Process optimization and volatile characterization of floral black tea from Ziyang population cultivar

Tumbling timing in withering dually regulates key aroma volatiles. • Floral and green volatiles antagonistically shape aroma quality. • Phenylethyl alcohol dominates the floral aroma of Ziyang population black tea. • Tumbling timing and fermentation time interact to influence aroma quality. Distinct floral aroma is a key sensory attribute of high-quality black tea. Here, response surface methodology (RSM) was applied to systematically optimize the processing technology of floral-flavored black tea from the fresh leaves of Ziyang population tea plant, with the timing of tumbling during withering (expressed as leaf moisture content), rolling time, and fermentation time as independent variables and sensory aroma score as the response value. Volatile compounds in the resulting tea samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The optimal floral quality was achieved when tumbling started at a moisture content of 713.9 g/kg (wet basis) during withering, with 47.19 min rolling and 3.05 h fermentation. Through gas chromatography-olfactometry (GC-O), odor activity value (OAV) calculation, and aroma recombination, five compounds were identified as the key floral aroma contributors: benzeneacetaldehyde, linalool, geraniol, phenylethyl alcohol, and β -damascenone. Enrichment analysis of the key aroma compounds (OAV > 1) during processing revealed that an appropriate tumbling timing (at 700–720 g/kg moisture content, wet basis) synergistically elevated the levels of most key floral volatiles while effectively suppressing the accumulation of grassy volatiles. Moreover, moderate prolongation of rolling (45–55 min) and fermentation (3.0–3.5 h) facilitated the enrichment of specific floral volatiles (phenylethyl alcohol, linalool, and β -damascenone) and significantly reduced the contents of typical grassy volatiles (hexanal and ( Z )-3-hexen-1-ol). Overall, this study offers new insights into the precise regulation and enhancement of floral aroma substances in black tea processing. Download: Download high-res image (297KB) Download: Download full-size image