Contribution of theanine to the temperature-induced changes in aroma profile of Wuyi rock tea.

Theanine is a distinctive amino acid in tea that plays a vital role in tea flavor during the roasting process. Model thermal reactions of total amino acids and sugars with different roasting conditions (low-fire, middle-fire, and high-fire) showed theanine competitively inhibited the formation of indole, skatole, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, and Strecker aldehydes, while greatly stimulated the production of roasty pyrazines. In addition, highest amounts of pyrazines were obtained under high-fire degree. Quantification of these reaction products in Wuyi rock tea (WRT) was realized in different roasted Dahongpao teas by means of sensomics approach. The quantitative data revealed the biggest influence of roasting temperatures on the formation of reaction products among indole, lipid oxidation products, and pyrazines, while other reaction products were only slightly affected. The findings of this study provide a fresh perspective on the impact of theanine on aroma formation during the roasting process, which will help to explore the formation of key odorants during tea production.