Analysis of glycosidically bound aroma precursors in tea leaves. 1. Qualitative and quantitative analyses of glycosides with aglycons as aroma compounds.

Twenty-six synthetic glycosides constituting aglycons of the main tea aroma compounds ((Z)-3-hexenol, benzyl alcohol, 2-phenylethanol, methyl salicylate, geraniol, linalool, and four isomers of linalool oxides) were synthesized in our laboratory as authentic compounds. Those compounds were used to carry out a direct qualitative and quantitative determination of the glycosides as aroma precursors in different tea cultivars by capillary gas chromatographic−mass spectrometric (GC−MS) analyses after trifluoroacetyl conversion of the tea glycosidic fractions. Eleven β-d-glucopyranosides, 10 β-primeverosides (6-O-β-d-xylopyranosyl-β-d-glucopyranoside) with aglycons as the above alcohols, and geranyl β-vicianoside (6-O-α-l-arabinopyranosyl-β-d-glucopyranoside) were identified (tentatively identified in the case of methyl salicylate β-primeveroside) in fresh tea leaves and quantified on the basis of calibration curves that had been established by using the synthetic compounds. Primeverosides were more abundant th...