Study on the method and mechanism of As and Cd removal from brown rice flour using a deep eutectic solvent-soyasaponin system

Contamination of foodstuffs with harmful substances poses a significant food safety challenge. Deep eutectic solvents (DESs), being biodegradable and environmentally friendly, hold considerable potential for removing such contaminants from grain. In this study, water was introduced as a third component to form novel ternary deep eutectic water-based solvents (DEWSs). These were combined with soyasaponin to enhance the system's surfactant properties and improve removal efficiency. The research primarily investigated the removal efficacy, optimal conditions, and mechanisms of 12 DEWSs for the removal of harmful elements in grain. Experimental results indicate that the presence of water and specific concentrations of soyasaponin significantly enhanced the removal efficiency of three DESs (choline chloride + urea (DEU), choline chloride + citric acid (DEC), and choline chloride + xylitol (DEXY)) for harmful elements. Among these, DEWXY 3 (DEXY:H₂O = 1:1) and DEWC 2 (DEC:H₂O = 7:3) demonstrated optimal removal efficiencies for arsenic and cadmium, respectively, achieving 71.59% and 97.51%. Both the molecular interactions between DEWSs and As/Cd and the interfacial modulation provided by soyasaponin acted synergistically to promote the removal of As and Cd. This system significantly enhanced the removal of As and Cd while preserving the primary composition and structural integrity of brown rice flour, providing novel insights and technical references for food safety remediation.