Abstract
Kabusecha made from tea leaves grown in the shade is one of the best quality green tea. It has a characteristic refreshing greenish aroma, called “ooika.”
The essential oils from kabusecha and sencha (typical Japanese green tea made from tea leaves grown in an open field) and their fresh leaves were analyzed by GC-MS and the aroma compositions were compared to find the contributory factors to “ooika”.
Remarkable differences were found between the essential oils from kabusecha and sencha, while no significant differences were observed in their fresh leaves. Kabusecha contained large quantities of the ionone series compounds, such as α-ionone, β-ionone, 2, 6, 6-trimethy1-2-hydroxycyclohexan-1-one and 4-(2, 6, 6-trimethyl-1, 2-epoxycyclohexyl)-3-buten-2-one. The latter two compounds were newly identified from green tea.
Carotenoids in kabusecha and sencha and their fresh leaves were determined by spectrophotometric analysis. Fresh leaves of kabusecha contained 1.5 times more carotenoids than fresh leaves of sencha.
In conclusion, the ionone series aroma compounds formed from carotenoids during the green tea manufacturing process and contribute to the “ooika” of kabusecha.
