Stoichiometric analysis of 20 amino acids, thermogravimetric parameters and trace elements in five types of tea from Guizhou, China, based on entropy analysis (EA) and factor cluster analysis (FCA)

This study employed a range of indicators, including heat of combustion, combustibility, fat content, amino acid content, ash content, crude fiber content, trace element content, and concentrations of catechins, theanine, and caffeine, to develop comprehensive evaluation systems for assessing the quality of five tea samples: Duyun Maojian tea, Liping fragrant tea, Shuicheng spring tea, Huaxi jasmine tea, and Zunyi black tea. Analytical techniques such as gray pattern recognition (GPR), gray principal component analysis (GPCA), gray factor analysis (GFA), entropy analysis (EA), and factor cluster analysis (FCA) were utilized. Based on the 42variable data, the nutritional value ranked as follows: Shuicheng spring tea > Huaxi jasmine tea > Duyun Maojian tea > Liping fragrant tea > Zunyi black tea. These findings offer significant theoretical and practical insights for the determination and comprehensive evaluation of tea quality indicators, contributing to scientific research on the nutrition, health, and classification aspects of tea.