Cross-linked carrageenan beads for controlled release delivery systems

The objective of this study was to prepare and cross-link carrageenan beads that may be used as a controlled release delivery system. The influence of the bulk carrageenan and cross-linker concentrations on the bead size was studied in order to assess the mechanism of cross-linking between epichlorohydrin and the polysaccharide. The conditions were optimised on macroparticles (3.1 mm in diameter) for a better understanding of the cross-link density and its effect on the morphology and surface topography of the bead. It was shown that low epichlorohydrin concentrations led to unstable and weak beads with uneven and cracked surfaces. The optimum cross-linker concentration, which resulted in smooth and stable gel beads, was applied to microparticles (76 mu m in diameter). The swelling/shrinking behaviour of these cross-linked microgels in saline solutions showed great potential for the application of these micro-sponges as delivery systems in food or pharmaceutical products. (C) 2009 Elsevier Ltd. All rights reserved.