Microwave-assisted synthesis of a citric acid–aspartic acid Maillard byproduct solvent: characterization, phytotoxicity assessment, and application in polysaccharide extraction

Abstract

Green solvents are developed as alternatives to hazardous chemical-based systems for biomolecule extraction. In this study, the microwave-assisted synthesis of a citric acid–aspartic acid Maillard byproduct solvent (CAAA-MBS) is reported. Evidence for Maillard chemistry was confirmed by functional group changes, detection of intermediates and advanced Maillard products, pH reduction, and browning index analysis. The CAAA-MBS is characterized by high viscosity (11 665 Pa s), a density of 1.44 ± 0.01 g mL⁻¹, complete miscibility in water but partial solubility in selected organic solvents, and a dissociation temperature of 119.0 ± 5.4 °C. Phytotoxicity assessment using wheat seed germination showed low toxicity at ≤1% (w/v). Notably, the CAAA-MBS showed potential in the extraction of Callisia repens polysaccharides (∼14% yield, dry basis). In conclusion, this is the first study investigating Maillard chemistry in green solvent development and its application in polysaccharide extraction. While the complex nature of Maillard chemistry presents challenges for reproducibility, this study provides new insights into reaction-derived solvent design.