Review
Agriculture, Multidisciplinary
Zhen Chen, Zhi Wang, Hongyu Yuan, Ning He
Summary: L-Theanine, the most popular nonprotein amino acid in tea leaves, is widely used in food and pharmaceutical industries for its various health functions. It is now mass-produced in factories through plant extraction, chemical synthesis, or enzymatic transformation. This review comprehensively summarizes information on L-theanine synthesis metabolism and production methods.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
(2021)
Article
Agriculture, Multidisciplinary
Jing Li, Qing-Hui Li, Xu-Yang Zhang, Lu-Yu Zhang, Pei-Ling Zhao, Ting Wen, Jia-Qi Zhang, Wen-Luan Xu, Fei Guo, Hua Zhao, Yu Wang, Pu Wang, De-Jiang Ni, Ming-Le Wang
Summary: Short-term magnesium deficiency partially improves quality constituents of tea leaves, while long-term magnesium deficiency can lead to decreased quality, with increased bitterness, astringency, and decreased umami taste. Global transcriptome changes and differential gene expression are observed in response to magnesium deficiency, affecting biosynthesis of flavonoids, caffeine, theanine, and other secondary metabolisms.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
(2021)
Article
Chemistry, Applied
Bo Zhou, Yiyong Chen, Lanting Zeng, Yingying Cui, Jianlong Li, Hao Tang, Jiayu Liu, Jinchi Tang
Summary: The long-term cultivation of tea plants without fertilization can decrease yield and affect the quality of tea, particularly its color, taste, and aroma. This study provides important information regarding the effects of soil nutrient deficiency on tea quality and the rational fertilization of tea gardens.
Article
Food Science & Technology
Liwen Wang, Margaret Brennan, Shiming Li, Hui Zhao, Klaus W. Lange, Charles Brennan
Summary: This review focuses on the relaxation effect of L-theanine found in tea, discussing animal models, human trials, and potential molecular mechanisms involving neuron stem cells. The review also examines the biological efficacy of dietary L-theanine in relation to gastrointestinal changes and interactions with other food components.
FOOD SCIENCE AND HUMAN WELLNESS
(2022)
Article
Chemistry, Applied
Xiangyang Guo, Chi-Tang Ho, Wilfried Schwab, Xiaochun Wan
Summary: The study showed that fresh tea leaves plucked in summer can be used for green tea production, resulting in a green tea with strong fragrance and nutty odors. It was also found that L-theanine is an important precursor for the formation of green tea aroma.
Article
Food Science & Technology
Yilin Mao, He Li, Yu Wang, Kai Fan, Yujie Song, Xiao Han, Jie Zhang, Shibo Ding, Dapeng Song, Hui Wang, Zhaotang Ding
Summary: A monitoring model of the biochemical components of tea leaves based on hyperspectral imaging technology was established to quantitatively judge the withering and fermentation degrees of fresh tea leaves. The results showed that CARS and PLS methods performed the best in feature band selection and machine learning models.
Article
Plant Sciences
Manman Chang, Jingyu Ma, Ying Sun, Liying Tian, Linlin Liu, Qi Chen, Zhaoliang Zhang, Xiaochun Wan, Jun Sun
Summary: This study reveals that Theanine, an important secondary metabolite in tea, is regulated by light. It was found that light up-regulates the expression of CsGGT2 gene, which affects the accumulation of Theanine. CsGGT2 encodes an enzyme that has both synthesis and degradation functions of Theanine. Therefore, light regulates the degradation of Theanine in tea plants by regulating the expression of CsGGT2 gene.
PLANT CELL AND ENVIRONMENT
(2023)
Article
Forestry
Ziwen Zhou, Na Chang, Yaning Lv, Hong Jiang, Cheng Yao, Xiaochun Wan, Yeyun Li, Xianchen Zhang
Summary: This study investigated the effect of plant growth-promoting rhizobacteria on the synthesis of theanine in tea roots. It was found that Bacillus can increase the availability of potassium in the soil, leading to increased theanine synthesis in tea roots.
Article
Biochemical Research Methods
Yongpeng Li, Tiantian Chen, Wei Wang, Hang Liu, Xin Yan, Kuanyu Wu-Zhang, Wei Qin, Lihui Xie, Yaojie Zhang, Bowen Peng, Xinghao Yao, Chen Wang, Sadaf-Ilyas Kayani, Xueqing Fu, Ling Li, Kexuan Tang
Summary: A simple, rapid, efficient, and cost-effective transient transformation system in Artemisia annua was developed, which was demonstrated to be useful for gene functional studies such as gene subcellular localization, promoter activity, and transcription activation assays, providing a new approach to avoid aberrant phenotypes resulting from gene expression in a heterologous system.
Article
Biochemistry & Molecular Biology
Keiko Unno, Yoshio Muguruma, Koichi Inoue, Tomokazu Konishi, Kyoko Taguchi, Sanae Hasegawa-Ishii, Atsuyoshi Shimada, Yoriyuki Nakamura
Summary: By analyzing changes in metabolites in the hippocampus of stress-loaded mice, it was found that stress sensitivity was higher in SAMP10 mice compared to ddY mice, and theanine played a positive role in regulating metabolism in stress-loaded mice.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Food Science & Technology
Yahui Wang, Chenxue Li, Jiaqi Lin, Yun Sun, Shu Wei, Liangyu Wu
Summary: This study conducted complementary metabolomic and proteomic analyses on solar- and indoor-withered oolong tea leaves to elucidate the mechanisms underlying the formation of flavor determinants during the early stage of oolong tea processing. The analysis identified a total of 978 non-volatile compounds and 152 volatile compounds, with differential accumulation of flavonoids and esters in different tea samples. Pathway enrichment analysis revealed that phenylpropanoid and flavonoid metabolisms, as well as protein processing in the endoplasmic reticulum, were the major pathways distinguishing the tea samples. The joint protein-metabolite analysis showed dynamic and distinct changes in the biochemical network induced by multiple stresses during the withering step, leading to decreases in flavonoids and amino acids. Furthermore, fruity and floral aromas, especially volatile terpenoids and phenylpropanoids/benzenoids, were retained or accumulated in the solar withered leaves, potentially contributing to the characteristic flavor of oolong tea made by indoor withered leaves.
Article
Engineering, Chemical
Chenyuan Wu, Ji Qian, Jinyang Zhang, Jun Wang, Bo Li, Zhenbo Wei
Summary: In this study, a self-developed microwave sensing system equipped with optimized models was used to measure the moisture content of withering tea leaves. The results demonstrated the potential application of microwave technology in the tea processing industry.
JOURNAL OF FOOD ENGINEERING
(2022)
Article
Agriculture, Multidisciplinary
Mengru Li, Chi-Tang Ho, Jing Wang, Yuemeng Hu, Xiaoting Zhai, Liang Zhang, Xiaochun Wan, Xiaogen Yang
Summary: Theanine, a non-proteinogenic amino acid in tea leaves, can be released as volatile compounds at high temperatures. It undergoes deamination and intermediate reactions to form various compounds, including pyrroles and amides. Glucose accelerates the degradation of theanine and promotes additional Maillard reactions. The formation of pyrazines and other volatiles in roasted tea leaves is also influenced by the presence of theanine.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
(2022)
Article
Food Science & Technology
Qi Zhang, Xiao-Li Jia, Mei-Hui Chen, Yu-Hua Wang, Shao-Xiong Lin, Yi-Bin Pan, Peng-Yuan Cheng, Ming-Zhe Li, Ying Zhang, Zheng-Wei Luo, Jiang-Hua Ye, Hai-Bin Wang
Summary: The degree of withering significantly affects tea quality. Light withering increases the content of quinones, phenolic acids, lignans, coumarins, and flavonoids. Moderate withering increases the content of terpenoids, organic acids, and lipids.
LWT-FOOD SCIENCE AND TECHNOLOGY
(2023)
Article
Food Science & Technology
Dahe Qiao, Junyan Zhu, Xiaozeng Mi, Hui Xie, Mingtao Shu, Minyi Chen, Rui Li, Shengrui Liu, Chaoling Wei
Summary: The withering time of Taiping Houkui tea (TPHK) leaves is crucial for the stability of its flavor quality, yet its effect and mechanism on flavor formation remains unclear. Through the integration of metabolomics and transcriptomics, this study comprehensively investigated changes in flavor compounds and related gene expression under different withering times. Results showed that withering had the greatest impact on amino acid and aroma volatile content. Most volatiles reached their highest relative content at 6-8 hours of withering time, consistent with sensory evaluation of aroma quality. Plant hormone signal pathways, particularly ABA and JA signals, played a key role in flavor compound variation under different withering times. WGCNA analysis revealed significant associations between ABA, JA, IAA, SA, different flavor substances, and specific modules. JA may be involved in the metabolism of theanine during withering, while ABA may contribute to the accumulation of aromatic amino acids and main aroma components of TPHK. This research can provide valuable insights for optimizing TPHK processing technology.
LWT-FOOD SCIENCE AND TECHNOLOGY
(2023)