Microencapsulation by complex

Qv, X. Y., Zeng, Z. P. Jiang, J. G. (2011). Preparation of lutein microencapsulation by complex coacervation method and its physicochemical properties and stability. Food Hydrocolloids, Vol. 25, 6, (August 2011), pp. (1596-1603), ISSN 0268-005X... 

Arneodo, C.J.F. Microencapsulation by complex coacervation at ambient temperature. FR 2732240 Al,... 

Complex coacervation is similar to simple coacervation where another complimentary polyelectrolyte is used. Gelatin and gum arabic is a well-estabHshed system for microencapsulation by complex coacervation. Mayya et al. have reported a two-layer encapsulation of paraffin oil, based on a primary layer of interface active polyelectrolyte-surfactant complex, followed by a second layer of the conjugate polyelectrolyte-polyelectrolyte complex [41]. The procedure involves the dispersion of paraffin oil in 1% gelatin solution (pH adjusted to 6.5) containing SDS having concentration less than its CMC, followed by drop-wise addition of the solution of the other polyelectrolyte (1% gum arabic) into the dispersion. The pH is then ad-... 

Pahnieri, G.F. Lauri, D. Martelli, S. Wehrle, P. Methoxy-butropate microencapsulation by gelatin-acacia complex coacervation. Drug Dev. Ind. Pharm. 1999, 25 (4), 399-407. 

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. 

Thies, C. Microencapsulation of flavors by complex coacervation. In Lakkis, J.M. (d) Encapsulation and Controlled Release Technologies in Eood Systems, Blackwell Publishing, Ames, lA, 2007, pp. 149-170. 

Comunian T, Thomazini M, Alves A, Matos-Jr, F, Balieiro J, Favaro-Trindade C (2013) Microencapsulation of ascorbic acid by complex coacervation Protection and controlled. Food Research International 1 373-379. 

Microencapsulation with complex coacervation has many advantages. It can produce capsules with a payload as high as 95%. The wall of the microcapsules is non-water soluble when it is either cross-linked with chemicals or treated with heat. This is a significant advantage over the microcapsules prepared with other technologies, such as spray drying or fluid bed coating by which the microcapsule wall produced is often water soluble. The microcapsules produced have excellent oxidation stability at low relative humidity, and core release can be initiated by different mechanisms. 

Mendanha,D.V.,S.E.M.Ortiz,C.S.Favaro-Trindade,A.Mauri,E.S.Monterrey-Quintero,andM.Thomazini, Microencapsulation of casein hydrolysate by complex coacervation with SPI/pectin. Food Res. Int., 42 (2009) 1099-1104. 

Nori,M.P.,C.S.Favaro-Trindade,S.M.Alencar,S.M.Thomazini,andJ.C.C.Balieiro,Microencapsulation of propolis extract by complex coacervation. Food Sci. TechnoL, 44 (2010) 429-435. 

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. 

Oliveira, A.C., Moretti, T.S., Boschini, C., Bahero, J.C.C., Freitas, O., andFavaro-Trindade, C.S. 2007. Stability of microencapsulated B lactis (B101) and L acidophilus (LAC 4) by complex coacervation followed by spray drying. J. Microencapsul. 24 685-693. 

FIGURE 36.9 Pectin-soy protein microcapsules containing propolis and obtained at pH 4 produced with (a) concentration of 2.5 g/100 mL (40x), (b) concentration of 5 g/100 mL (lOOx), (c) concentration of 5 g/100 mL (lOOx). (Reprinted from LWT—Food ScL TechnoL, 44(2), Nori, M.P., Favaro-Trindade, C.S., Matias de Alencar, S., Thomazini, M., de Camargo Balieiro, J.C., and Contreras Castillo, C.J., Microencapsulation of propolis extract by complex coacervation, 429-435. Copyright 2011, with permission from Elsevier.)... 

Nori MP, Favaro-Trindade CS, Matias de Alencar S, Thomazini M, de Camargo Balieiro 1C, Contreras Castillo Cl. Microencapsulation of propolis extract by complex coacervation. LWT—Food Sci Technol. 2011 44(2) 429-435. 

Microencapsulation by coacervation is a common method for microcapsules production. It can be achieved by employing different methods, where the most common one is formation of an insoluble complex of two oppositely charged polymers and its subsequent deposition at surface of dispersed particles (e.g. emulsified oil droplets). In this way, microcapsules with coacervate shell are formed. Composition and microstructure of the coacervate shell are key to determine properties and application of microcapsules. 

In this chapter, novel method for microencapsulation by coacervation is presented. The method employs polymer-polymer incompatibility taking place in a ternary system composed of sodium carboxymethyl cellulose (NaCMC), hydroxypropylmethyl cellulose (HPMC), and sodium dodecylsulfate (SDS). In the ternary system, various interactions between HPMC-NaCMC, HPMC-SDS and NaCMC-(HPMC-SDS) take place. The interactions were investigated by carrying out detailed conductometric, tensiometric, turbidimetric, viscosimetric, and rheological study. The interactions may result in coacervate formation as a result of incompatibility between NaCMC molecules and HPMC/SDS complex, where the ternary system phase separates in HPMC/SDS complex rich coacervate and NaCMC rich equilibrium solution. By tuning the interactions in the ternary system coacervate of controlled rheological properties was obtained. Thus obtained coacervate was deposited at the surface of dispersed oil droplets in emulsion, and oil-content microcapsules with a coacervate shell of different properties were obtained. Formation mechanism and stability of the coacervate shell, as well as stability of emulsions depend on HPMC-NaCMC-SDS interaction. Emulsions stabilized with coacervate of different properties were spray dried and powder of microcapsules was obtained. Dispersion properties of microcapsules, and microencapsulation efficiency were investigated and found to depend on both properties of deposited coacervate and the encapsulated oil type. 

Type 3 metal complexes involve the physical interaction of a metal complex, chelates, or metal cluster with an organic polymer or inorganic high molecular weight compound. The preparation of type 3 compounds differs from those of type 1 and type 2, as they are ultimately achieved through the use of adsorption, deposition by evaporation, microencapsulation, and various other methods. 

A problem especially with oxidation catalysts is that the metals in their highest oxidation state tend to be less strongly associated with a support, so that the reaction conditions can lead to leaching of the metal complex from the support. To overcome this problem, microencapsulation, as an immobilization technique for metal complexes, has been introduced by Kobayashi and coworkers. In the microencapsulation method, the metal complex is not attached by covalent bonding but is physically enveloped by a thin film of a polymer, usually polystyrene. With this technique leaching of the metal can be prevented. In 2002, Lattanzi and Leadbeater reported on the use of microencapsulated VO(acac)2 for the epoxidation of allylic alcohols. In the presence of TBHP as oxidant, it was possible to oxidize a variety of substrates with medium to good yields (55-96%) and diastereomeric ratios (60/40 to >98/2) (equation 42). The catalyst is easily prepared and can be reused several times without significant loss in activity. 

Several other investigators have reported microencapsulation methods based upon polyelectrolyte complexes [289, 343]. For example, oppositely-charged polyelectrolytes (Amberlite IR120-P (cationic) and Amberlite IR-400 (anionic)) were recently used along with acacia and albumin to form complex coacervates for controlled release microcapsule formations [343]. Tsai and Levy [344,345] produced submicron microcapsules by interfacial crosslinking of aqueous polyethylene imine) and an organic solution of poly(2,6 dimethyl... 

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