Studies On Extraction, Purification, Structure Identification And Micro-Encapsulation Of Chlorogenic Acid From Eucommia

Eucommia is a Chinese traditional cash crop, which is been concerned for its medicinal value. As a "food and medicine homologous" green natural plant, with the function of cholagogue, antihypertensive, anti-bacterial, anti-inflammatory and pharmacological effects such as elevated white blood cells, Eucommia is an important renewable resource. Chlorogenic acid (CA, phenolic acid condensated by caffeic acid and quinic acid) is an important active ingredient of Eucommia ulmoides. In this study, the subject is focus on extraction, purification, identification, micro-capsulation of CA and preparation of Eucommia tea yogurt. CA in this study was produced in Hubei, modern separation method and micro-capsulation technology were performed in this study. Micro-capsulation of CA by yeast cell wall could increase the stability of CA, providing a favorable solution for the storage of CA products. A new type of health-based Eucommia tea yogurt was developed through process optimization. The main results were shown as follows:1 Extraction of CA from EucommiaThe CA of Eucommia leaf from Hubei Xiangfan region was extracted using ethanol ultrasonic. By single factor and orthogonal experiments, we obtained the optimum extraction conditions:ethanol concentration 60%, temperature 60℃, solid-liquid ratio 1:20, pH 3, and the maximum extraction rate reached 6.1%2 Purification and identification of CABy screening of NKA-2,NKA-9,AB-8,XD-2,D14,D16,SIPI-DA201 macroporous resin to purify CA, the results indicated that NKA-2 macroporous resin was optimum for the CA purification, its adsorption and desorption rate were 99.67%, and 62.8%, and the optimum elution reagent was 30%ethanol with HCl (pH3). Ethyl acetate was used to extract flavonoids from crude extracts, and then NKA-2 resin used for gradient elution to obtain CA with purity of 76.3%. HPLC-MS analysis results showd that CA was condensated by caffeic acid and quinic acid.3 Comparison of the antioxidant activity between Eucommia extraction and pure CAThe reduction force, clearance rate of·OH and superoxide anion of Eucommia extraction and pure CA were determined by K3[Fe(CN)6], fenton method, pyrogallol self oxidate respectively, and VC was used as the control. The results showed that the antioxidant properties of Eucommia extraction were higher than pure CA, while the Vc had the strongest scavenging capacity on superoxide anions which could reach 100%.4 Yeast-cell-based micro-encapsulation of CAThe cell wall of Saccharomyces cerevisiae was used to encapsulate the water-soluble CA. The effects of encapsulating temperature, time, the mass ratio of chlorogenic acid to the cell wall and other factors were investigated by orthogonal experiment design. Under the conditions of using 6ml double-distilled water to dissolve the mixture, mass ratio between CA and yeast cells was 3:1, soaking the mixture in the water at 40℃for 6 h, the maximum encapsulation efficiency reached 18.9%. The infrared spectrum analysis of microencapsulation showed that the vibration of characteristic radical of CA disappeared. The fluorescence image of microcapsules has shown the microcapsules were spherical and spontaneous fluorescence of CA can be observed in the inner side of cell wall. The same retention time and UV-Vis figure between the standard and microencapsuled CA were found through HPLC analysis. All the results suggested that CA has been successfully encapsulated and no chemical changes had taken place during the encapsulation process.5 Preparation of Eucommia tea yogurt and the effects of tea powder on yogurt qualityUsing milk and Eucommia tea powder as the main materials, the functional tea yogurt combining of tea powder and yogurt were prepared by fermentation with Lactobacillus bacteria. The effects of the amount of tea powder, white sugar, inoculum, and stabilizer on yogurt quality were investigated by orthogonal experiment design. The present study showed that the optimal conditions were:Eucommia tea powder 0.15%, white sugar 6%, inoculum 8%, stabilizer 0.1%. Both the Eucommia tea powder and pure chlorogenic acid could affect the quality of yogurt, and the results indicated that Eucommia tea powder which contained complex ingredients could promote the fermentation of Lactobacillus bacteria, while the effect of chlorogenic acid was on the opposite. Adding eucommia tea powder to yogurt had no negative effects on yogurt quality and its protein exosomatic digestibility.