Analysis of free amino acids in Chinese teas and flower of tea plant by high performance liquid chromatography combined with solid-phase extraction

• Published in: Food chemistry Vol. 123; no. 4; pp. 1259 - 1266
• Main Authors: Wang, Lin, Xu, Renjie, Hu, Bing, Li, Wei, Sun, Yi, Tu, Youying, Zeng, Xiaoxiong
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.12.2010; [Amsterdam]: Elsevier Science; Elsevier
• Subjects: Amino acid composition; analytical methods; Biological and medical sciences; black tea; Camellia sinensis; chemical analysis; chemical constituents of plants; Coffee, tea and other stimulative beverage industries; Derivatisation; flowers; food analysis; food composition; Food industries; food processing quality; Free amino acids; Fundamental and applied biological sciences. Psychology; green tea; high performance liquid chromatography; histidine; HPLC-DAD; Solid-phase extraction; Tea; theanine; Tea; Free amino acids; HPLC-DAD; Solid-phase extraction; Derivatisation; Solid phase extraction; Flower; Plant part; Analysis; HPLC chromatography
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2010.05.063

An effective liquid chromatographic method that involved precolumn derivatisation with o-phthaladehyde combined with solid-phase extraction has been developed for the determination of free amino acids in tea. Firstly, tea infusion was treated by C18 cartridge before derivatisation, resulting in great improvement of separation by Zorbax Eclipse XDB-C 18 column. Then, the contents of free amino acids in Chinese green, black, and Oolong teas and the flower of plant Camellia sinensis have been determined. The results showed that theanine was the most abundant amino acid in teas, and green tea contained much higher amounts of free amino acids than fermented ones. While the contents and composition of free amino acids in tea flower were quite different from those of teas. The tea flower contained much higher content of free amino acids. Furthermore, although theanine was the most abundant amino acid in tea flower as tea, histidine became the second one.