Sensomics-Assisted Characterization of Key Flowery Aroma Compounds in Lu’an Guapian Green Tea Infusion (Camellia sinensis)

The volatile fraction was isolated from the premium and common grade of Lu'an Guapian green tea infusion by solvent-assisted flavor evaporation distillation. With the application of aroma extract dilution analysis, a total of 52 aroma-active compounds were revealed in the flavor dilution (FD) factor area of 32-8192. Besides, five additional odorants with higher volatility were identified using solid-phase microextraction. The aroma profiles, FD factors, and quantitative data of premium Guapian (PGP) and common Guapian (CGP) showed apparent differences. The intensity of the flowery attribute was significantly higher in PGP than in CGP, while cooked vegetable-like was the most outstanding odor note in CGP. The recombination experiment and the omission test of PGP clarified that dimethyl sulfide, (E,E)-2,4-heptadienal, (E)-β-ionone, (E,Z)-2,6-nonadienal, 2-methylbutanal, indole, 6-methyl-5-hepten-2-one, hexanal, 3-methylbutanal, γ-hexalactone, methyl epijasmonate, linalool, geraniol, and (Z)-3-hexen-1-ol were the key odorants of PGP tea infusion. The omission and addition tests of flowery odorants manifested that (E)-β-ionone, geraniol, and (E,E)-2,4-heptadienal, with higher odor activity values in PGP than in CGP, contributed to the flowery attribute most. The difference in the concentration of the abovementioned odorants with flowery odor notes could be one of the main factors which led to the difference in aroma quality between the two grades of Lu'an Guapian.