Encapsulation of caffeine in hydrogel colloidosome: optimization of fabrication, characterization and release kinetics evaluation

Abstract In this research, hydrogel‐based colloidosome with the shell of CaCO 3 microparticles was used to encapsulate caffeine as a model flavour compound. The results of the microscopic evaluation showed that the optimum parameters to fabricate this type of colloidosome were a volume fraction of water equal to 0.2 and a weight of CaCO 3 microparticles to the volume of aqueous solution equal to 0.04 g/ml. In these conditions, when CaCO 3 particles were dispersed in sunflower oil and then water in oil emulsion was prepared, with adding D‐gluconic acid δ‐lactone, water droplets containing alginate slowly gelate with the outer layer of CaCO 3 particles in micrometer hydrogels without coagulation. CaCO 3 microparticles act as both a cross‐linker for the alginate and a stabilizer of water in oil emulsion. After leaving for 48 h, the hydrogel colloidosomes sank to the bottom of the container as a result of gravity. In the optimum state, the colloidosomes had maximum stability and uniformity. After 5 h, this colloidosome sample continued the caffeine release in water up to 55% maximally while using mouth conditions for this sample, the release of the loaded caffeine increased 33% and reached to 73%. Kinetics release of caffeine from colloidosome samples was evaluated using the spectrophotometery method and the measurement of the released caffeine concentration. The results of modelling showed that the Korsmeyer–Peppas model is the best model for describing the release behaviour in mouth conditions ( R 2 ≥ 0.991), whereas the Kopcha model had the maximum coefficient of determination in conditions without shear ( R 2 ≥ 0.968). Overall, release in all colloidosome samples was from the Fickian diffusion type. Copyright © 2015 John Wiley & Sons, Ltd.