Gum arabic complex coacervates

Table 1 Hsts representative examples of capsule shell materials used to produce commercial microcapsules along with preferred appHcations. The gelatin—gum arabic complex coacervate treated with glutaraldehyde is specified as nonedible for the intended appHcation, ie, carbonless copy paper, but it has been approved for limited consumption as a shell material for the encapsulation of selected food flavors. Shell material costs vary greatly. The cheapest acceptable shell materials capable of providing desired performance are favored, however, defining the optimal shell material for a given appHcation is not an easy task.

Piacentini,E., L. Giorno,M. M.Dragosavac, G. T. Vlasdisavljevic, andR.G.Holdich,Microencapsulation of oil droplets using cold water fish gelatine/gum arabic complex coacervation by membrane emulsification. Food Res. Int., 53(1) (2013) 362-372. 

Jasmine essential oil Gelatin and gum arabic Complex coacervation Preservation at high temperature [150]... 

In this connection we may remember that formation of foam bodies and hollow spheres (processes which seem closely related) is also induced by a sufficient negativation of the gelatin-gum arabic complex coacervate (see p. 459, 4c and p. 463, 4d),... 

Much has been published on ethanol and sodium sulfate for inducing simple coacervation in gelatin solutions, and on the gelatin-gum arabic complex coacer-vate system. Polyphosphates have been relatively little studied in the literature, but are examples of polyelectrolytes which can participate in both simple and complex coacervate formation. 

Complex Coacervation. This process occurs ia aqueous media and is used primarily to encapsulate water-iminiscible Hquids or water-iasoluble soHds (7). In the complex coacervation of gelatin with gum arabic (Eig. 2), a water-iasoluble core material is dispersed to a desired drop size ia a warm gelatin solution. After gum arabic and water are added to this emulsion, pH of the aqueous phase is typically adjusted to pH 4.0—4.5. This causes a Hquid complex coacervate of gelatin, gum arabic, and water to form. When the coacervate adsorbs on the surface of the core material, a Hquid complex coacervate film surrounds the dispersed core material thereby forming embryo microcapsules. The system is cooled, often below 10°C, ia order to gel the Hquid coacervate sheU. Glutaraldehyde is added and allowed to chemically cross-link the capsule sheU. After treatment with glutaraldehyde, the capsules are either coated onto a substrate or dried to a free-flow powder. 

Eig. 2. Elow diagram of a typical encapsulation process based on the complex coacervation of gelatin with gum arabic. 

Weinbreck, F., de Kruif, C.G. (2003). Complex coacervation of globular proteins and gum arabic. In Dickinson, E., van Vliet, T. (Eds). Food Colloids, Biopolymers and Materials, Cambridge, UK Royal Society of Chemistry, pp. 337-344. 

Complex Coacervation Procedures. Gelatin/alginate (G/A), gelatin/ polyphosphate (G/P), and gelatin/gum arabic (G/GA) complex coacervate and supernatant phases were used in this study. G/A complex coacervate and supernatant phases were formed at pH 4.2 with a 3.7 1 (w/w) mixture of gelatin (227 bloom) and sodium alginate (total solids 1.8 wt. percent). G/P complex coacervate and supernatant phases were formed at pH 4.4 with a 9 1 (w/w) mixture of gelatin (283 bloom) and polyphosphate (total solids ... 

Citrus oils readily form oxygenated products that are likely to congregate at oil/water interfaces and thereby cause a detectable change in IFT. The aldehydic components of citrus oil could react with the amine groups of the gelatin molecules present in the aqueous phases formed by complex coacervation and thereby affect IFT. In addition to chemical reactions, physical changes can occur at an interface and alter IFT. A visible interfacial film can form simply due to interfacial interactions that alter the interfacial solubility of one or more components. No chemical reactions need occur. An example is the formation of a visible interfacial film when 5 wt. per cent aqueous gum arabic solutions are placed in contact with benzene (3). Interfacial films or precipitates can also form when chemical reactions occur and yield products that congregate at interfaces. 

Figure 8.31 Ternary diagram showing complex coacervation region for mixtures of gum arabic and gelatin at pH 4.5 below the curved line the mixture separates into two sols (US Patent 2800457). Insert Typical droplets formed by coacervation (Ronald T. Dodge).

Brungenberg de Jong and coworkers carried out the first extensive studies of complex coacervation (1). They characterized the gelatin-gum arabic coacervation system, a system that later was developed into a process capable of producing microcapsules loaded with a variety of lyophobic materials (2). More recently, an encapsulation process based on the coacervation of gelatin with a polyphosphate has been reported (3). The present paper describes results of a study designed to characterize the gelatin-polyphosphate coacervation interaction and define how various experimental paramenters affect it. 

The development of early encapsulation technology and preparation of microcapsules dates back to 1950s when Green and coworkers produced microencapsulated dyes by complex coacervation of gelatin and gum Arabic, for the manufacture of carbonless copying paper. The technologies developed for carbonless copy paper have led to the development of various microcapsule products in later years. 

FIGURE 12.4 Flow diagram of a typical microencapsulation process based on complex coacervation of gelatin and gum arabic. 

Xiao, J.-X., H.-Y. Yu, and J. Yang, Microencapsulation of sweet orange oil by complex coacervation with soybean protein isolate/gum arabic. Food Chem., 125 (2011) 1267-1272. 

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