Characterization the structural property and degradation behavior of corn starch in KOH/thiourea aqueous solution
2021
Li, Wenwen | Li, Jinge | Cheng, Li | Gu, Zhengbiao | Sun, Chunrui | Hong, Yan
Finding an efficient and eco-friendly solution for starch dissolution has attracted considerable attentions in recent years. This study investigated the structural characteristics, and degradation behavior of corn starch in KOH/thiourea aqueous solution by the comparison with DMSO/LiBr and 1-allyl-3-methylimidazolium chloride (AMIMCl). Results showed that KOH/thiourea solution was an effective solvent for corn starch dissolution (30 min with 97.01% solubility). X-ray diffraction (XRD) and ¹³C CP-MAS NMR spectroscopy revealed that native crystallinity of the corn starch was altered by all tested solvents, especially DMSO/LiBr and AMIMCl. Conversely, this new solvent did not change the primary molecular structure, chain-length distribution, or thermal stability of starch, compared with the native starch. Furthermore, KOH/thiourea solution was more suitable for measuring the molecular weight of corn starch, with a weight-average molecular weight (Mw) of 7.18 × 10⁷ g/mol. Therefore, KOH/thiourea solution is a promising novel solvent for starch dissolution and structural exploration.
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