摘要
黄酮类与儿茶素类物质对茶叶感官品质和生物活性起重要作用,因此建立一种茶叶中总黄酮(包括黄酮类和儿茶素类)含量的测定方法很有必要。采用70%甲醇提取茶样,以芦丁为对照品,利用亚硝酸钠-硝酸铝-氢氧化钠溶液显色,在510 nm下测定吸光度,建立测定茶叶中总黄酮含量的分光光度法,并对其进行方法学考察。应用该法测定了绿茶、白茶、乌龙茶和红茶4个茶类15个茶样中总黄酮含量,采用福林酚法测定其茶多酚含量,并比较二者相关性。结果表明,芦丁质量浓度在0.2~1.0 mg·mL^(-1)范围内与吸光度线性关系良好,回归方程为Y=1.2465X+0.0074(R^(2)=0.9997)。方法学考察结果表明,该方法精密度、重复性和稳定性的吸光度RSD为1.17%、2.92%和6.01%,平均加标回收率为84.35%(RSD=4.15%)。15个茶样中总黄酮含量范围为5%~10%,总黄酮含量规律为:绿茶、白茶>乌龙茶>红茶。福林酚比色法测得茶多酚含量范围为7%~15%。双变量相关性分析显示,总黄酮含量与茶多酚含量呈极显著正相关,Pearson相关系数达0.874。由此表明,该方法操作简便,精密度、重复性与稳定性好,可用于茶叶总黄酮含量测定。
Flavones and catechins are critical chemicals associated with the sensory quality and biological activity of tea.This study aimed to establish an applicable method for the determination of total flavonoids in teas.Specimens of commercially available teas of different types were extracted with 70%methanol followed by colorization with a NaNO2-Al(NO3)3-NaOH solution.Using rutin as the reference,a spectrophotometric method for absorbance measurements at 510nm was established and validated.For comparison,the polyphenol contents in 15 samples of green,white,oolong,and black teas were determined at the same time by the Folin-Ciocalteu method.A high linear correlation on the total flavonoids measured by the absorbance was found in the rutin concentration range of 0.2-1.0 mg·mL^(-1) with the regression equation of Y=1.2465X+0.0074(R^(2)=0.9997).The newly developed spectrophotometric method showed RSDs on the measurement precision at 1.17%,on the repeatability at 2.92%,on the stability at 6.01%,and on the 84.35%average recovery rate of spiked standards at 4.15%.The flavonoid contents in the 15 samples ranged from 5%to 10%,and polyphenols from 7%to 15%.The total flavonoids contents in the 4 tea types ranked as green tea/white tea>oolong tea>black tea.A bivariate correlation analysis showed that the content of total flavonoids positively correlated to that of tea polyphenols with a Pearson correlation coefficient of 0.874.The proposed methodology was deemed simple,precise,repeatable,and stable for the total flavonoids determination on teas.
作者
王丽丽
林清霞
宋振硕
陈林
WANG Li-li;LIN Qing-xia;SONG Zhen-shuo;CHEN Lin(Tea Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou Fujian, 350013, China)
出处
《茶叶学报》
2021年第1期1-6,共6页
Acta Tea Sinica
基金
福建省属公益类科研院所基本科研专项(2020R1029006)。
关键词
茶
总黄酮
黄酮类
儿茶素
含量测定
显色
分光光度法
Tea
total flavonoids
flavones
catechins
determination
coloration
spectrophotometry
