信阳毛尖茶指纹图谱分级标准样品的研制方法

Development of Certified Reference Materials for Xinyang Maojian Tea Grading Based on HPLC Fingerprints of Flavor Components

建立一套基于指纹图谱分级的茶叶标准样品研制方法,研制3个级别(120个样,每样50 g)的信阳毛尖茶标准样品。依据国标方法制备茶汤,采用高效液相色谱法进行茶汤滋味成分指纹图谱分析,并采用新改良程度相似度法进行相似度计算。以指纹图谱的相似度作为评价指标,按照《标准样品工作导则》的要求,对所研制标准样品进行均匀性检验(F检验)、稳定性检验(t检验)和8家实验室联合定值。结果表明,所研制的各级茶样均匀性、稳定性良好,对各级茶样的指纹图谱相似度的定值结果和不确定度(95%置信度)分别为0.918±0.027(一级)、0.662±0.033(二级)、0.400±0.074(三级),且与感官评审等级一致。该标准样品具有量化分级的特征,是国内首套指纹图谱分级茶叶标准样品。已获得全国标准样品技术委员会颁发的有证标准样品证书,可用于信阳毛尖茶的分等定级。

A method of developing tea reference materials(RMs) to be used in tea grading based on fingerprint classification was established in this paper, and three grades(120 samples, 50 g each) of Xinyang Maojian tea certified reference materials(CRMs) were developed. Tea infusion samples were prepared according to the national standard, and then analyzed by HPLC for flavor ingredients. A newly improved extent similarity method was used for calculation of fingerprint similarity.On the basis of the fingerprint similarity, the homogeneity and stability of the tea RMs were tested and similarity values were certified by eight laboratories according to the guidelines for CRMs. The results indicated that each grade of samples had good homogeneity and stability. The fingerprint similarity value and uncertainty at 95% confidence level were certified as 0.918 ± 0.027, 0.662 ± 0.033, and 0.400 ± 0.074 for grades I, II and III, respectively, and the grading was consistent with sensory evaluation. This set of tea CRMs has been certified and issued by the National Technical Committee on Reference Materials as China’s first tea CRM based on the fingerprint classification with quantitative characteristics. This method can be used for grading of Xinyang Maojian tea.