Changes in Key Odorants in Fresh Tea Leaves with Maturity

Abstract

Odorants in aroma extracts isolated from fresh tea leaves change as tea leaves grow. Elucidation of these changes with tea leaf maturity is essential for the cultivation, manufacturing, and quality control. Aroma volatiles were extracted from fresh tea leaf samples using the solvent-assisted flavor evaporation technique (10^-3 Pa). An aroma extract dilution analysis applied to the volatile fractions revealed hexanal, (Z)-3-hexenal, (Z)-1,5-octadien-3-one, (Z)-3-hexenol, 2-isopropyl-3-methoxypyrazine and 2-isobutyl-3-methoxypyrazine were detected with high flavor dilution (FD) factors. These 6 compounds increased with tea leaf maturity, as confirmed by the gas chromatography – mass spectrometry. On the other hand, two other odorants, coumarin and vanillin, were detected with low FD factors and decreased with leaf maturity. This result would be a good contribution to the improvement of cultivation and manufacturing technology, as well as quality control of tea.