【作者】 卢琪；

【导师】 潘思轶；

【作者基本信息】 华中农业大学 ， 食品科学， 2010， 硕士

【摘要】 杜仲是我国的传统的经济作物,其药用价值一直备受关注。作为天然的绿色植物,具有利胆、降压、抗菌、消炎及升高白细胞等药理作用,是一种重要的可再生资源。其中绿原酸(咖啡酸和奎尼酸缩合的缩酚酸)是杜仲中重要的活性成分。本研究课题是对杜仲叶中的绿原酸进行提取、分离纯化、结构鉴定、微胶囊及杜仲茶酸奶功能性酸奶的研究。本文以湖北老龙洞杜仲开发有限公司提供的杜仲叶为主要原料,利用现代化的分离手段和新型的微胶囊化技术对杜仲叶中的绿原酸进行研究。通过酵母细胞壁包埋绿原酸可提高绿原酸的稳定性,为绿原酸类保健品的贮藏提供有利的方案。同时,对杜仲茶酸奶的研制工艺进行优化,研制出新型的保健型杜仲茶酸奶。本实验所得主要结果如下：1杜仲绿原酸的提取以湖北襄樊地区的杜仲叶为原料,采用乙醇超声提取杜仲叶中的绿原酸。通过单因素实验,正交实验确定最佳提取条件,研究表明,在乙醇浓度为60%、提取温度60℃、料液比为1：20、提取液的pH值为3的条件下,杜仲叶中绿原酸的提取率达到最大,为6.1%。2杜仲绿原酸的分离纯化及结构鉴定对NKA-2、NKA-9、AB-8、XD-2、D14、D16、SIPI-DA201七种大孔树脂进行筛选,NKA-2型大孔树脂对绿原酸有较好的选择性,其吸附率和解吸率分别为99.67%和62.8%。盐酸调整洗脱液的pH为3,洗脱液的浓度为30%时,洗脱效果最好。澄清后的绿原酸粗提液经乙酸乙酯萃取除去黄酮,再用NKA-2型树脂进行梯度洗脱,可得到纯度为76.3%的绿原酸。HPLC-MS分析表明,绿原酸是咖啡酸和奎尼酸缩合的缩酚酸。3杜仲提取物和绿原酸纯品抗氧化活性的对比分别采用K3[Fe(CN)6]、Fenton法、邻苯三酚自氧法测定杜仲提取物和绿原酸纯品的还原力、对·OH的清除率,对超氧阴离子的清除率,并以Vc最参照。结果表明：杜仲提取物的各项抗氧化性能均高于绿原酸纯品,而Vc对超氧阴离子的清除能力最强可达到100%。4绿原酸酵母细胞微胶囊化的研究采用酿酒酵母的细胞壁包埋水溶性的绿原酸,通过正交试验考察包埋温度、包埋时间、芯材比等因素对绿原酸微胶囊包埋率的影响。结果表明,在包埋温度40℃、包埋时间6h、芯材比为3：1(g／g),以6mL蒸馏水为包埋介质的组合条件下,包埋率最大为18.9%。微胶囊红外光谱分析发现绿原酸的特征官能团的振动消失；荧光显微镜观察显示微胶囊呈球形,微胶囊内的绿原酸自发明亮的荧光；高效液相色谱定性分析显示,绿原酸包埋前后保留时间及紫外扫描图谱相一致。研究结果表明绿原酸成功的包埋到酵母细胞壁内,且在包埋过程中没有发生任何化学变化。5杜仲茶酸奶的研制及茶粉对酸奶品质的影响以牛乳和杜仲茶粉为主要原料,经乳酸菌发酵后,制成茶粉与酸奶结合的功能性新型酸奶。通过正交实验考察了杜仲茶粉添加量、加糖量、接种量和稳定剂的添加量对酸奶品质的影响。结果表明,当杜仲茶粉添加量0.15%、白砂糖添加量6%、发酵剂接种量8%、稳定剂添加量0.1%时,酸奶色泽、香气、滋味及组织状态具佳。杜仲茶粉和杜仲绿原酸纯品均能影响酸奶的发酵品质,实验结果表明成分复杂的杜仲茶粉能够促进乳酸菌的发酵产酸,而纯品绿原酸则有抑制作用；杜仲茶粉的添加对酸奶品质及蛋白质体外消化率无不良影响。更多还原

【Abstract】 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.更多还原