Effects of fermentation time and shooting period on amino acid derivatives and free amino acid profiles of tea


Salman S., YILMAZ C., GÖKMEN V., ÖZDEMİR F.

LWT-FOOD SCIENCE AND TECHNOLOGY, vol.137, 2021 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 137
  • Publication Date: 2021
  • Doi Number: 10.1016/j.lwt.2020.110481
  • Journal Name: LWT-FOOD SCIENCE AND TECHNOLOGY
  • Journal Indexes: Science Citation Index Expanded, Scopus, Academic Search Premier, PASCAL, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, Biotechnology Research Abstracts, CAB Abstracts, Chemical Abstracts Core, Food Science & Technology Abstracts, Veterinary Science Database
  • Keywords: Oolong tea, Fermentation, Shooting period, Amino acids, Amino acid derivatives, PU-ERH TEAS, GAMMA-AMINOBUTYRIC-ACID, BLACK, OOLONG, GREEN, GABA, PLANTS, WHITE

Abstract

This study aimed to investigate the effect of oxidation on free amino acids and their derivatives in tea. Oolong tea samples, oxidized for 0, 10, 30, and 60 min, green tea, and black tea were produced from the same batch of fresh tea leaves. Effects of shooting periods on free amino acids and their derivatives were also evaluated in this study. Free amino acids and their derivatives were extracted with water and analyzed by LC-MS/MS. It was observed that total amino acid content of teas in the first shooting period (16231 +/- 241 mu g/g-31391 +/- 2034 mu g/g) was higher than the second (9635 +/- 379 mu g/g-11665 +/- 426 mu g/g) and third (13937 +/- 360 mu g/g-17661 +/- 1359 mu g/g) shooting periods. Content of most amino acids including gamma aminobutyric acid (GABA) in black and oolong teas were higher than those of green tea. However, theanine contents of black and oolong teas were lower than that of green tea. Kynurenine, kynurenic acid, quinolinic acid, dopamine, tyramine, phenylethylamine and tryptamine were found in all tea samples. Kynurenic acid content was the highest (1 + 0.1 mu g/g-3+0.4 mu g/g) in green, oolong and black tea samples. Concentrations of kynurenine, kynurenic acid, quinolinic acid, and dopamine were mostly found to be higher in green tea than black tea.