Unno Keiko, Ikka Takashi, Yamashita Hiroto, Kameoka Yoko, Nakamura Yoriyuki
Tea Science Center, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.
Foods. 2025 Jan 2;14(1):103. doi: 10.3390/foods14010103.
The major components of tea leaves and their infusions were analyzed for various types of green tea available in Japan in 2022. Almost all the green teas used were from the first crop, known for their high amino acid content. The amino acids theanine and arginine in green tea have been shown to reduce stress. On the other hand, epigallocatechin gallate (EGCG) and caffeine, the major components of green tea, counteract the effects of theanine and arginine. We have shown that the CE/TA ratio, which is the ratio of the molar sum of caffeine (C) and EGCG (E) to the molar sum of theanine (T) and arginine (A), can be used to evaluate the stress-relieving effects of each green tea. Green tea with a CE/TA ratio smaller than 3 can be expected to have a stress-reducing effect. The CE/TA ratios of the tea leaves and infusions of Gyokuro, Sencha, and Tamaryokucha were less than 3, indicating that these teas are expected to have stress-relieving effects. In addition, when the same tea leaves were infused repeatedly, it was found that most of the amino acids were eluted by the first and second cups; therefore, no stress-relieving effect could be expected after the third cup.
对2022年日本市面上各种绿茶的茶叶及其冲泡液的主要成分进行了分析。几乎所有使用的绿茶都来自头茬作物，以其高氨基酸含量而闻名。绿茶中的氨基酸茶氨酸和精氨酸已被证明可以减轻压力。另一方面，绿茶的主要成分表没食子儿茶素没食子酸酯（EGCG）和咖啡因会抵消茶氨酸和精氨酸的作用。我们已经表明，咖啡因（C）和EGCG（E）的摩尔总和与茶氨酸（T）和精氨酸（A）的摩尔总和之比即CE/TA比，可用于评估每种绿茶的减压效果。CE/TA比小于3的绿茶有望具有减压效果。玉露、煎茶和玉绿的茶叶及其冲泡液的CE/TA比均小于3，表明这些茶有望具有减压效果。此外，当对同一批茶叶进行多次冲泡时，发现大部分氨基酸在第一杯和第二杯时就被洗脱出来了；因此，第三杯之后就无法期待有减压效果了。
