Study On Qualitative And Quantitative Analysis Of Star Anise Essential Oil Based On Electronic Nose

The purpose of this paper is to study an electronic nose analysis method which can qualitatively analyze the properties of essential oil and quantitatively analyze the content of components in essential oil.Therefore,for this purpose,the following studies are carried out.First of all,taking star anise essential oil as a sample,the best test conditions for the detection of star anise essential oil by electronic nose were explored and the methodology was investigated under these conditions.Then,the qualitative analysis of star anise essential oil extracted by different methods was studied by electronic nose(E-Nose),gas chromatography-mass spectrometry(GC-MS)and gas chromatography ion transfer spectrometry(GC-IMS).At the same time,the electronic nose characterized the quality of star anise essential oil under different storage conditions,qualitatively identified the star anise essential oil adulterated with base oil and sulfur fumigation,and quantitatively analyzed the star anise essential oil with different trans-anethole content.The purpose of this study is to provide reference for the feasibility of the application of electronic nose in the qualitative and quantitative study of essential oil.It was found that the best test conditions of star anise essential oil are as follows: the headspace formation time is 50 min,the injection volume is 2 m L,and the headspace formation temperature is 20 ℃.Under this condition,the methodology was investigated,and it was found that the response value RSD of each sensor is less than 3.5% in terms of repeatability,and,except for the S1 response value RSD of each sensor is 3.71%,while the response value RSD of the other sensors is less than 3.0% in terms of stability.The results show that each sensor has good stability and can meet the requirements of qualitative and quantitative detection of star anise essential oil.Star anise essential oil extracted by four methods(steam distillation,ethanol extraction,supercritical CO2 extraction and subcritical extraction)was studied by electronic nose,GCMS and GC-IMS.It was found that these three instruments combined with PCA analysis and LDA analysis can accurately distinguish star anise essential oil extracted by four methods and can be used as a rapid method to detect and distinguish star anise essential oil extracted by different methods.However,electronic nose and GC-IMS are more suitable for rapid identification of star anise essential oil extracted by different methods for simpler in operation,faster in analysis and lower in cost than GC-MS.The quality changes of star anise essential oil stored for different days under different storage conditions(room temperature open natural light,room temperature closed natural light,room temperature open light,room temperature closed light,refrigerator-4 ℃ closed light)were characterized.It was found that sensors S7 and S8 are sensitive to star anise essential oil under light conditions.The aroma components of star anise essential oil changed obviously in the first 30 days and 70-90 days after storage under different storage conditions.In addition,it was found that under the condition of closed light at room temperature and natural light at room temperature,the volatile matter will change obviously from the 70 th day to the 90 th day after storage,but it does not happen under the open condition.The PLS regression curves measured by electronic nose under different storage conditions were established,and the R2 values of the regression equations were all lower than 0.87.It shows that the PLS analysis model is not suitable to describe the storage days of star anise essential oil under different storage conditions.The difference of response value of electronic nose to star anise essential oil mixed with different vegetable oils is mainly reflected in S9 sensor and S7 sensor.The electronic nose can well distinguish star anise essential oils mixed with different vegetable oils(grape seed oil,tea seed oil,soybean salad oil,wheat germ oil,sweet almond oil,evening primrose oil and palm oil).Electronic nose combined with PCA analysis can well distinguish between sulfur-smoked star anise essential oil and unsulfur star anise essential oil.The electronic nose sensors S6,S8 and S7 are helpful to construct the linear relationship between the response values of trans anethole and electronic nose.The PLS regression equation is: y = 0.8329 x + 8.6104 R 2= 0.8939.It shows that electronic nose combined with PLS analysis can be used for quantitative analysis of trans-anethole in star anise essential oil,but the accuracy is not enough,it still needs to be improved in the later analysis.