Exploring the endogenous and exogenous key aroma-active components in three aroma types of black teas from different...

Historically, the evaluation of tea cultivar suitability has centered on taste-related compounds such as polyphenols and amino acids in fresh shoots. Although aroma plays a critical role in determining tea quality and consumer preference, its assessment has often been overlooked due to the analytical challenges associated with trace volatile compounds. In this study, the characteristic aroma types and flavor profiles of black teas produced from 17 national cultivars were investigated using chemometric analysis and sensory evaluation. Sensory evaluation combined with multivariate statistical analysis revealed three distinct aroma profiles among the samples: endogenous "floral" and "sweet" types, associated with (E)-nerolidol, (E)-farnesene epoxide, and (3E)-5-ethyl-6-methylhept-3-en-2-one; and a processing-derived "high fired" aroma, generated from 15 thermal volatile compounds, including carotenoid derivatives and pyrazines. Absolute quantification of the characteristic components corresponding to the three aroma types, together with odor activity value (OAV) analysis, identified (E)-nerolidol (OAV: 1.53) and octanal (OAV: 11.02) as the key aroma-active compounds in the "floral" and "sweet" sample groups, respectively. In the "high fired" group, six compounds, including (E)-β-ionone (OAV: 5785.71) and 2,6-diethylpyrazine (OAV: 1.74), were identified as key aroma-active components. These compounds represent the most distinctive endogenous and exogenous aroma-active contributors across the respective black tea aroma types, with contributions that varied by cultivar. Among the cultivars studied, 'Jinmudan' and 'Zhongcha 108' exhibited the most typical "floral" and "sweet" aroma profiles, respectively. This systems-level view of the cultivar-process-aroma relationship offers a new perspective for quality control, enabling targeted adjustments in materials and processing to develop distinctive, market-aligned aroma profiles.