绿茶面包中儿茶素总量检测方法研究

儿茶素是茶叶的主要功能成分,本试验探讨了乙醇浸提、硫酸-香荚兰素比色法检测绿茶面包中儿茶素含量的可行性.选择95％乙醇溶液作为提取溶剂,采用3因素3水平正交试验设计方案,考察料液比、浸提温度、浸提时间对绿茶面包中儿茶素总量提取效果的影响,并对硫酸-香荚兰素比色法检测绿茶面包中儿茶素含量进行了方法学考察.结果表明,绿茶面包中儿茶素总量检测的最佳浸提条件为:料液比1:20(g·mL-1),70℃水浴浸提45 min;硫酸-香荚兰素比色方法为:取0.5 mL浸提液,加入2.5 mL1％的香荚兰素/乙醇溶液和2.5 mL30％的硫酸/乙醇溶液,在20℃下反应10～30 min,取反应液在500 nm处测定吸光度.本方法中儿茶素浓度在0.025～0.3 mg·mL-1范围内,吸光度与浓度线性关系良好(R2=0.9996),同一样品重复测定6次的RSD为1.31％,儿茶素高、中、低浓度加标回收率范围在98.75％～103.25％,本方法满足绿茶面包中儿茶素总量的检测分析,儿茶素含量可作为标定绿茶面包中茶叶添加量的评价指标.

Determination of Total Catechins in Green Tea Bread

An assay method was established for the determination of total catechins,the major functional component of tea,in bread made with ultrafine green tea powder as an ingredient.The method was optimized with a 3-factor(i.e.,solid-liquid ratio,extraction temperature,and extraction time)and 3-level orthogonal experiment for the 95%ethanol extraction prior to a colorimetric measurement after the sulfuric acid-vanillin reaction.The optimized ethanol extraction was conducted under a solid-liquid ratio of 1:20(g·mL^-1)in a 70℃water bath for 45m.Subsequently,0.5 mL of the extract were added with 2.5 mL each of 1%vanillin and 30%sulfuric acid ethanol solutions to stand at 20℃for 10~30 min.Spectrophotometric absorbance at 500 nm of the reaction solution was obtained.The readings were found correlated linearly with the standard catechins concentrations in the range of 0.025~0.3 mg·mL^-1 with a R² of 0.9996.The RSD of 6 replicates measured by the new method was 1.31%.And,the catechins recovery at high-to-low concentrations ranged from 98.75%to 103.25%.The method appeared appropriate for the total catechins determination in bread containing green tea.