Comparison of Volatile and Nonvolatile Metabolites in Black Tea under Four Second-Drying Methods Using Widely Targeted Metabolomics

Abstract

Second-drying has an impact on the development of flavor and aroma in black tea. However, the effect of the shape changes of the tea leaves during second-drying on the quality of black tea has yet to be evaluated. In this study, GC-TOFMS and UPLC-HRMS identified 411 volatile metabolites and 253 nonvolatile metabolites. Additionally, 107 nonvolatile compounds and 21 different volatiles were screened. Significant alterations (p < 0.01) were found in 18 amino acid derivatives, 17 carbohydrates, 20 catechins, 19 flavonoids, 13 phenolic acids, and 4 organic acids. The content of certain amino acids and carbohydrates correlated with the shape of black tea. Furthermore, sweet aroma compound formation was facilitated by hot-air second-drying while the remaining second-drying approaches encouraged the formation of the fruity aroma compound. The results of the study provide a theoretical basis and technical instructions for the accurate and precise processing of premium black tea.

Comparison of Different Grades of Innovative Tanyang Congou Black Tea (Minkehong) Based on Metabolomics and Sensory Evaluation

“…Zhang C et al (2023) found that aged black tea showed a decreasing trend in the pH value in the liquid of tea along with the extension of the year, which might be related to the formation and accumulation of organic acids, such as L-ascorbic acid and salicylic acid [17]. The flavour performance of sweet aroma compounds in black tea may be due to the reduction in carbohydrates and acetylation of AAs during the period of hot-air second-drying [18]. Meanwhile, 620 differential substances were detected through metabolomics techniques during the manufacturing process of "Huangjinya" black tea [19].…”