| In the high-pressure,fast-paced life,most people are in a sub-healthy state,and traditional Chinese medicine has comprehensive curative effects,applied in the medical model of prevention,health care,treatment,and rehabilitation.Traditional medicine is a broad and profound subject with thousands of types and Polygonum cuspidatum is one of them.It has a history of thousands of years of application and has excellent edible and medicinal effects.Many studies have shown that it has great medicinal value and its active ingredients such as resveratrol and emodin are widely applied in the fields of medical treatment,health care,cosmetics,and food,due to their excellent antioxidant properties,antibacterial,anti-inflammatory,hepatoprotective and choleretic effects,etc.In this thesis,supercritical CO2extraction technology was used to extracted the resveratrol and emodin from the traditional Chinese medicine Polygonum cuspidatum.The extraction process was optimized and modeled,which provided a theoretical basis for the development of industrialization.This study focused on the following four aspects:（1）In order to explore the influence of extraction temperature,extraction pressure,ethanol volume ratio,and extraction time on the yields of resveratrol and emodin,the single-factor experiment was performed to obtain the best extraction conditions:50℃,25 MPa,100 ml/L,60 min.In addition,the UV spectrophotometry was established by changing the p H of the system and the dual-wavelength first derivative method to achieve the simultaneous detection of the content of resveratrol and emodin.The standard curves of the them were obtained and R2was 0.9996 and0.9999,respectively.In addition,the test of precision and experiment of sample recovery proved that this method had good repeatability and accuracy.（2）Based on the principle of conservation of differential mass,the extraction process of Polygonum cuspidatum was numerically simulated.Partial differential equations were established and simplified,combining with a series of hypotheses of extraction process.Using the software of Matlab as the platform,the parameters of model were calculated and numerical methods were used to solve the equations,combining with the boundary and initial conditions.Additionally,the value of KfA was continuously optimized using the trial-and-error method to achieve the highest agreement between simulated values and experimental date.The yields of resveratrol with extraction time under the different pressures and ethanol contents at 313 K were simulated.The calculated values had a high consistency with the experimental spots,thus verifying the reliability and accuracy of the model.（3）The response surface method（RSM）was used to further optimize the supercritical extraction process of Polygonum cuspidatum.The independent factors were selected as temperature（45-55℃）,pressure（20-30 MPa）,ethanol content（80-120 ml/L）.Through the analysis of regression and variance,the optimal extraction conditions was obtained（i.e.,the temperature of 51.83℃,the pressure of25.34 MPa,and the ethanol contents of 110.83 ml/L）.Under the conditions,the confirmatory experiment was carried out and the yields of resveratrol and emodin were 2.564±0.121mg/g and 2.804±0.108mg/g,which was consistent with the simulated values.（4）Exploring the performance of extracts under the optimal extraction conditions,the determination of oil POV value,thermal and light stability tests were carried out,which showed that the extracts could well inhibit the process of peroxidation reaction,and resveratrol、emodin should be stored in the dark,especially resveratrol was suggested to be stored below 65℃.The researches on DPPH and ABTS free radical scavenging ability,reduction and total oxidation capacity illustrated that the extracts was better than BHT due to their great free radical scavenging ability and outstanding reduction and total oxidation ability,which mutually proved that the extracts had strong anti-oxidation ability. |
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