A novel efficient liquefaction process for corn starch through ternary deep eutectic solvent: Products characterization and liquefaction mechanism

A novel approach for the solvothermal liquefaction of corn starch (CS) was investigated, using ternary deep eutectic solvent (TDES) as both an acidic catalyst and a source of liquefaction reagent. Synergistic effects from multi-component TDES were observed, leading to milder reaction conditions (110 °C, 35 min) and improved product selectivity (relative content of polyhydroxy compounds up to 97.83 %). As a result, a viscosity of 351.76 mPa·s, hydroxyl number of 131.98 mg KOH/g, and acid number of 5.56 mg KOH/g of LP-60 with comparable polyol properties were obtained. Liquefaction residue analysis revealed a significant enhancement in the reactivity of CS by disrupting its recalcitrant structure through electrostatic interactions and hydrogen bonding in TDES, as evidenced by the significant reduction of short-range ordering (R_1047/1022 and R_995/1022) and C1 (C-C/C-H), C3 (C=O/O-C-O) components of the starch granule surface. According to the gas chromatography-mass spectroscopy result, the reaction pathway and mass balance for CS liquefaction in the TDES system were proposed. This study provides an efficient and mild route for starch liquefaction using TDES.