“紫娟”晒青绿茶色素的HPLC-ESI-MS分离鉴定及其稳定性研究

HPLC-ESI-MS Analysis of Pigments in Zijuan Green Tea and Its Stability

研究"紫娟"晒青绿茶主要呈色成分及其稳定性。采用酸性甲醇-水和水分别提取"紫娟"晒青绿茶色素,利用HPLC-ESI-MS/MS方法对其主要色素进行了分离鉴定。结果显示,"紫娟"晒青绿茶含有14种花色素苷、24种黄酮、8种酚类以及3种生物碱。主要的花色苷类物质为天竺葵素-3-葡萄糖苷或天竺葵素-3-半乳糖苷、天竺葵素-3-(6-香豆酰基)-葡萄糖苷、飞燕草素-3-葡萄糖苷、飞燕草素-3-芸香糖苷、飞燕草素-3-O-(6-香豆酰基)-葡萄糖苷、Prodelphinidin B-2(or 4)3′-O-gallate、Procyanidin B-2(or 4)3′-O-gallate、Petunidin-3-glc-4-vinylphenol和Malvidin-3-glc-4-vinylepicatechin等。酸性甲醇-水提取的"紫娟"晒青绿茶红色素水溶性好,颜色随pH值变化而变化。酸性条件下该色素对光、低温有很好的稳定性,耐氧化性与耐还原性较强。Cu2+、Fe3+使色素稳定性变差。明确了"紫娟"晒青绿茶呈现紫色的主要物质基础。

The pigments and its stability in Zijuan sun-dried green tea were investigated in this study. The pigments from Zijuan sun-dried green tea were extracted by acidic methanol-H2O solution and H2O, and the main compounds were identified by means of HPLC-ESI-MS/MS techniques. 14 anthocyanin, 24 flavonols, 8 phenolics and theaflavins and 3 alkaloids were identified from the extracts of Zijuan sun-dried green tea. The main anthocyanins, such as Cyanidin-3-glucoside, Cyaniding-3-galactoside, Cyanidin-3-O-（6-p-coumaroyl）-glucoside, Delphinidin-3- glucoside, Delphinidin-3-rutinoside, Delphinidin-3-O-（6-p-coumaroyl）-glucoside, Prodelphinidin B-2（or 4）3＇-0- gallate, Procyanidin B-2（or 4）3＇-O-gallate, Petunidin-3-glc-4-vinylphenol and Malvidin-3-glc-4- vinytepicatechin etc were identified in Zijuan sun-dried green tea. The pigment extracted from Zijuan sun-dried green tea by using acidic methanol-methanol-H2O as solvent showed good water-solubility and was stable to light and heat in acid environment, but sensitive to the pH value of environment, oxidizer and reducer. The maximum adsorption wavelength for the pigment is 538nm under pH 1.0. Fe2＋ and Cu2＋ can change the color of the pigments and stability was decreased. The substance of the purple colour in Zijuan sun-dried green tea was clarified by HPLC-ESI-MS/MS analysis.