Morphology and release profile of microcapsules encapsulating peppermint oil by complex coacervation

The gelatin/gum Arabic microcapsules encapsulating peppermint oil were prepared by complex coacervation using transglutaminase as hardening agent. The release of microcapsules was investigated in different dispersing media. The release of microcapsules separately followed first order release kinetics model in hot water and zero order release kinetics model in high-temperature oven. The release of microcapsules in hot water exhibited initial rapid release phase and following slow release phase, where effect of core/wall ratio on the release rate was different due to the increase of loading and particle size with the core/wall ratio. The release kinetics rate constant, K, was analyzed by an Arrhenius plot and found to fit well with a linear relation between in ln(K) and 1/T. The activation energy was evaluated to be 32.6 kJ mol−1. The microcapsules were only release about 7% of peppermint oil during the storage of 40 days in cold water, exhibiting excellent storage stability.