Synthesis of Itaconate Finger Millet Starch Ester Via Solvent‐Free Technique: Evaluation of Physicochemical, Structural, and Thermal Properties

The present study introduces a solvent‐free technique to modify finger millet starch (FS) via reaction with itaconic acid (IA) at concentrations ranging from 3.0% to 8.0%, coupled with dry heat treatment (DHT) at 130°C for 3 h. The combined IA/DHT modification markedly reduced the moisture content of native FS from 12.09 ± 0.6% to as low as 0.242 ± 0.07%, while the amylose content increased from 39.03% ± 0.6% to 41.24% ± 0.05%. SEM revealed pronounced surface dents and pits, indicating structural disruption of the starch granules. XRD analysis confirmed the retention of A‐type crystalline structure, along with the emergence of a new peak at 21.42°, suggesting the formation of an IA–FS complex. FTIR further validated esterification through the appearance of a distinct carbonyl (C═O) stretching band at 1732 cm − 1 , confirming covalent linkage between starch hydroxyl groups and IA carboxyl groups. TGA demonstrated enhanced thermal stability, with initial mass loss reduced from 12% to 5% and residual char content increased from 5% to 17% following modification. These findings highlight the efficacy of this green, solvent‐free dry heat approach for synthesizing starch itaconates with improved structural and thermal properties.