Metal ions binding and colloidal destabilization in the model systems: Implication on the magnesium chloride coagulation mechanism in tofu making
Year: 2025
Type: article
Abstract: MgCl 2 -induced soymilk coagulation mechanism in tofu making was explored from perspectives of Mg 2+ binding and colloidal properties in model systems. Isothermal titration calorimetry of bovine serum albumin (BSA)-small molecule mixtures revealed proteins contributed negligibly to Mg 2+ binding sites, instead, substantial Mg 2+ were bound by soymilk-borne small molecules. The results thus suggested the “protein-Mg 2+ -protein bridge” was hardly formed in tofu making. Zeta potentials for both BSA-small molecule system and defatted soymilk changed in a similar pattern relative to the unbound Mg 2+ concentration, indicating only those small molecules-unbound Mg 2+ effectively neutralized the electronegative charges on protein colloidal particles. Turbidity and particle size results revealed a critical zeta potential (−11 mV) was required to induce marked Mg 2+ -defatted soymilk coagulation. For heated defatted soymilks, a critical minimum protein concentration (8 mg/mL) was needed to observe the significant Mg 2+ -induced coagulation. This study is expected to deepen our understanding of Mg 2+ coagulation mechanism in tofu making. • No protein-Mg 2+ -protein bridge was formed. • Small molecules binding substantial Mg 2+ resulted in lower available Mg 2+ to the colloidal particles. • Marked colloidal destabilization was observed when zeta potential increased to −11 mV. • Mg 2+ added heated defatted soymilks significantly coagulated as protein concentration exceeded 8 mg/mL.
Source: Food Chemistry X
Institution: Jiangnan University
Language: English
Topic: Proteins in Food Systems
Subfield: Food Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $2,330
OpenAlex ID: W4408393012