Analysis Of Quality Characteristics Of Guizhou Black Tea Based On UPLC-Q-Orbitrap High-resolution Mass Spectrometry And ICP-MS

Objective:Using the non-targeted detection and analysis technology with simple pretreatment,high accuracy,and comprehensive analysis of non-volatile components of tea,combined with ICP-MS to detect and analyze the content of mineral elements in tea,comprehensively evaluate the quality characteristics of Guizhou black tea.Methods:UPLC-Q-Orbitrap high-resolution mass spectrometry technology was used to comprehensively detect and analyze non-volatile substances in Guizhou black tea and high-quality black tea from other provinces.Multivariate statistical methods such as PCA were used to screen differential compounds,and databases such as chemspider and mzcloud were used to identify differential compounds.At the same time,ICP-MS was used to detect and analyze the content of mineral elements in Guizhou black tea and high-quality black tea from other provinces,and comprehensively evaluates the quality characteristics of different varieties and grades of tea.Results:The results of non-targeted metabolomics test showed that flavonoids,amino acids and their derivatives are the most contained compounds in Guizhou black tea,and the three types of Guizhou black tea have obvious differences in composition.A total of 23 differential compounds were identified in the three types of Guizhou black tea.The main ones were catechins,flavonoids and organic acids,and the main metabolic pathway affected by the differential compounds was the metabolism of flavonoids.Through detecting and analyzing,it was found that there were obvious differences between the three kinds of black tea from Guizhou and other provinces,and many different compounds were obtained.22,11,and 13 grade-related compounds have been screened and identified in Pu’an black tea,Shiqian moss tea and Zunyi black tea of different grades.The types of different compounds mainly involve amino acids and their derivatives,alkaloids and flavonoids,etc.The results of ICP-MS analysis showed that there were differences in the content of 12 elements in the three types of Guizhou black tea,namely Mg,P,K,Ca,Mn,Co,Ni,Cu,Zn,Se,Sr,Mo;The difference elements between Guizhou black tea with black tea from other provinces,mainly involve elements such as Na,K,Fe,Se,Ni,Mo,Sr and Co;The contents of P,Na,Zn,Fe,Cu,Sr and Ca in different grades of Pu’an black tea are different;The contents of Ca,Mn,Sr,K,Mg,Co,Na,Fe,Cu,Zn and Mo in Shiqian moss tea of different grades are different;There are differences in the contents of K,Zn and Sr among different grades of Zunyi black tea;Conclusions:The main differential compounds among Guizhou black tea were caffeic acid,neochlorogenic acid,4,5-dicaffeoylquinic acid,quercetin,quercitrin,rutin,luteolin,maesopsin,7-methylxanthine.In different grades of Guizhou black tea,there is a rule that the content of amino acids and their derivatives,alkaloids,organic acids are high in high grades,and the content of flavonoids such as genistein and quercetin-3β-D-glucoside are high in low grades.Among the three types of black tea in Guizhou,Mg,K,Mn,Co,Ni,Zn,and Se are the main differential elements,and the differential elements related to grade are Zn,K,Ca,and Sr.Compared with black tea from other provinces,Guizhou black tea has higher contents of naringin,1-Aminocyclohexanecarboxylic acid,N-acetyl-DL-tryptophan,Ni,Mo and Co.These quality difference indicators can provide a reference for the research on the material basis of the quality evaluation of Guizhou black tea.