Physicochemical stability and antibacterial mechanism of theabrownins prepared from tea polyphenols catalyzed by polyphenol oxidase and peroxidase

Xiaoqiang Chen; Tingting Chen; Jiayan Liu; Yan'an Wei; Weilong Zhou

doi:10.1007/s10068-023-01341-x

Physicochemical stability and antibacterial mechanism of theabrownins prepared from tea polyphenols catalyzed by polyphenol oxidase and peroxidase

Food Sci Biotechnol. 2023 May 30;33(1):47-61. doi: 10.1007/s10068-023-01341-x. eCollection 2024 Jan.

Authors

Xiaoqiang Chen¹, Tingting Chen¹, Jiayan Liu¹, Yan'an Wei¹, Weilong Zhou²

Affiliations

¹ Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan, 430068 China.
² National Center for Tea Quality Inspection and Testing, Hangzhou Tea Research Institute, All China Federation of Supply and Marketing Cooperatives, Hangzhou, 310016 China.

Abstract

Tea polyphenols were used as substrates and oxidized successively by polyphenol oxidase and peroxidase to prepare theabrownins (TBs-dE). The conversion rate of catechins to TBs-dE was 90.91%. The ultraviolet and infrared spectroscopic properties and zeta potential of TBs-dE were characterized. TBs-dE is more stable at pH 5.0-7.0, about 25 °C or in dark environment. Ultraviolet light and sunlight can deepen its color due to the further oxidative polymerization. Mg²⁺, Cu²⁺, and Al³⁺ had a significant effect on the stability of TBs-dE. The inhibitory rates of TBs-dE (1 mg/mL) against Staphylococcus aureus and Escherichia coli DH5α were 51.45% and 45.05%, respectively. After TBs-dE treatment, the cell morphology of both bacteria changed, some cell walls were blurred, and the cytoplasmic content leaked. The research results can provide theoretical support for the industrialization of theabrownins.

Keywords: Antibacterial mechanism; Enzymatic oxidation; Physicochemical stability; Theabrownins.

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