Changes in Gustatory Substances and Palatability of Matcha (powdered Tencha) during Aging of Tencha (green tea)

研究了抹茶（粉状天茶）在10℃空气和氮气环境中陈化过程中味觉物质和适口性的变化。与新鲜（未陈化）天茶和氮气陈化6个月的天茶相比，空气陈化6个月的天茶的甜味和鲜味更强，涩味和苦味更弱，风味更鲜美。在空气和氮气环境下，抹茶洗脱液中儿茶素含量在陈年过程中略有下降。在6个月的陈化过程中，抹茶液中咖啡因、游离氨基酸（含茶氨酸）和皂苷的含量保持不变。在空气气氛下陈化，游离糖含量略有下降。随着天茶的陈化，抹茶的泡沫体积增大，空气陈化时泡沫体积大于氮气陈化。在两种气氛条件下陈化6个月，抹茶洗脱液粘度和果胶含量均有所增加。天茶陈化对抹茶适口性的改善可能与泡沫体积的增加有关。储藏6个月后，天茶中总维生素C和抗坏血酸在空气和氮中的残留率分别为80%和90%左右。储藏6个月后，天茶叶绿素及其相关衍生物的含量在两种大气条件下变化不大。虽然叶绿素酶在天茶贮藏6个月后仍有足够的活性，但在低水分的贮藏条件下，该酶并未引起天茶中叶绿素的降解。结果表明，天茶在5℃空气中贮存6个月后，保持了满意的品质。儿茶素、咖啡因和果胶对抹茶适口性的影响与茶叶采摘时间无关。

Changes in gustatory substances and palatability of Matcha (powdered Tencha) during aging of Tencha (green tea) in the atmosphere of air or nitrogen at 10℃ were investigated. The Matcha prepared in the Tencha aged for 6 months in the atmosphere of air was feted sweet taste and umami more strongly, astringent and bitter taste more weakly, and flavor more palatably by analytical panels, compared with the Matcha prepared in fresh (unaged) Tencha or Tencha aged under atmosphere of nitrogen for 6 months. The contents of catechins in the eluate of Matcha decreased slightly during aging under both air and nitrogen atmospheres. The contents of caffeine, free amino acids (containing theanine) and saponin in the eluate of Matcha remained constant values during aging for 6 months. The free sugar contents decreased slightly for aging under atmosphere of air. The foaming volume of Matcha increased by aging of Tencha and became greater on the aging under air than under nitrogen. The viscosity of eluate of Matcha and the content of pectin increased during 6 months of aging both atmosphere conditions. The improvement of palatability for Matcha by aging of Tencha may be attributable to the increase of foaming volume.The residual rates of the apparent total vitamin C and ascorbic acid in Tencha were about 80% in air and 90% in nitorgen after 6 months of storage, respectively. The contents of chlorophyll and its related derivatives in Tencha varied very little both atmospheric conditions after 6 months of storage. Though chlorophyllase remained enough activity to react after 6 months-storage of Tencha, the enzyme did not cause the degradation of chlorophyll in Tencha under the storage condition of low moisture. These results indicate that Tencha have maintained satisfactory quality during the 6 months-storage in air at 5℃ for aging to favorable Matcha.Catechins, caffeine and pectin did not contribute to the difference in palatability of Matcha with picking time of tea leaves.