Microencapsulation of Zanthoxylum schinifolium essential oil through emulsification followed by spray drying: microcapsule characterization and functional evaluation

The strategy of microencapsulation combining emulsification and spray drying is a facile method to improve the lipid stability and application range of spice essential oils. We hypothesized that the physicochemical and functional properties of Zanthoxylum schinifolium essential oil (ZSEO) could be improved if ZSEO microcapsules were prepared through emulsification followed by spray drying using gelatin/microcrystalline cellulose complexes as emulsifiers and maltodextrin as wall material. The oil-in-water (O/W) emulsions as a function of ZSEO content (4.5-6.5 wt%) were characterized by morphology, droplet size, and rheology analyses. Additionally, the effects of maltodextrin concentration (7-15 wt%) on the physicochemical properties, antioxidant and antibacterial activity of the ZSEO-loaded microcapsules were investigated. The obtained emulsions with 6 wt% ZSEO showed a more homogeneous droplet size distribution (< 500 nm), long-term stability and higher viscosity, which were suitable for spray-drying microencapsulation. After spray drying, the ZSEO-loaded microcapsules had a smooth spherical structure and a homogenous size of around 10 μm. The moisture content, flowability, bulk density and encapsulation efficiency of microcapsules were improved by adjusting maltodextrin contents. Moreover, the ZSEO microcapsules with different maltodextrin contents had no significant impact on antioxidant capacity, and all ZSEO-loaded microcapsules performed excellent antibacterial activity. This study provides some guidance for the microencapsulation of spice essential oils, and improves their stability and applicability in the food industry.