Microparticles obtained by complex coacervation: influence of the type of reticulation and the drying process on the release of the core material

Microparticles obtained by complex coacervation were crosslinked with glutaraldehyde or with transglutaminase and dried using freeze drying or spray drying. Moist samples presented Encapsulation Efficiency (%EE) higher than 96%. The mean diameters ranged from 43.7 +/- 3.4 to 96.4 +/- 10.3 mu m for moist samples, from 38.1 +/- 5.36 to 65.2 +/- 16.1 mu m for dried samples, and from 62.5 +/- 7.5 to 106.9 +/- 26.1 mu m for rehydrated microparticles. The integrity of the particles without crosslinking was maintained when freeze drying was used. After spray drying, only crosslinked samples were able to maintain the wall integrity. Microparticles had a round shape and in the case of dried samples rugged walls apparently without cracks were observed. Core distribution inside the particles was multinuclear and homogeneous and core release was evaluated using anhydrous ethanol. Moist particles crosslinked with glutaraldehyde at the concentration of 1.0 mM.g(-1) protein (ptn), were more efficient with respect to the core retention compared to 0.1 mM.g(-1) ptn or those crosslinked with transglutaminase (10 U.g(-1) ptn). The drying processes had a strong influence on the core release profile reducing the amount released to all dry samples.