ABSTRACT
Microencapsulation is a technology that permits the formation of structures whose main functions are the protection and controlled release of substances. Enzymes, cells, bioactive substances, dyes, avors, and adjuvants of technology, among other named core or active substances, can be microencapsulated and applied to various products, having preserved their properties and activities against processing conditions, storage, or end uses. Several industrial areas, including the food products, cosmetics, pharmaceutics, veterinary, agricultural, chemical, automotive paints, and printing industries, are using microencapsulation to produce differentiated ingredients that are used to obtain innovative products (Shahidi and Han 1993). In addition to the classic applications in the food industry to mask undesirable avors and odors and to facilitate handling of volatile liquid compounds by converting them into solid powders (Byun et al. 2010), encapsulation also aims to protect the encapsulated material from the adverse conditions of the medium, including light, oxygen, temperature, humidity, pH (Gibbs et al. 1999), and biological conditions, present during product ingestion and absorption in the gastrointestinal tract (Jones and McClements 2010). Moreover, encapsulation ensures the controlled release of the encapsulated active material at the desired site and time for maximum effectiveness of the active agent (Desai and Park 2005). These effects can be obtained by coating the active material or by inserting it into a lm or wall material matrix, resulting in the development of encapsulated materials with different shapes and sizes, including nano-, micro-, and macrosized (Augustin and Hemar 2009; Thies 1995). Many different methods for preparing encapsulated materials are available, some of which have been widely adopted and are known with respect to their chemical, physical, or physicochemical properties. These methods include spray drying, spray chilling, and cooling, uid bed coating, complex coacervation, liposome production, extrusion processes using carbohydrates or ionic gelation, spinning disc/centrifugal extrusion, and molecular inclusion, among others (Shahidi and Han 1993). Recently, we have observed an exponential growth of new methods that are still little explored regarding the principles that allow the encapsulation of active agents and the properties of encapsulated materials. These methods include supercritical systems and the use of combined techniques to produce encapsulated
16.1 Introduction ................................................................................................................................ 299 16.2 Wall Materials: Properties and Physicochemical Characterization .......................................... 301 16.3 Core and Bioactive Materials ..................................................................................................... 302 16.4 Triggers and Release Mechanisms ............................................................................................. 304 16.5 Spray Drying .............................................................................................................................. 305 16.6 Spray Chilling/Cooling .............................................................................................................. 306 16.7 Fluid Bed Coating ...................................................................................................................... 307 16.8 Coacervation .............................................................................................................................. 308 16.9 Ionic Gelation ............................................................................................................................. 309 16.10 Combination of Ionic Gelation and Electrostatic Interaction .....................................................310 References ...............................................................................................................................................311
