Study on the Process of Extracting Patchouli Essential Oil by Steam Distillation

To enhance the extraction efficiency of patchouli essential oil via steam distillation, this study systematically investigated the effects of key process parameters on extraction yield. Single-factor experiments were first conducted to analyze the influence of distillation time, solid-liquid ratio, soaking time, and raw material particle size on overall mass transfer performance during extraction. After determining the optimal ranges for each parameter, the three significantly influential variables—distillation time, solid-liquid ratio, and soaking time—were selected for focused optimization. A Box–Behnken design combined with response surface methodology was employed to construct a quadratic polynomial regression model describing the individual and interactive effects of these parameters on essential oil yield. Statistical analysis confirmed the model's high predictive accuracy, with all factors exhibiting significant individual and interactive effects. The response surface optimization yielded optimal extraction conditions: distillation time of 130 minutes, solid-to-liquid ratio of 1:18 g/mL, maceration time of 88 minutes, and a fixed raw material particle size of 0.2 mm to ensure stable heat and mass transfer conditions. Under these optimized conditions, the actual patchouli essential oil yield reached 3.87% (w/w), closely matching the predicted value and validating the model's reliability and practicality. These findings provide scientific basis and technical guidance for enhancing steam distillation efficiency, holding positive implications for advancing the industrial production of patchouli essential oil in fragrance, pharmaceutical, and cosmetic sectors.