Coumarin is a natural product well-known for its pleasant sweet-herbaceous and cherry flower-like odor. Despite coumarin is widely found in the plant kingdom, its occurrence in tea leaves is very poorly characterized. In this work, the cultivars, "Shizu-7132", "Koushun" and "Tsuyuhikari" were found to have sweet-herbaceous odor from the 11 Japanese green teas by the sensory descriptive analysis. Application of the stable isotope dilution assay for the quantification of coumarin revealed that the levels of coumarin in these Japanese green tea products with sweet-herbaceous and cherry flower-like odor ranged from 0.26 to 0.88 µg/g of green tea product, whereas the concentrations were generally below 0.2 µg/g of common green tea products. The "Shizu-7132" was found as naturally coumarin-rich green tea. The natural level of
Many modern floricultural varieties have lost their scent during traditional breeding programs. The factors that result in the nonscent emission of some cut flowers remain unclear. The objective of this study was to investigate whether the nonscent emission is due to one of the factors, the lack of suitable substrates (or precursors of scent compounds). Using solid-phase microextraction and dynamic headspace volatile sampling techniques, the supplement of nonvolatile compounds such as 2-coumaric acid glucoside to the unscented cut flower such as Delphinium elatum L. "Blue Bird" enhanced the emission of scent from the flower, which was sufficient for detection by the human olfaction. Interestingly, compared with feeding with each compound, the combination of sodium acetate and 2-coumaric acid glucoside showed the synergy effect on enhancement of coumarin, a cherry leaf-like scent emission from the flower, which is due to one of factors that sodium acetate enhanced the activity of beta-glucosidase being involved in the formation of the scent compound. These results suggest that some enzymes responsible for the formation of floral scents indeed occur in the unscented flowers such as Delphinium elatum L. "Blue Bird", and the non- or low-scent emission of the flowers are due to the lack of suitable substrates.
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