Incorporated microcapsules

In looking at the need for encapuslation in a product it should be emphasized that microcapsules are rarely sold and consumed by themselves. Microcapsules are generally additives to a larger system and must function within that system. Consequently there are a number of performance requirements placed on microcapsules when a limited number of encapsulating materials and methods exist. Consequently it is necessary to make a number of tradeoffs and compromises to incorporate microcapsules into a food product as an additive. In contrast to this, though, there is the continual development of new materials for encapsulation, particluarly in the Wurster method. Fortunately a number of the patents have now expired and so it is possible for the encapsulator to use a number of methods without fear of patent infringement. 

Another possibility to use microencapsulation for food packaging modification is to incorporate microcapsules loaded with dyes as indicators. Higher consumer awareness and the demand for quality and fresh food contributed to the search for new applications and finally to the creation of color control indicators. The main objective of those indicators is to give information to the costumers on... 

On the other hand, the study of Kim et al. proved that the use of gum arabic, whey protein isolate/maltodextrin and poly(vilyl alcohol) as encapsulants to obtain miCToencapsulated cinnamon oil by spray drying resnlted in prolonged repellent effect against P. interpunctella (Hubner) larvae. In this case, LDPE films were coated with either inks containing the microcapsule emulsions or with PP incorporating microcapsule powders. Interestingly, the tensile properties of LDPE were not affected regardless of the method used. ... 

Usami, T. Shimomura, T. Thermal recording material containing dye-precursor-incorporated microcapsules and a dispersion of color developing base. Jpn. Kokai Tokkyo Koho JP 01145190, 1989 Chem. Abstr. 1990,112, 169163. 

Finally, when incorporating microcapsules into coatings it is extremely important that, during the coating process, the microcapsules remain intact. Microcap-... 

Figure 9.4 DTA plots of silicone sol-gel films with or without incorporated microcapsules [1 ]. Curve 1 traditional silicone sol-gel coating. Curve 2 silicone sol-gel composite coating containing organosilicone and ZrOj...

The purpose of incorporating microcapsules into coatings is to improve or repair the surface function of the metal by gradual release of the core materials. In this context, it is very important to study the controlled-release behavior of microcapsules embedded in the composite coating, and of their self-repairing capability for the plating surface. 

Incorporating microcapsules of PCM into textile structures improves the thermal performance of the textiles. Phase change materials store energy when they change from solid to liquid and dissipate it when they... 

Microcapsules are used in several film coatings other than carbonless paper. Encapsulated Hquid crystal formulations coated on polyester film are used to produce a variety of display products including thermometers. Polyester film coated with capsules loaded with leuco dyes analogous to those used in carbonless copy paper is used as a means of measuring line and force pressures (79). Encapsulated deodorants that release their core contents as a function of moisture developed because of sweating represent another commercial appHcation. Microcapsules are incorporated in several cosmetic creams, powders, and cleansing products (80). 

Cortisone acetate has been incorporated into several polyanhydrides (15). The rates of release of cortisone acetate from microcapsules of poly(terephthaUc acid), poly(terephthaUc acid-sebacic acid) 50 50, and poly(carboxyphenoxypropane-sebacic acid) 50 50 are shown in Fig. 8. These microcapsules were produced by an interfacial condensation of a diacyl chloride in methylene chloride with the appropriate dicarboxylic acid in water, with or without the crosslinking agent trimesoyl chloride. This process produces irregular microcapsules with a rough surface. The release rates of cortisone acetate from these microcapsules varied correspondingly with the rate of degradation of the respective polyanhydrides. It can be expected that the duration of release of cortisone acetate from solid microspheres, such as those produced by the hot-melt process, would be considerably longer. 

Microencapsulation with PCL using the solvent evaporation method can be experimentally difficult. For example, PCL was the only polymer of five that failed to yield spherically shaped microcapsules using this technique (82). The insecticide Abate has been incorporated into PCL (21% loading) by the solvent separation method in a comparative study, PCL afforded good-quality microspheres although poly (methyl methacrylate) microcapsules were smoother and had fewer defects (83). 

Solid microcapsules using maltodextrins or starch as matrices were incorporated into cosmetic, pharmaceutical, dietetic, and food compositions using the interfacial crosslinking of flavonoids. Such microcapsules prevented discoloration while maintaining both the anti-free radical and antioxidant activities of the flavonoids." ... 

Re has been incorporated into biodegradable microcapsules formed by polymerization of isobutylcyanoacrylate in the presence of 186Re dispersed in organic solvent. With a mean diameter of 10-15 pm these particles were used for radioembolization therapy of B16 melanoma induced in mice. More than 90% of the injected radioactivity was trapped within the tumors and tumor growth retardation was observed [157],... 

Anhydrous theophylline (100 mesh) was incorporated into a homogenous 5% w/w solution of the corresponding Eudragit in its solvent (Table 1) containing 2-7% w/w of polyisobutadiene. The phase separation and subsequent deposition of the polymer was effected by desolvating the polymer (Table 1) under stirred conditions. Hardening of the microcapsules was effected by dropwise addition of the chilled non-solvent. After the formation of embryonic microcapsules, they were separated, washed with chilled non-solvent and air dried at ambient temperature. 

Matsuda Y, Teraoka R. Improvement of the photostability of ubicarenone microcapsules by incorporating fat-soluble vitamins. Int J Pharm 1985 26 289-301. 

The first plot received 500 g.a.i./h of displarlure as NCR gelatin-walled microcapsules containing 2% ai. The formulation, applied as an aqueous suspension, also contained 1 of sticker to aid adhesion of the formulation to foliage. The second plot received 500 g./h. as Herculite Corporation sprayable laminate flakes containing 9.1 ai. The flakes consisted of two layers of vinyl, each 0.08 mm thick on both sides of a central porous layer containing the disparlure the surface area of the flakes was between 7 and 35 mm2 per side. The same sticker as that in the microcapsules was used. The third plot received 330 g.a.i./h as "Conrel" controlled release hollow fibers containing nominally 11.5% ai. a suitable sticker was also incorporated in the formulation. (Note that the use of trade or proprietary names here or elsewhere does not constitute an endorsement by the USDA). 

Probiotics may be encapsulated in protein-based emulsions. Picot and Lacroix (2003) prepared microcapsules by emulsifying milkfat containing micronized skim milk powder (as a surrogate for freeze-dried bacteria) with heat denatured whey proteins and then spray drying. Incorporation rates of up to 58% milk fat and 29% skim milk... 

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