Highly efficient esterification of waxy maize starch in choline chloride/acetic acid acidic deep eutectic solvent...

Area of Science:

• Green Chemistry
• Biopolymer Modification
• Materials Science

Background:

• Solvent selection is crucial for efficient chemical modification of starch.
• Traditional methods may involve harsh chemicals or enzymes, posing environmental concerns.

Purpose of the Study:

• To develop an efficient and green method for esterifying waxy maize starch (WMS).
• To investigate the use of an acidic deep eutectic solvent (CCHAc-ADES) for starch modification.
• To explore the formation mechanism of lauric acid starch esters.

Main Methods:

• Esterification of WMS using varying mass fractions of CCHAc-ADES with lauric acid.
• Characterization using 13C and 1H nuclear magnetic resonance spectroscopy, X-ray diffraction, and gel permeation chromatography.
• Analysis of WMS morphology, crystallinity, particle size, and hydrophobicity.

Main Results:

• Optimized conditions (70 wt% CCHAc-ADES) yielded starch esters with a high degree of substitution (0.161) and esterification efficiency (79.63%).
• CCHAc-ADES facilitated modification within WMS surface voids without significant structural damage.
• The formation mechanism involves competitive hydrogen bonding between CCHAc-ADES and WMS.

Conclusions:

• CCHAc-ADES is a favorable and green solvent for WMS chemical modification.
• The developed method enables the preparation of long-chain fatty acid starch esters sustainably.
• This study provides guidance for applying deep eutectic solvents in green synthesis.