Encapsulation of oregano essential oil (Origanum vulgare) by complex coacervation between gelatin and chia mucilage and its properties after spray drying

Abstract

Oregano essential oil (OEO) was encapsulated by complex coacervation between gelatin and chia mucilage (mass ratio 2:1, solids concentration 0.2% w/w). It was compared with a system of gelatin-arabic gum (GE-GA) as encapsulating agents. Two essential oil concentrations (5 and 7.5% w/w) were studied to determine its effect in the formation of complex coacervates by its encapsulation efficiency (EE). To characterize the complex coacervates Fourier-transform infrared spectroscopy (FTIR), particle size and morphology were determined. FTIR spectrum of complex coacervates showed characteristics peaks of carvacrol, one of the majority components present in OEO. OEO concentration and emulsifier added influenced the particle size and morphology of the coacervates, being the sample with gelatin-chia mucilage (GE-ChM) and 7.5% of OEO, the complex with the highest EE obtained (91.79 ± 0.05%). Complex coacervates with the highest EE were spray dried, testing two inlet temperatures (180 and 160 °C) and two feeding rates (5 and 7.5 g/min). Dried coacervates were characterized in moisture content, solid yield, EE, particle size, bulk density, tapped density, compressibility index, and Hausner ratio. Inlet temperature and feeding rate affected the physical properties studied, being the sample with GE-ChM (160 °C and 5 g/min) the one with the highest encapsulation efficiency observed (95.6 ± 0.39%). Moreover, GE-ChM powders had the best flow properties (compressibility index and Hausner ratio). Therefore, GE-ChM resulted in a better system than GE-GA to encapsulate OEO, being an alternative as encapsulating agents.