Decoding the key odorants responsible for the empty cup aroma of Wuyi rock tea 'Dahongpao' and their perception interactions with caffeine

As a famous <italic>Wuyi</italic> rock tea, the empty cup aroma in 'Dahongpao' is distinct compared to the flavor of the tea infusion, but the specific odorants responsible for its unique empty aroma remain unknown. Therefore, the aroma differences between the empty cup and the infusion of 'Dahongpao' were determined via gas chromatography-olfactometry-mass spectrometry (GC-O/MS) and sensory evaluation. The results showed that 39 and 37 odorants were identified in the empty cup and the infusion of 'Dahongpao', respectively. Among them, four compounds with aroma intensities &gt; 2 including <italic>δ</italic>-decalactone, 6-methyl-5-hepten-2-one, (<italic>E</italic>,<italic>E</italic>)-2,4-heptadienal, and methyl phenylacetate were responsible for coconut-like, sweet, flowery, and fruity notes in the empty cup and the infusion. Furthermore, determining their odor thresholds showed that adding caffeine to water significantly reduced these thresholds from 8.08 μg/L, 56.42 μg/L, 29.55 μg/L, and 12.12 μg/L to 6.52 μg/L, 34.12 μg/L, 14.61 μg/L, and 9.05 μg/L, respectively. In conclusion, this study provides valuable insights into the empty-cup aroma of 'Dahongpao' tea beverages and clarifies the role of caffeine in enhancing their pleasant aromatic profile.