Drying microencapsulation

These results show the functional ability of GA to act as quencher of electronically excited states in food systems either as non-processed gum or spray-drying microencapsulated preparations. 

Spray drying. Microencapsulation by spray drying is an ideal method for poorly water-soluble drugs. The drug is dispersed in polymer (coating) solution, and then this dispersion is atomized into an airstream. The air, usually heated, supplies the latent heat of vaporization required to remove the solvent and forms the microencapsulated product. This technique is employed most commonly when microcapsules are intended for oral use because the resulting microspheres are porous in nature, and large batch sizes are required.89... 

Jimenez, M., Garcia, H.S., and Beristain, C.I. (2004). Spray-drying microencapsulation and oxidative stability of conjugated linoleic acid. Eur. Food Res. Technol. 219, 588 592. 

Takenaka, H. Kawashima, Y. Lin, S.Y. Polymorphism of spray-dried microencapsulated sulfamethoxazole with cellulose acetate phthalate and colloidal silica, montmoril-lonite, or talc. J. Pharm. Sci. 1981, 70, 1256-1260. 

Rosenberg M., Kopelman I.J., and Tahnon Y., 1990. Factors affecting retention in spray drying microencapsulation of volatile materials. Journal of Agricultural and Food Chemistry, 38,1288-1294. 

Velasco, J., Dobarganes, C., Marquez-Ruiz, G., 2003. Variables affecting lipid oxidation in dried microencapsulated oils. Grasas y Aceites 54 304-314. 

Several parenteral microencapsulated products have been commercialized the cote materials ate polypeptides with hormonal activity. Poly(lactide— glycohde) copolymers ate the sheU materials used. The capsules ate produced by solvent evaporation, polymer-polymer phase separation, or spray-dry encapsulation processes. They release their cote material over a 30 day period in vivo, although not at a constant rate. 

The encapsulation of herbicides has received much attention. Encapsulated alachlor is a high volume herbicide product generally sold as a Hquid formulation, although a dry granule version is also available. The capsules, produced by interfacial polymeri2ation (11), are reported to be spherical with a diameter of 2—15 p.m (75). Two thiocarbamate herbicides, EPTC and vemolate [1929-77-7], were encapsulated by interfacial polymeri2ation because they are volatile compounds. When appHed in unencapsulated form, they must be incorporated in the soil within two hours in order to provide effective weed control. When appHed as a microencapsulated formulation, the rate of volatili2ation is lower and soil incorporation can be delayed 24 hours (76). 

In addition, Montenegro et al., (2007) determined that the photosensitized RF-mediated degradation of vitamins A, D3, and RF itself in skimmed milk was strongly reduced by the addition of small amounts of lycopene-gum arabic-sucrose microcapsules, prepared by spray-drying. Under these conditions, the bulk properties of the skimmed milk were unmodified. The main photoprotection mechanism of the milk vitamins was the efficient quenching of the 3Rf by the protein moiety of GA. Small contributions (<5%) to the total photoprotection percentage was due to both inner filter effect and 1O2 quenching by the microencapsulated lycopene. 

K Heinzelmann, K Franke. Using freezing and drying techniques of emulsions for the microencapsulation of fish oil to improve oxidation stability. Colloids Surfaces B Biointerfaces 12(3—6) 223—229, 1999. 

Gharsallaoui, A., G. Roudaut, O. Chambin et al. 2007. Applications of spray-drying in microencapsulation of food ingredients An overview. Food Res. Int. 40 1107-1121. 

Caprylic/capric triglyceride, cosmetically useful lipid, 7 833t Capsanthin, 24 560 Capsicum group, 23 164-165 Capsorubin, 24 560 Capsular polysaccharides, 20 455 Capsules. See also Microencapsulation extruding, 16 446 pharmaceutical, 18 708 produced by spray drying, 16 447-448 Capsule standard platinum resistance thermometers, 24 445 Captafol, 23 629, 647 Captan, 23 628 Captiva camera, 19 307 Captive hydrogen, 13 841 Captopril, 5 148... 

Microencapsulation using extrusion is mainly described for glassy carbohydrate matrices [14-16, 28-29]. The glassy carbohydrates, such as starch and maltodextrins, are melted at elevated temperature and low water contents and are intensively mixed with the active in the extrusion barrel. Extrusion has been used for volatile and unstable flavours. The shelf life of flavour oils could be extended from several months to 5 years, compared with 1 year for spray-dried materials. The main drawbacks of the technology are the high investments costs and the formation of rather large particles (500-1,000 pm). 

Desai, K.G., Park, H.J. (2005). Encapsulation of vitamin C in tripolyphosphate cross-linked chitosan microspheres by spray drying. Journal of Microencapsulation, 2, 179-192. 

Keogh, M.K., O Kennedy, B.T., Kelly, J., Auty, M.A., Kelly, P.M., Fureby, A., Haahr, A.-M. (2001). Stability to oxidation of spray-dried fish oil powder microencapsulated using milk ingredients. Journal of Food Science, 66, 217-224. 

Giunchedi P, Gavini E, Bonacucina G, Palmieri GF. Tabletted polylactide microspheres prepared by a w/o emulsion-spray drying method. J Microencapsul 2000 17(6) 711-720. 

The term aqueous phase separation is often more simply described as oil-in-water microencapsulation. The two encapsulation processes described above are examples of this oil-in-water encapsulation. In this process the core material is the oil and it should be immisible in the continuous phase, namely water. A commercial example of aqueous phase separation would be the microencapsulation of an oily flavor such as sour cream with a gelatin wall. These microcapsules would then be dispersed in a dry cake mix. The mechanism of release would be during the moist baking cycle of the cake, moist-heat causing the capsule walls to first swell and then rupture. 

G. A. Reineccius, The Spray Drying of Food Ingredients, in Microencapsulation of Food Ingredients, edited by B. Per Vilstrup (Leatherhead Food RA, Leatherhead, UK, 2000), pp. 151-185. 

Since the core materials are microencapsulated while being dispersed in some liquid manufacturing vehicle, subsequent drying operations are usually required. 

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