Discovery of Quality\nby Design-Based Extraction Technology\nand the Quality Standard of Jinhua Finger Citron Essential Oil

Jinhua finger citron is one of the traditional specialties\nof Jinhua\nwith a long history of cultivation. The current study highlighted\nthe advantages of using the quality by design approach to optimize\nthe ultrasonic-assisted distillation extraction of Jinhua finger citron\nessential oil. The yield of Jinhua finger citron essential oil was\nregarded as a potential critical quality attribute. Potential critical\nprocess parameters were screened by the definitive screening design.\nFinally, the design space of the essential oil extraction process\nwas constructed. The optimal operating space included an auxiliary\nNaCl concentration range of 9–12.00%, a soak temperature range\nof 30–50 °C, a distillation time range of 3.5–4.00\nh, an ultrasonic power range of 200–300 W, a solid–liquid\nratio range of 1:3–1:3.5, and a soak time range of 40–80\nmin. On this basis, the relative density, refractive index, and pH\nvalues of different batches of Jinhua finger citron essential oil\nwere checked. The involved batches were analyzed by gas chromatography\n(GC), and gas chromatographic fingerprints were established by identifying\nmajor compounds, including d-limonene, γ-terpinene,\nand 5,7-dimethoxycoumarin. Based on the “quality by design”\nstrategy, the extraction process of Jinhua finger citron essential\noil established in this study was robust, reliable, and flexible.