College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China.
Food Res Int. 2022 Dec;162(Pt B):112169. doi: 10.1016/j.foodres.2022.112169. Epub 2022 Nov 18.
Huangjinya is a light-sensitive mutant tea cultivar that produces fresh leaves with a yellow phenotype, and the leaves also be used to produce black tea with special sensory characteristics. To thoroughly explore the chemical changes that occur during the processing of Huangjinya black tea, tea samples were collected from each processing step to perform quantitative and qualitative analyses by high-performance liquid chromatography and ultra-performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS). Compared to fresh tea leaves, only approximately 20% of the catechins remained at the end of processing, while theaflavins levels peaked at the rolling step and were slightly reduced in the fermentation and drying processes. The levels of amino acids derived from protein hydrolysis increased significantly in the withering and rolling processes. Altogether, 620 differential metabolites were identified from 11 subclasses using widely targeted metabolomics based on UPLC-HRMS for the four steps used to process Huangjinya black tea. Flavonoids, phenolic acids, and lipids were the three major classes of differential metabolites, accounting for 52.4% of the differential compounds. The greatest changes in the metabolite profile occurred during the rolling step, with 292 metabolites showing increases or decreases. Two glycoconjugates of the amino acid were first identified in tea, which was sharply increased in the drying stage. The present study provides comprehensive information on the chemical changes during the processing of Huangjinya black tea, and this information is valuable for optimizing manufacturing process and utilization of the Huangjinya tea plant.
黄金芽是一种光敏感突变体茶品种，其鲜叶呈现黄色表型，可用于制作具有特殊感官特征的红茶。为了深入探究黄金芽红茶加工过程中的化学变化，我们在每个加工步骤中收集茶叶样品，通过高效液相色谱法和超高效液相色谱-高分辨质谱联用（UPLC-HRMS）进行定量和定性分析。与鲜茶叶相比，加工结束时儿茶素仅保留了约 20%，茶黄素水平在揉捻步骤达到峰值，在发酵和干燥过程中略有降低。在萎凋和揉捻过程中，来自蛋白质水解的氨基酸水平显著增加。使用基于 UPLC-HRMS 的广泛靶向代谢组学，我们从加工黄金芽红茶的四个步骤中共鉴定出 620 种差异代谢物，分为 11 个亚类。类黄酮、酚酸和脂质是差异代谢物的三个主要类别，占差异化合物的 52.4%。代谢物谱的最大变化发生在揉捻步骤，有 292 种代谢物增加或减少。首次在茶中鉴定出两种氨基酸的糖缀合物，在干燥阶段急剧增加。本研究提供了黄金芽红茶加工过程中化学变化的全面信息，这对于优化制造工艺和利用黄金芽茶树具有重要价值。
