An improved approach of salting-out solvent-free microwave mediated rotary distillation for essential oil preparation from fresh leaves of magnolia (Oyama sieboldii)

An improved method denoted as salting out-solvent-free microwave rotary distillation (SOSFMRD) was successfully developed for the extraction of essential oils from fresh magnolia ( Oyama sieboldii ) leaves, in which we achieved the rotation of the reaction material by means of a rotating motor to subject the material to uniform microwave irradiation. Magnesium chloride was selected as the salting-out agent through a comparative study on the salting-out effects of different anions and cations of metal salts. The variables of SOSFMRD were systematically optimized. Under the obtained optimization conditions, the essential oil yield was 21.68 ± 1.02 mL/kgDW. Gas chromatography–mass spectrometry analysis showed that the main chemical constituent of O. sieboldii essential oil was dehydrocostuslactone, the content of which reached 30.23 ± 1.27 %. Compared with the other conventional methods, this method has a high yield and low energy consumption, which can effectively reduce impact on the environment.