Microwave-assisted ionic liquids treatment followed by hydro-distillation for the efficient isolation of essential oil from Fructus forsythiae seed

With the strong dissolution ability to biomaterials, ionic liquids can lead to a better release of the active and valuable ingredients embedded in plant matrices. Accordingly, an integrated microwave-assisted ionic liquids treatment followed by hydro-distillation (MILT-MHD) for isolating the essential oil from Fructus forsythiae seed was first performed in the present study. 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) was selected as the optimal ionic liquid. Operational conditions of this novel technique were optimized by the response surface methodology (RSM) and first order kinetic model. Compared with the conventional hydro-distillation (HD) and the emerging microwave-assisted aqueous ionic liquids hydro-distillation (MAILHD), the innovative MILT-MHD provided the remarkable advantage of much higher yield of essential oil (9.58%) within much shorter extraction duration (29.3 min) than those of HD (4.08% and 100 min) and MAILHD (5.43% and 45 min). Additionally, GC–MS results showed that higher contents of valuable oxygenated monoterpenes were existed in the essential oil obtained by MILT-MHD (22.79%) than those by HD (16.57%) and MAILHD (19.84%). Furthermore, SEM and FTIR results illustrated the severe structural disruption of seed samples by MILT-MHD. Therefore, the present results demonstrated that MILT-MHD is a potential, green and highly efficient technique for the extraction of volatile fractions from aromatic plant materials in the fragrance and flavor industries.

► An efficient MILT-MHD method was first developed for isolation of essential oil.
► Optimization and modeling the method by response surface design and kinetics.
► Procedure benefits: higher yield, shorter duration and more valuable constituents.
► Samples before and after treatment were characterized by SEM and FTIR spectra.
► A potential and green separation technique for the fragrance and flavor industries.