New browning reaction of tea polyphenols during the roasting process of green tea leaves

绿茶叶烘焙过程中茶多酚的新褐变反应

• 批准号: 22700734
• 负责人: MATSUO Yosuke
• 金额: $ 2.66万
• 依托单位: Nagasaki University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Young Scientists (B)
• 财政年份: 2010
• 资助国家: 日本
• 起止时间: 2010 至 2011
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22700734/
• 关键词: ポリフェノール; 褐変反応; アミノ・カルボニル反応; アクリルアミド; 食品; ほうじ茶

Green tea is produced from the leaves of Camellia sinensis. Some green tea products are further roasted to add a characteristic flavor. By roasting, color of the tea leaves changes from green to reddish brown, and the amount of catechins, amino acids, and free sugars decreased. However, details of the chemical reactions of catechins on roasting still are not clarified. In this study, we demonstrated that epigallocatechin-3-O-gallate reacted with theanine and glucose to afford condensation products. Epigallocatechin-3-O-gallate was heated at 150℃in the presence of theanine to yield six new compounds. Two products are red pigments having p-quinone structure, and the production of these pigments may explain the color change of tea leaves by roast treatment. On the other hand, heating of mixtures of epigallocatechin-3-O-gallate, theanine, and glucose at 150℃afforded two products. These products are considered to be produced by condensation of 1-ethyl-5-hydroxy-2-pyrrolidinone, which is produced by Strecker degradation of theanine, with epigallocatechin-3-O-gallate at the A-ring 8 and 6 positions.

绿茶是由茶树的叶子制成的，一些绿茶产品经过烘焙，进一步增加了特有的风味。通过烘焙，茶叶的颜色从绿色变为红棕色，儿茶素、氨基酸和游离氨基酸的含量也增加。然而，儿茶素在烘焙过程中的化学反应细节仍不清楚。在这项研究中，我们证明了表没食子儿茶素-3-O-没食子酸酯与茶氨酸和葡萄糖发生反应。表没食子儿茶素-3-O-没食子酸酯在茶氨酸存在下于150℃加热生成6种新化合物，它们是具有对醌结构的红色色素，这些色素的产生可以解释茶叶的颜色变化。另一方面，将表没食子儿茶素-3-O-没食子酸酯、茶氨酸和葡萄糖的混合物在150℃下加热可得到两种产物。由 1-乙基-5-羟基-2-吡咯烷酮（通过 Strecker 降解茶氨酸产生）与表没食子儿茶素-3-O-没食子酸酯在 A 环 8 和 6 位缩合而产生。

项目成果

茶葉の焙煎加工におけるエピガロカテキンガレートとグルコースとの縮合反応

表没食子儿茶素没食子酸酯与葡萄糖在茶叶烘焙过程中的缩合反应

• 发表时间: 2010
• 作者: 國平雄士;松尾洋介;田中隆;河野功
• 通讯作者: 河野功

Condensation reaction of epigallocatechin-3-O-gallate with theanine during the roasting process of green tea leaves

绿茶叶烘焙过程中表没食子儿茶素-3-O-没食子酸酯与茶氨酸的缩合反应

• 发表时间: 2010
• 作者: Yuji Kunihira;Yosuke Matsuo;Takashi Tanaka;Isao Kouno
• 通讯作者: Isao Kouno

エピガロカテキンガレートによるアクリルアミド生成抑制機構

表没食子儿茶素没食子酸酯抑制丙烯酰胺产生的机制

• 发表时间: 2011
• 作者: 國平雄士;松尾洋介;田中隆;河野功
• 通讯作者: 河野功