari, 2010). Chemical methods In situ polymerizationThe in situ formation of a hydrogel has recently been recognized for its potential biomedical and biotechnological applications

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