Encapsulation of Solid Materials

In addition to molecularly distributed compounds, the material can also be encapsulated as aggregate, crystal, etc., as is the case for the encapsulation of pigments and, for thermally labile azo-components, photoinitiators, and highly fluorescent quantum dots in polymeric nanoparticles by using the miniemulsion process. 

The material is protected by the polymer (quantum dots, magnetite, silica) 

The material can act as marker and the nanoparticle can be further functionalized (magnetite, quantum dots) 

The material can be released under defined conditions (e.g., photoinitiator) Dispersions containing the encapsulated material show improved stability against aggregation (e.g., pigments, carbon black, etc.) 

After film formation, the material is embedded in the polymer and homogeneously distributed (as aggregates) all over the film (pigments) 

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McCann JT, Marquez M and Xia Y, Melt coaxial electrospinning a versatile method for the encapsulation of solid materials and fabrication of phase change nanofibers . Nano Lett., 2006,6,2868-2872. 

Another product has basically a built-in pH sensor. In this case the rinse aid is encapsulated into a material that is solid and insoluble in water at an alkaline pH-value. Thus it is able to withstand the conditions in the alkaline main wash cycle. When the pH-value decreases, due to the dilution of the washing liquor with pure water in the rinse cycles, the sensor encapsulation material becomes soluble and releases its contents [93, 94]. 

Immobilization is the process of incorporating waste into a matrix material for solidification, or directly into a storage and/or final disposal container. More specifically, solidification can be defined as encapsulation of a waste in a solid of high structural integrity (Freeman, 1998). At the same time, the goal of the solidification process is the stabilization of the waste, which means that the risk posed by the waste is reduced by converting it into a less soluble and less mobile form (Freeman, 1998). 

The matrix used for the encapsulation of juice solids was a mixture of low DE maltodextrin (DE 10) and lactose. A typical formulation prior to cooking would be 23% water, 26% lactose and 51% maltodextrin. This material was cooked to the desired temperature (ca. 110 C), mixed with 85 Brix juice solids and optionally, peel oil, extruded, washed and dried. The extrusion process is essentially the same as used by Swisher (3), A product containing up to 40% juice solids may be produced via this process. This loading of juice solids is substantially greater than the 10-15% juice solids loading claimed by Barnes and Steinke ( 5 ). 

Inorganic Materials. Sol-gel chemistry involves first the formation of a sol, which is a suspension of solid particles in a liquid, then of a gel, which is a diphasic material with a solid encapsulating a solvent A detailed description of the fundamental chemistry is available in the literature. The chemistry involving die must commonly used precursors, the alkoxides (M(OR) ,). can be described in terms of two classes of reactions ... 

A number of food ingredients or additives have been encapsulated and arc availahle commercially. Solid ingredients encapsulated arc typically water-soluble and arc encapsulated with a hydrophobic or hydrophilic coaling material usually applied hy the Wursler process. Both types of coaling materials are well-accepted food-grade products (see Food Additivesi. 

Various techniques available for characterization of solid-state properties of raw materials and Ln-ished solid dispersions are presented in this section. In most cases, solid dispersions are process into Lnished dosage forms using conventional approaches such as tabletting, encapsulation, and < forth, and the characterization of such Lnished dosage formulations are not presented here. 

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