Characteristic Flavor Substances of Guizhou Black Tea and the Environmental Factors Influencing Their Formation Using Stable Isotopes and Headspace Gas Chromatography-Ion Mobility Spectrometry

Guizhou is one of the most important black tea producing areas in China. The purpose of this study was to explore the characteristic flavor compounds of Guizhou black tea and investigate the influence of environmental factors on the formation of black tea flavor components. In this study, HS-GC-IMS was used to identify 143 compounds from black tea samples. OPLS-DA was employed to analyze the data, effectively distinguishing black tea from different origins. A total of 83 significant flavor compounds were selected as potential markers using the VIP variable selection method and OAV screening. Cluster analysis was used to identify the characteristic flavor compounds in black tea samples from different origins. In addition, by investigating the climate environment of various production regions and analyzing the volatile components along with stable C and N isotope ratios of samples, it was discovered that the development of volatile components in black tea could be significantly influenced by ambient temperature and light. In regions with higher temperatures, the concentration of volatile components with floral, fruity, and sweet aromas is higher, resulting in a more intense aroma in black tea. In regions with low ambient temperatures but strong sunlight, black tea contains higher levels of components that give it a fresh and nutty aroma. As a result, the aroma of black tea is relatively elegant and fresh. At the same time, it was found that the stable isotope ratios of C and N in black tea were also significantly affected by ambient temperature and were positively correlated. This study introduces a fresh perspective for the comprehensive examination of Guizhou black tea, offering theoretical guidance for optimizing planting conditions and enhancing product quality. Its positive influence on promoting the development of the Guizhou black tea industry is noteworthy.