Effect and Mechanisms of Magnesium Ion on the Stability of Green Tea Nano-Aggregates

doi:10.7506/spkx1002-6630-20260128-249

Abstract

Abstract: This study aimed to elucidate the mechanisms by which Mg2+ affects the stability of nano-aggregates in green tea infusions and the formation of tea cream. Dynamic light scattering (DLS), laser Doppler velocimetry (LDV) and transmission electron microscopy (TEM) were used to analyze the effect of Mg2+ on the colloidal chemical properties and morphological characteristics of the nano-aggregates. The nano-aggregates were separated by ultrafiltration with different pore sizes, and the retention rates of major chemical components were determined by high performance liquid chromatography (HPLC) and ultraviolet-visible (UV-Vis) spectroscopy. Furthermore, a simple simulation system for green tea nano-aggregates was constructed using bovine serum albumin (BSA) and four catechin monomers. Fluorescence spectroscopy and circular dichroism (CD) spectroscopy were adopted to investigate the effect of Mg2+ on the secondary structure of BSA and its interaction with catechins. Our results demonstrated that Mg2+ neutralized the negative surface charges of nano-aggregates, reducing their electrostatic stability (indicated by a 78% decrease in the absolute zeta potential value). This promoted the further aggregation of tea polyphenols (particularly gallated catechins), caffeine, proteins, and soluble carbohydrates, leading to a near-doubling of the diameter of nano-aggregates and a decrease in their dispersibility. In the simulation system, Mg2+ exerted a temperature-dependent dual effect on BSA-gallated catechin interactions. At 298 K, Mg2+ induced a slight unfolding of BSA structure, creating a conformation that facilitated catechin binding. Conversely, at 310 K, Mg2+ enhanced the structural rigidity of BSA, thereby hindering its interaction with gallated catechins. This study systematically analyzed the effect of Mg2+ on the stability of green tea nano-aggregates from the perspectives of chemical composition, colloidal chemical properties, and catechin-protein interactions, providing theoretical support and a scientific basis for the prevention of tea cream in tea beverages.

Key words: green tea; tea cream; nano-aggregates; magnesium ion; interaction

CLC Number:

TS272

CHEN Yu, YAN Yipeng, HUANG Jieya, GU Xianxian, ZHU Ting, CHEN Zhongzheng, ZHANG Yuanyuan, LIN Xiaorong. Effect and Mechanisms of Magnesium Ion on the Stability of Green Tea Nano-Aggregates[J]. FOOD SCIENCE, 2026, 47(17): 50-59 https://doi.org/10.7506/spkx1002-6630-20260128-249

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Effect and Mechanisms of Magnesium Ion on the Stability of Green Tea Nano-Aggregates

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