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Source and Route of Pyrrolizidine Alkaloid Contamination in Tea Samples

Source and Route of Pyrrolizidine Alkaloid Contamination in Tea Samples

Published on: September 28, 2022

Theabrownins in dark tea form complexes with tea polysaccharide conjugates.

Xiaoqiang Chen^1,2, Mengdie Wang¹, Zhiyuan Wang¹

¹Cooperative Innovation Center of Industrial Fermentation (Ministry of Education and Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Hubei University of Technology, Wuhan, China.

Journal of the Science of Food and Agriculture

|March 6, 2024

Summary

Theabrownins (TBs) in dark tea are complexed with tea polysaccharides, not free. This finding provides a basis for the industrial production of these important quality components.

Keywords:

complex physicochemical properties tea polysaccharide conjugates theabrownins

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Area of Science:

Food Chemistry
Phytochemistry
Analytical Chemistry

Background:

Theabrownins (TBs) are key quality components in dark tea, yet their industrial production remains unachieved.
This study focuses on isolating and characterizing TBs from Pu-erh ripe tea.

Purpose of the Study:

To isolate Theabrownins (TBs) from dark tea using solvent extraction and chromatography.
To characterize the isolated TBs and determine their state within the tea matrix.

Main Methods:

Aqueous extract of Pu-erh ripe tea was processed to remove impurities like caffeine and catechins.
Column chromatography using HPD-750 macroporous resin separated the extract into four fractions (TBs-FC1 to TBs-FC4).
Fractions were analyzed for molecular weight, composition (polysaccharides, absence of small molecules), and spectral properties (UV-visible, IR), and zeta potential.

Main Results:

Four fractions (TBs-FC1-4) were isolated, containing polysaccharides with average molecular weights ranging from 23.380 to 123.000 kDa.
These fractions were identified as complexes of Theabrownins (TBs) and tea polysaccharide conjugates (TPCs).
Spectroscopic analysis confirmed the presence of TBs and TPCs, with zeta potentials indicating stability in aqueous solutions across a pH range.

Conclusions:

Theabrownins (TBs) exist in a combined state with tea polysaccharides, not in a free state, within dark tea.
This discovery offers a theoretical foundation for the industrial-scale production of Theabrownins (TBs).