Abstract: A kinetic model was established to study the extraction kinetics of lavender essential oil under vacuum steam distillation. Gas chromatography-mass spectrometry (GC-MS) was used to analyze and measure the dynamic content changes in the main components, i.e., linalool andlinalyl acetate, during the extraction process, and to compare the quality of essential oils obtained at different distillation times. Results show that the dynamic model of the lavender essential oil extraction process under vacuum steam distillation was y=4.292 5(1-e^{-0.017 9x}). GC-MS analysis revealed 48 volatile components in the oil, where linalool, linalyl acetate, etc. were the main volatile components. With the extension of extraction time, the linalool content decreased from 49.51% to 16.78%, with a significant downward trend. The experiment revealed that the kinetic model can appropriately simulate the law of essential oil extraction process. Combined with the analysis of essential oil quality, the extraction rate of lavender essential oil under reduced pressure for the first 120 min reached 1.88% and the components were basically stable. Subsequently, the extraction rate increased more slowly, the main component linalool decreased significantly, and the components became more complicated. This research suggests that the optimal time for extraction of lavender essential oil is 120 min, which can ensure a high extraction rate, obtain goodquality essential oils, and save extraction time.

Key words: vacuum steam distillation, lavender, essential oil, kinetic investigation