2018 ASHS Annual Conference

Tea (Camellia sinensis (L.) Kuntze) offers great benefit to human health and it is the second most popular drink, only eclipsed by water. Oolong tea is popular to consumers because of its unique flavor. The formation of Oolong tea flavor derived from its special processing, especially the shaking procedure that induced the flavor of Oolong tea by mechanical force. We applied the same Tieguanyin withered leaves as material, provided continuous vibrating stimulus to tea leaves as treatment with natural spreading as control, and collected samples continuously during the vibrating. Catechin composition and content were analyzed by LC-MS and the content of volatiles by GC-MS. The results indicated that catechin composition in the vibrating tea leaves were lower than natural spreading. There were significant differences among vibrating time. For volatiles, the relative percentage of alcohols, aldehydes and esters was at 14.75%, 5.29%, and 4.34% respectively, higher than that of the control after 5min vibrating. The ketone was higher in the period of 30~90min, up to 20.41%. The hydrocarbon was up to the peak of 12.95% at 120 min. The phenylacetone was higher in 30~90min with the highest of 20.20%. Linalool and salicylate were higher after 5min, up to 1.82% and 2.22%. Both nerolidol and indole were higher at 120min, up to 1.06% and 2.81%. With decreasing of catechin content by vibrating stimulus, the bitterness of tea soup reduced and the Oolong tea had a much smooth and pleasant taste. Vibrating stimulus increased volatiles at the important stages, which provided basic material for the flavor formation of Oolong tea and eventually resulted the unique quality of Oolong tea.