基于UPLC-MS/MS技术的9个白茶实物标准样主要化学成分分析OA北大核心CSTPCD

To evaluate white tea products of different types and grades objectively and systematically,ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS)technology was used to detect and analyze main chemical compounds such as catechins and theanine in white tea standard samples of different types and different grades of the same type,using Chinese white tea standard samples as the test material.The results showed that,with the decrease of grade,the overall"fragrance and flavor"gradually weaken,and the taste changes from clean and umami to clean and sweet,and then to mellow and thick.Compared with different grades of white tea,it was found that there was a significant positive correlation between the grades of white tea and arginine(Arg),aspartic acid(Asp),threonine(Thr).Among them,Asp decreased with the decrease of grade,so Asp was the key main chemical compounds that determined the taste differences of different grades of Baihao Yinzhen,Baimudan,Gongmei and Shoumei.Partial least squares-discriminant analysis(PLS-DA)of main chemical compounds in samples of different types revealed that the variable importance projection(VIP)values of 12 compounds including alanine(Ala),theanine(L-Thea),histidine(His),lysine(Lys),as well as epicatechin gallate(ECG)and epigallocatechin gallate(EGCG),were greater than or equal to 1.0.Analysis of main chemical compounds in samples of the same type with different grades revealed that characteristic main chemical compounds exhibited were proline(Pro),His,L-Thea and phenylalanine(Phe).Above results provided theoretical reference for the evaluation and analysis of the flavor quality of white tea products in China,and had reference value for the quality level discrimination of white tea products with different types and different grades of the same type.