Formation Mechanism of Tea Aroma and Search for Precursor

从茶叶热水浸出物中分离得到糖苷组分丁醇浸出物，再进行乙酰化反应，分离出各组分。通过硅胶柱层析，得到BA-6和BA-7两个组分，经光谱分析鉴定为(Z)-3-己烯基-β-D-吡喃葡萄糖苷四乙酸酯。后者与人工合成的苄基-β-D-葡萄糖苷四乙酸酯在物理和光谱方面都是一致的。绿茶用新鲜茶叶制备的丙酮粉和商品β-D-葡萄糖苷酶酶解绿茶中也得到了粗苷。此外，还采用了非酶盐酸水解法。不同酶解后得到的挥发性化合物基本相同，但经β-D-葡萄糖苷酶酶解后得到大量的苯甲醇和(Z)-3-己烯醇。这一结果与这些挥发物中的β-D-葡萄糖苷作为香气前体在新鲜茶叶中的存在是一致的。

From the hot water extract of tea leaves, glycoside fraction was obtained as butanol extract, which was acetylated to separate each compounds. Through silica gel column, two fractions, BA-6 and BA-7, were shown to be single compound on the thin layer chromatogram.The former was identified with (Z)-3-hexenyl-beta-D-glucopyranoside tetraacete based on the spectrometric analyses. The latter was identical with synthetic benzyl-beta-D-glucopyranoside tetraacetate in all physical and spectrometric aspects.The crude glycoside fraction was also isolated from green tea which was enzymatically hydrolyzed with acetone powder prepared from fresh tea leaves and commercial beta-D-glucosidase. Non-enzymatic hydrolysis with hydrochloric acid was also applied. The volatile compounds formed after different hydrolysis were almost same, however, large amounts of benzyl alcohol and (Z)-3-hexenol were obtained after the hydrolysis with beta-D-glucosidase. This result is consistent with the presence of beta-D-glucosides of these volatiles in fresh tea leaves as aroma precursor.