Abstract:

Based on the content and dissolution rate of flavonoids, aroma and color, this study investigated the optimization
of processing and brewing conditions for lotus leaf tea. Lotus leaf tea was stored for 0, 6, and 12 months, and their
aroma components were extracted by solid-phase micro-extraction (SPME) and analyzed by gass chromatography-mass
spectrometry (GC-MS). Color changes of lotus leaf tea were also measured using a color difference meter. The highest
content of flavonoids was found in the full-bloom lotus leaves. The optimized conditions for processing lotus leaf tea were
determined as fixation by microwave irradiation at 640 W for 90 s and drying at 70 ℃; and the optimized brewing conditions
were 100 ℃ for 15 min. A total of 102 aroma components were identified in lotus leaf tea after three storage periods. As
the storage time prolonged, the number of main aroma components decreased, but their relative contents increased. Benzyl
alcohol was the main aroma component in lotus leaf tea stored for 6 and 12 months. Moreover, isoamylol responsible
for the unpleasant odor was generated during storage. During the first 6 months of storage, the L* and b* values of lotus
leaf tea remarkably decreased, as the color became dimmer and was changed to blue, and the L* and b* values increased
slightly at the last stage of storage. While the a* value increased continuously in the whole storage period, the greenness
decreased continuously.

Key words: lotus leaf tea, flavonoid, processing and storage, GC-MS, aroma, color