Research On Extraction,Chemical Composition Analysis And Supercritical CO₂ Extraction Kinetics Of Vetiver Essential Oil

Vetiver（ Vetiveria zizanioides（Linn.） Nash）is an excellent industrial crop separating widely in China. Its developed root system contains large amounts of essential oil. The vetiver oil has a variety of biological active components which has been broadly used in the field of perfume and daily chemical products,food and beverage industry, medical care industry, etc. The market requirement of vetiver oil is large while the price is high, so it has an important practical meaning to develop the resource of vetiver oil extensively. The thesis mainly completed the following aspects of research:（1） Extracting vetiver oil through Microwave-Assisted Soxhlet Extraction（MASE） and optimized extraction process by single-factor experiments and quadratic general rotary unitized design experiments, while setting the yield of vetiver oil as the experimental target. The optimized conditions of the MASE extraction were as follows: acetone as the solvent; microwave treatment time: 4.14min; solid-liquid ratio: 1:41 g/mL; extraction time: 3.13 h. Under these conditions,the yield of vetiver oil was 6.91%. The sequence of the factors significance level were as follows: solid-liquid ratio> microwave treatment time> extraction time.Besides, microwave treatment time and solid-liquid ratio had strong interaction.（2） Extracting vetiver oil by Supercritical Carbon Dioxide Fluid Extraction（SCFE-CO₂） and optimized extraction process by single-factor experiments and response surface methodology（RSM）, while setting the yield of vetiver essential oil as the experimental target. The optimized conditions of the SCFE-CO₂ extraction were as bellow: grinding granularity: 60⁸0 mesh; volume charge coefficient: 0.8;extraction pressure: 22.6 MPa; extraction temperature: 35.4 ℃; CO₂ flow rate: 1.6L/min; extraction time: 1.5 h. Under these conditions, the yield of vetiver essential oil is 7.76%. The sequence of the factors significance level were as follows:extraction pressure > CO₂ flow rate > extraction temperature. Besides, extractiontemperature and CO₂ flow rate had strong interaction.（3） Using national standard method to analyze the physical and chemical properties of three kinds of vetiver oil extracted by different methods（ hydro distillation, solvent extraction and SCFE-CO₂）. The results indicated that the physical and chemical properties of the three vetiver oil all meet the international standards. Among the three extraction methods, SCFE-CO₂ was better than the other two extraction methods in some critical physical and chemical properties, such as the yield of vetiver oil, sensory evaluation, acid value and ester value, etc.（4） Using gas chromatography-mass spectroscopy method（GC-MS） to compare and analyze the components of vetiver oil extracted by the three extraction methods. The result showed that different extraction methods had influence on components and content of vetiver oil. Among them, vetiver oil extracted by SCFE-CO₂ had the most abundant of components. A total of 28 main compounds were identified in vetiver oil. sesquiterpenoids and its derivatives were the major compounds, and most of them belong to the category of alcohol, ketone and alkene.Furthermore, the part also analyzed the application prospects of vetiver oil’s main components in the field of biomedicine, food additives, perfume, etc.（5） The Broken and intact cells（BIC） theory were adopted to simulate and calculate the SCFE process of vetiver oil under different temperatures and pressures. Given on the basis, an extraction dynamic model was established. The values of average absolute relative deviation（AARD） of the model were in range of 1.16%⁷.54%,indicating that the dynamic model had good simulation results. The parameters of the model had clear physical meanings which could explain the experimental phenomena well and also had guiding significance to the further magnification experiments.