Flavor and chiral stability of lemon-flavored hard tea during storage

- Aroma stability of lemon-flavored hard tea is storage temperature and time dependent.
- Terpenoid degradation during storage is largely responsible for aroma loss.
- Both linalool degradation and racemization cause the loss of flavor in iced tea.

Flavor stability of hard tea beverage was investigated over eight weeks of storage. The volatile compounds were analyzed using solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and two-dimensional GC-MS. Quantitative analysis showed that the concentrations of linalool, citronellol, geranial, neral, geraniol, and nerol decreased dramatically during storage, whereas α-terpineol showed an increasing trend during storage. Heart-cut two-dimensional GC-MS (2D-GC-MS) chirality analysis showed that (R)-(+)-limonene, (R)-(−)-linalool, (S)-(−)-α-terpineol and (S)-(−)-4-terpineol dominated in the fresh hard tea samples, however, the configuration changed during storage for the terpene alcohols. The storage conditions did not change the configuration of limonene. A conversion of (R)-(−)-linalool to (S)-(+) form was observed during storage. Both (S)-α-terpineol and (S)-4-terpineol dominated at beginning of the storage, but (R)-(+)-α-terpineol became dominated after storage, suggested in addition to isomerization from (S)-α-terpineol, other precursors could also generate α-terpineol with (R)-isomer preference.