Microencapsulation of Mentha spicata essential oil by spray drying: Optimization, characterization, release kinetics of essential oil from microcapsules in food models

The aim of this study was to optimize microencapsulation conditions of spearmint essential oil (SEO) by spray drying, using a blend of inulin and gum Arabic as wall material. The oil retention, encapsulation efficacy, hygroscopicity, and carvone content were investigated with respect to three variables, including total solid content (x1), oil concentration (x2) and inlet air temperature (x3) via response surface methodology (RSM). The optimal conditions were (35 % solid wall, 4% essential oil concentration, and 110 °C inlet temperature) with maximum oil retention 91.0 %. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were confirmed that SEO was encapsulated without any chemical interaction. Release study of produced powder at the optimized process conditions was evaluated by four food simulants (distillated water, 10 % ethanol, 50 % ethanol, and 3% acetic acid). Mechanism of SEO release was demonstrated by first order, Korsmeyer-Peppas, Higuchi, and Peppas-Sahlin models. The Peppas-Sahlin model was found as the best approach for SEO release profile, and the release phenomenon was mostly governed by Fickian diffusion in four food models. Considering the successful encapsulation of SEO, the nature of the prebiotics wall, and its fast release, this powder can be used in the food and pharmaceutical industries.