Wang D, Yoshimura T, Kubota K, Kobayashi A
Laboratory of Food Chemistry, Department of Nutrition and Food Science, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo 112, Japan.
J Agric Food Chem. 2000 Nov;48(11):5411-8. doi: 10.1021/jf000443m.
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 beta-D-glucopyranosides, 10 beta-primeverosides (6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside) with aglycons as the above alcohols, and geranyl beta-vicianoside (6-O-alpha-L-arabinopyranosyl-beta-D-glucopyranoside) were identified (tentatively identified in the case of methyl salicylate beta-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 than glucosides in each cultivar we investigated for making green tea, oolong tea, and black tea. Separation of the diastereoisomers of linalool and four isomers of linalool oxides by GC analyses is also discussed.
在我们实验室合成了26种构成主要茶叶香气化合物（(Z)-3-己烯醇、苯甲醇、2-苯乙醇、水杨酸甲酯、香叶醇、芳樟醇以及芳樟醇氧化物的四种异构体）苷元的合成糖苷，作为标准化合物。通过对茶叶糖苷馏分进行三氟乙酰化转化后，利用毛细管气相色谱-质谱联用（GC-MS）分析，使用这些化合物对不同茶树品种中作为香气前体的糖苷进行直接定性和定量测定。在鲜叶中鉴定出11种β-D-葡萄糖苷、10种以上述醇类为苷元的β-樱草糖苷（6-O-β-D-吡喃木糖基-β-D-葡萄糖苷）以及香叶基β-蚕豆糖苷（6-O-α-L-阿拉伯吡喃糖基-β-D-葡萄糖苷）（水杨酸甲酯β-樱草糖苷为暂定鉴定），并根据使用合成化合物建立的校准曲线进行定量。在我们研究的用于制作绿茶、乌龙茶和红茶的每个品种中，樱草糖苷比葡萄糖苷含量更丰富。还讨论了通过GC分析分离芳樟醇的非对映异构体和芳樟醇氧化物的四种异构体。
