Hybrid Microcapsules for Encapsulation and Controlled Release of Rosemary Essential Oil

The foremost objective of this work is to assess the microcapsules composition (polymer-based and polymer/clay-based) effect, on the release of rosemary essential oil into w/o medium and evaluate their antioxidant activity. Calcium alginate (CA) and calcium alginate/montmorillonite hybrid (CA-MTN) microcapsules were developed following an ionotropic crosslinking gelation and were used as host materials for the encapsulation of rosemary essential oil. The unloaded/loaded CA and hybrid CA-MTN microcapsules were characterized by Fourier transform infra-red (FT-ATR) spectroscopy, thermal analysis (TGA), scanning electron microscopy (SEM) and DPPH assay. The evaluation of the microcapsule's physicochemical properties has shown that the clay filling with montmorillonite improved the microcapsule's properties. The encapsulation efficiency improved significantly in hybrid CA-MTN microcapsules and exhibited higher values ranging from 81 for CA to 83% for hybrid CA-MTN and a loading capacity of 71 for CA and 73% for hybrid CA-MTN, owing to the large adsorption capacity of the sodic clay. Moreover, the hybrid CA-MTN microcapsules showed a time-extended release of rosemary essential oil compared to CA microcapsules. Finally, the DPPH assay displayed a higher reduction of free radicals in hybrid CA-MNT-REO (12.8%) than CA-REO (10%) loaded microcapsules. These results proved that the clay-alginate combination provides microcapsules with enhanced properties compared to the polymer-based microcapsules.

Automated summary

The objective of this study was to evaluate the effects of microcapsule composition (polymer-based and polymer/clay-based) on the release of rosemary essential oil and their antioxidant activity. Microcapsules made of calcium alginate (CA) and calcium alginate/montmorillonite hybrid (CA-MTN) were used to encapsulate the oil. The physicochemical characterization showed that the clay filling improved the microcapsule properties, leading to higher encapsulation efficiency and time-extended release of the oil.