Study On New Technologies For Separation And Analysis Of Essential Oil In Chuju

Chuju is one of the most famous chrysanthemums in China, which has antiviral, antioxidant and antimyocardial ischemia activities. Essential oil is the effective constituent of Chuju. Conventional extration methods of essential oil including hydrodistillation and simultaneous have some defects including low efficiency and degradation of unsaturated compounds. Besides, one-dimensional gas chromatography was far from sufficient separation for a complete qualitative, let alone, quantitative analysis. Therefore, it is required to develop a new method to achieve improved analysis. Glycoside have been known as important precursors which can contribute to improvement of aroma of plant. Therefore, analysis on the existence and distribution of glycosides in chrysanthemums can be important guidance to the production and processing of chrysanthemums products.In this paper, comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOF/MS) combined with supercritical carbon dioxide extraction (SFE) was used for analysis of essential oil from flower of Chuju. The essential oil obtained by SFE were purified by molecular distillation (MD) to improve the concentration of bioactive components. New analytical technology, GC× GC-TOF/MS, was adopted to built a new method for the analysis of glycoside in morifolium. Four cultivars chrysanthemums in China (Chuju, Boju, Hangbaiju, Gongju) were tested by the newly-established method and the difference of glycoside between four cultivars were discussed. The main work of this thesis is summarized as follows:Firstly, GC×GC-TOF/MS was combined with SFE to established a new method for analysis of essential oil from Chuju. The effect of SFE five different parameters on the extraction yield was investigated. Under the optimal conditions, the essential oil yield was 6.40%. A total of 92 compounds have been identified by GC×GC-TOF/MS. Terpenes were the main components which accounted for 66.74% of the identified volatile compounds. The result indicated SFE was efficient in extracting bioactive terpenes and their oxygenated compounds. Compared with traditional GC-MS, GC× GC-TOF/MS was better in separation and more suitable for analysis of essential oil. In addition, three important floral aroma C13-norisoprenoids were firstly found in Dendranthema morifolium.Secondly, MD was used to refine the essential oil obtained by SFE with the aim to improve the contents of bioactve compounds. The effect of MD process parameters including distillation pressure, distillation temperature, and feed rate on the extraction yield and contents of bioactve compounds was investigated. The distillates were analyzed by GC×GC-TOF/MS. At the same time, the distillates were added into cigarettes as flavors, and sensory evaluation was conducted. The result showed optimal distillation process parameters of MD were 100 Pa pressure,120℃ temperature and 2 mL/min feed rate. Under such conditions, the yield of distillate was 20.80%, and the content of terpenoids was increased from 52.81 mg/g to 330.40 mg/g. The result of sensory evaluation indicated the addition of distillates of essential oil from Chuju effectively increased aroma quality of cigarette smoke, reduce undesirable taste, improve the mildness and smoothness. It can be used as a good natural cigarette flavor.Thirdly, a simple enzymatic hydrolysis method of determination of glycosidically bounded aroma compounds in Flos Chrysanthemi using GC× GC-TOF/MS was established. After isolation from sample by extraction, glycosides in four cultivars of Flos Chrysanthemi (Chuju, Boju, Hangbaiju, Gongju)were analyzed after enzymatic hydrolysis by GC×GC-TOF/MS. A total of 60 aglycones have been determinated in Chinese four cultivars of Flos Chrysanthemi. The result indicated that the amount of glycoside in four Flos Chrysanthemi is highly positive correlated with their floral odor levels. Two Flos Chrysanthemi used for tea drinks (Hangbaiju and Gongju) released more flavor compounds which mainly benzene derivatives and C13-norisoprenoids. Meanwhile the result of principal components analysis showed phenylethyl alcohol and 3-oxo-a-ionol were the main contribution components to the floral fragrance of two Flos Chrysanthemi used for tea drinks. The result of this study reveals the chemical basis of the different flavor characteristics and usage of each cultivars in the term of glycosides.