Assessment of encapsulation efficiency of caffeine in alginate hydrogel beads blended with natural biopolymers

In this study, alginate-based carrier systems consisting of carageenan, pectin or chitosan were formulated in order to evaluate the potential of caffeine encapsulation (as the model drug), with the aim of achieving its prolonged release and better encapsulation efficiency. For that purpose, plain alginate, alginate-pectin and alginate-carageenan beads were formulated and the latter two additionally coated with chitosan or pectin to evaluate whether coating can improve the encapsulation attributes of obtained beads. Particle size, encapsulation efficiency, release profiles in water, simulated gastric (SGF) and intestinal fluids (SIF) and FTIR spectra of formulated hydrogel beads were determined. According to the obtained results alginate-carrageen as the immobilization system for caffeine provided the largest particles (2.32 mm), while employing chitosan or pectin coating around the formed particles provided larger and irregularly shaped beads. The highest encapsulation efficiency of caffeine was achieved using the alginate-pectin formulation (79.7%), while the introduction of chitosan coating slightly enhanced the ability to entrap this compound. The release study in water revealed similar caffeine release kinetics for all evaluated carrier systems, with the majority of caffeine being released from the beads already during the initial 5-10 minutes of experiment. More pronounced release patterns of caffeine were determined in beads placed in SGF and SIF in comparison to water as the release medium. The release of caffeine was much slower from the coated particles, especially for the pectin coated alginate-carageenan beads in SGF and chitosan coated alginate-pectin beads in SIF, where the release of caffeine occurred gradually during 2h, probably as the result of coating formation that retarded the diffusion of caffeine from the particles. The obtained results indicate that the employed blended carrier systems are efficient to achieve a high encapsulation efficiency of caffeine, but further optimization is needed to prolong the release of caffeine from the beads in a liquid medium.