Microencapsulation of oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.) essential oils in β-lactoglobulin

Abstract

This study aimed to investigate the microencapsulation of oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.) essential oils by emulsification/freezedrying, using β-lactoglobulin (β-lg) as the coating material. Among the different essential oils, the freeze-dried capsules containing oregano essential oil showed a lower hygroscopicity. Dried powders with higher initial protein concentration exhibited higher bulk tapped density and particle density. The porosity of essential oil-embedded microcapsules ranged from 75.04% to 84.62%, with no significant difference in between different essential oil species (P > 0.05). The overall encapsulation efficiency of essential oils was determined to be in the range of 29.50 – 36.31%. All freeze-dried samples containing essential oils showed significant antioxidant activities in a β-carotene assay, with the percentage of inhibition ranging from 41.05% to 51.02%. The release kinetics of rosemary and sage essential oils from dried microcapsules into phosphate buffer solution were similar, whereas the release of oregano essential oil was considerably lower. FTIR analysis illustrated significant impact of oregano essential oil on the structure change of β-lg.