Ultrasonic pretreatment combined with microwave-assisted hydrodistillation for the situ extraction of essential oil from Pinus koraiensis seed scales induced by tea saponin: Functional activity, composition, thermal stability and material characterization

In this work, in situ extraction of essential oil from Pinus koraiensis seed scales using tea saponin-induced ultrasonic pretreatment-microwave-assisted hydrodistillation (UP-MAHD) was studied. By fitting the extraction kinetic curves with different factors, a first-order kinetic model was determined to be more suitable. The key factors were screened and optimized via PlackettBurman Design (PBD) and BOX-Behnken Design (BBD). Under the optimization parameters of a liquid material ratio of 14 mL/g, power of 100 W, time of 15 min, temperature of 50 °C, and tea saponin dose of 0.4% for the ultrasonication and then microwave at 458 W for 18 min, the actual yield was 8.02 μL/g± 0.35% and was highly consistent with the theoretical yield of 8.21 μL/g. UP-MAHD-treated Pinus koraiensis seed scales essential oil (PKSSEO) had good inhibition functional activity of α-amylase. In addition, the chemical composition of the PKSSEO were determined using Gas chromatographymass spectrometry (GCMS) and Fourier transform infrared spectroscopy (FT IR), thermal gravimetry (TG), and differential scanning calorimetry (DSC), and its spatial structure characterization (SSC) obtained via UP-MAHD treatment was enhanced. In summary, this extraction method efficiently extracted PKSSEO with a lower effect on its activity and composition and could have solid future development prospects. Our study provided effective theoretical data support for the reuse and development of abandoned Pinus koraiensis seed scales resources.