Matrix encapsulation

Interesting TPEs can be derived from binary and ternary blends of polyfunctional acrylates, ACM, and fluorocarbon rubber (FKM) [53]. During the blend preparation, the liquid multifunctional acrylate monomer used is polymerized and forms the continuous matrix encapsulating the... 

In the literature a difference is made between matrix encapsulation and true encapsulation. In matrix encapsulation the resulting particles are more correctly described as aggregates of actives in a matrix material. A significant portion of the active is lying on the surface of the particles. True encapsulation is used for processes leading to core-shell-type products. However, this distinction of true and matrix is prone to argumentation. 

Alginates, unique hydrocolloids extracted from selected species of brown seaweed (kelp), interact with calcium ions to produce thermally stable gels. Using this interaction, flavor oils may be encapsulated or entrapped in the algin gel matrix. Encapsulation is accomplished at ambient temperatures. Products may be used "as is" (wet) or subsequently dried. This technique offers the potential for novel flavor effects, flavor protection, and new food products. 

Distribution of solutes throughout the matrix can also affect the extraction process. The analytes can be adsorbed on the matrix surface or encapsulated in the matrix. Encapsulated analytes may require harsher extraction conditions or additional preparation steps such as grinding or chopping, prior to extraction. Once this information is collected the chemist can address the problem of developing the extraction method. 

Physical immobilization methods do not involve covalent bond formation with the enzyme, so that the native composition of the enzyme remains unaltered. Physical immobilization methods are subclassified as adsorption, entrapment, and encapsulation methods. Adsorption of proteins to the surface of a carrier is, in principle, reversible, but careful selection of the carrier material and the immobilization conditions can render desorption negligible. Entrapment of enzymes in a cross-linked polymer is accomplished by carrying out the polymerization reaction in the presence of enzyme the enzyme becomes trapped in interstitial spaces in the polymer matrix. Encapsulation of enzymes results in regions of high enzyme concentration being separated from the bulk solvent system by a semipermeable membrane, through which substrate, but not enzyme, may diffuse. Physical immobilization methods are represented in Figure 4.1 (c-e). 

Matrix encapsulation in which the core material is distributed homogeneously within the shell material. 

Matrix encapsulation is the simplest structure, in which the active ingredient (core) is much more dispersed within the carrier/shell material either in the form of relatively small droplets or more homogenously distributed/embedded in a continuous matrix of wall material. The active ingredients in the matrix type morphology are also present at the surface unless there is additional coating applied. 

Layer-by-Layer Deposition Matrix encapsulation Melt-dispersion Microfluidic encapsulation Molecular encapsulation Organogels... 

FIGURE 10.1 Different types of particles (from left to right) core-shell encapsulated particle with a solid or liquid core and a solid shell, core-shell encapsulated particle with a cell suspension inside, classical matrix encapsulated, respectively, granulated particle. 

Microfluidic devices can be used both in NP fabrication and for core-shell and matrix encapsulation structures. 

These droplets subsequently undergo solidification to obtain a matrix encapsulation microsphere, or they could undergo further encapsulation processes to generate uniform core-shell with single or multicore structures. 

Core-shell encapsulation or microgranulation (matrix encapsulation) can be done using a laminar flow through a nozzle and an additional vibration of the nozzle or the liquid (Figure 21.14). 

FIGURE 62.3 Types of microcapsule (a) mononuclear, (b) polynuclear, and (c) matrix encapsulation. 

Mononuclear (core-shell) microcapsules contain the shell around the core, while polynuclear capsules have many cores enclosed within the shell. In matrix encapsulation, the core material is distributed homogeneously into the shell material. In addition to these three basic morphologies, microcapsules can also be mononuclear with multiple shells, or they may form clusters of microcapsules. 

Dehydration processes offer an economical, simple, and flexible means of producing encapsulated flavorings. Dehydration methods yield a particulate powder that contains active flavor ingredients uniformly distributed in the carrier matrix (matrix encapsulation). While any method of dehydration (tray, vacuum tray, freeze, or drum) can and is used for some applications, spray drying is by far the major process used for flavor encapsulation. 

Cuan J, Yan B (2013) Cool-white light emitting hybrid materials of resin-mesoporous silica composite matrix encapsulating europium polyoxometalates through ionic liquid linker. RSC Adv 3 20077-20084... 

---