Understanding different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea (Camellia sinensis) provides new insights into the safe and effective alteration of tea flavor and function

• Published in: Critical reviews in food science and nutrition 2020-03, Vol.60 (5), p.844-858
• Main Authors: Yu, Zhenming, Yang, Ziyin
• Format: Article
• Language: English
• Subjects: Accumulation; Amino acid; Amino acids; Amino Acids - biosynthesis; Amino Acids - metabolism; Biosynthesis; Camellia sinensis; Camellia sinensis - chemistry; Camellia sinensis - metabolism; Damage accumulation; Flavor; Flavoring Agents - metabolism; Flavors; GABA; Humans; l-theanine; Metabolism; Plant Leaves - chemistry; Plant Leaves - metabolism; Raw materials; regulation; Regulatory mechanisms (biology); stress; Taste; Tea; Tea - chemistry; Tea - metabolism; Theanine; γ-Aminobutyric acid
• ISSN: 1040-8398; 1549-7852
• DOI: 10.1080/10408398.2018.1552245

Amino acids are the main contributors to tea (Camellia sinensis) flavor and function. Tea leaves contain not only proteinaceous amino acids but also specialized non-proteinaceous amino acids such as L-theanine and γ-aminobutyric acid (GABA). Here, we review different regulatory mechanisms of proteinaceous and non-proteinaceous amino acid formation in tea. The key findings were: (1) High accumulations of proteinaceous amino acids mainly result from protein degradation, which occurs in each tea stage, including preharvest, postharvest, manufacturing, and deep processing; (2) L-Theanine is the most represented non-proteinaceous amino acid that contributes to tea taste and function. Its accumulation is influenced more by the variety than by exogenous factors; and (3) GABA is the second most represented non-proteinaceous amino acid that contributes to tea function. Its formation, and resulting accumulation, are responses to stress. The combination of anoxic stress and mechanical damage are essential for a high GABA accumulation. An understanding of the biosynthesis, metabolism, and regulatory mechanisms of the proteinaceous and non-proteinaceous amino acids during the whole process from raw materials to tea products is necessary to safely and effectively alter tea flavor and function.