Microcapsules, definition

FIGURE 60.1 Aminoplastic microcapsules, definition of capsule size. 

The use of microcapsules in food is generally that of an additive. By regulatory definition, a food additive is any substance which becomes added to food either intentionally or unintentionally other than food itself. This includes both compounds added directly and those that are added indirectly such as migrating from packaging materials. We will limit our discussion here to direct, intentional additives. This means, for example, that the Vitamin C in orange juice is not an additive but the Vitamin C added to orange juice is. 

This definition is more oriented to objectives than on the structure of the microcapsules. It includes a very large number of systems starting from hollow molecules such as cyclodextrin, to large solid microsphers of 2 to 3 mm. It proposes a product-oriented approach, a solution that limits debate around terminologies. 

The general definitions of encapsulation (micro-nano encapsulation) may be applied to any active component X to be encapsulated it is placed in a medium where its mobility and reactivity are reduced, controlled. X is protected inside the microcapsule with a minimal fraction of unprotected X on the surface. 

The core material defined as the specific material to be coated can be liquid or solid in nature. The composition of the core material is varied, as the liquid core can include dispersed and/or dissolved material. The solid core can be a mixture of active constituents, stabilizers, diluents, recipients, and release-rate retardants or accelerators. The ability to vary the core material composition provides definite flexibility, and utilization of this characteristic often allows effectual design and development of the desired microcapsule properties. 

Colloidal surface-polymer interaction, 96 Complex fluids, definition, 1 Configuration of polyelectrolytes adsorbed onto microcapsule surface, 85-94 application in on-off control of enzyme reactions, 91,93/... 

In another report, Scher discussed pesticide microcapsules and reported that these capsules could be used to reduce mammalian toxicity, to extend activity, to reduce phytotoxicity, to protect pesticides from rapid environmental degradation, and to reduce pesticide levels in the environment [68]. Thus, many advantages are obtainable with microcapsular pesticide formulations. In an overview, Gimeno has discussed the definition of the criteria to select an active agent for microencapsulation, together with the techniques used in commercial microencapsulated formulations [69]. 

Chayosumrit M, Tuch B, Sidhu K. Alginate microcapsule for propagation and directed differentiation of hESCs to definitive endoderm. Biomaterials 2010 31 505-514. 

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