Boosting the essential oil yield from the rhizomes of cassumunar ginger by an eco-friendly solvent-free microwave extraction combined with central composite design

This study aimed to apply the solvent-free microwave extraction (SFME) for isolating the essential oil from the rhizomes of cassumunar ginger and study the kinetic mechanism during the extraction process by light microscopy. A central composite design was employed to evaluate the influence of the key variables including microwave power and irradiation time on the oil recovery. The optimal process conditions of SFME were irradiation of the sample at 700W for 70min. Microwave power had the most significant effect on the oil recovery (p<0.001), followed by irradiation time (p<0.01). The major volatile constituents in the oil obtained under the optimal conditions were sabinene, terpinen-4-ol, and (E)-1-(3,4-dimethoxyphenyl) butadiene with a higher amount of the oxygenated compounds compared to those isolated by a conventional hydrodistillation (HD). Isolating the essential oil by SFME showed a complete extraction with higher plant cell rupture and was quicker than HD.