Scientists from St Petersburg University propose a simple express method for assessing the amino acid composition of GABA tea

GABA tea is rich in gamma-aminobutyric acid (GABA), which benefits the nervous system, liver, and kidneys. The method developed by the scientists will optimise the production of domestic GABA tea with a high content of GABA and other essential amino acids.

In 1987, Japanese scientists developed a technology for producing GABA tea by placing the leaves of any type of ordinary tea in an oxygen-free environment—an atmosphere of nitrogen or carbon dioxide — for several hours. As a result, the leaves accumulate large amounts of gamma-aminobutyric acid (GABA), which plays a crucial role in the central nervous system of humans and other mammals by acting as an inhibitor of brain cells, preventing over-excitation. Additionally, GABA enhances memory, regulates blood pressure, supports liver and kidney function, and helps prevent diabetic conditions. Thus, GABA tea serves as a source of this valuable compound, along with other amino acids present in tea. 

The findings of the research supported by a grant from the Russian Science Foundation are published in the Journal of Food Composition and Analysis.

For the first time in Russia, a technology for producing GABA tea is being developed using domestic raw materials — the Colchida cultivar, which grows in Krasnodar Krai along the Black Sea coast. To optimise processing conditions, rapid methods for assessing the qualitative and quantitative composition of amino acids are required.

The scientists from St Petersburg University and the Federal Research Centre "Subtropical Scientific Centre of the Russian Academy of Sciences" have analysed the amino acid composition and content in samples of GABA tea made from the Colchida cultivar. The chemists proposed a comprehensive approach with two analytical options.

Chromatographic methods enable the separation of components in complex mixtures based on their differential distribution between mobile and stationary phases. Porous sorbents made of silica gel, aluminium oxide, or polymeric materials serve as stationary phases. Depending on the analytical approach — whether the sorbent is packed in a column or applied as a thin layer on a plate — chromatography is classified as high-performance liquid chromatography (HPLC) or high-performance thin-layer chromatography (HPTLC). For tea product optimisation, it is often unnecessary to quantify all amino acids precisely; rather, an express assessment of their content variations under different conditions is sufficient. High-performance thin-layer chromatography facilitates this rapid analysis, while high-performance liquid chromatography provides precise quantification of specific amino acids in plant samples.

Using this approach, chromatographic profiles of amino acids were obtained from 15 samples of GABA tea derived from the Colchida cultivar, with leaves subjected to oxygen-free conditions for durations ranging from six hours to four days. The analysis revealed that the highest concentration of gamma-aminobutyric acid was present in GABA tea produced from fresh leaves that had not undergone prolonged drying, wilting, or curling and had been kept in oxygen-free conditions for eight hours to four days.

The research was conducted within the framework of the project "Smart materials for creating new approaches to concentration and separation in bioanalysis", supported by a grant from the Russian Science Foundation. St Petersburg University has been among the leading recipients of grants from the Russian Science Foundation in recent years. In 2022 and 2023, St Petersburg University was the leader in the number of grants from the Russian Science Foundation: in 2022, St Petersburg University researchers received 112 grants, which is 5.5% of the total number of winning projects and the largest number of grants for one organisation. In 2023, the University maintained its leadership in this contest of the Russian Science Foundation: scholars from St Petersburg University received 70 grants, which is 5% of the total number of winning projects. Additionally, 41 research projects at St Petersburg University were supported by the Russian Science Foundation at the end of 2024.

Additionally, both chromatographic methods demonstrated the ability to detect amino acids in samples at very low concentrations — starting from 0.01 micrograms per millilitre — while maintaining an estimation accuracy of up to 95%. Since tea typically contains these substances in concentrations hundreds of times higher, the developed methods are well-suited for their precise quantification. Moreover, the method can be applied for the express analysis of amino acids in other, more complex plant samples. To enhance the selective separation of target compounds, smart materials, such as ionic liquids, are incorporated into the mobile or stationary phases.

"Both methods gave comparable results, accurately identifying tea samples with high GABA content. Thus, the developed approach can be used for a fast and technologically simple assessment of the amino acid composition of teas. The results of our study can be used by domestic producers to further improve the technology of GABA-rich tea production," said Professor Liudmila Kartsova, Principal Investigator, Leading Research Associate in the Department of Organic Chemistry at St Petersburg University.

St Petersburg University, the oldest university in Russia, was founded on 28 January (8 February) 1724. This is the day when Peter the Great issued a decree establishing the University and the Russian Academy of Sciences. St Petersburg University today is a major centre for education and research. More than 20,000 students study here, and more than 15 major laboratories and 23 resource centres have been established as part of the country’s leading Research Park. Graduates of the University have been recipients of the Nobel and Fields Prizes on multiple occasions.

Recently, St Petersburg, the Northern Capital of Russia, officially introduced a new holiday — Day of St Petersburg University — which has been included in the St Petersburg Law "On holidays and commemorative days in St Petersburg".

In February 2025, a ceremonial event was held, during which Roscosmos cosmonauts presented the University with the "300^th anniversary of St Petersburg University" flag, which had travelled to the International Space Station and back.