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Preparation and characterization of non-crystalline granular starch and corresponding carboxymethyl starch

Zhang, Bao, Li, Xiaomin, Xie, Qiutao, Tao, Han, Wang, Wu, Chen, Han-Qing
International journal of biological macromolecules 2017 v.103 pp. 656-662
Silene chalcedonica, X-ray diffraction, corn starch, differential scanning calorimetry, ethanol, scanning electron microscopy, starch, temperature
Native corn starch slurried in 50% ethanol solution was treated at 60°C, 70°C, 80°C, and 85°C, respectively. The resultant starches were investigated by polarized microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The Maltese cross of ethanol-heating treated starch gradually weaken with increasing temperature and completely disappeared at 85°C. SEM data indicated the treated granular exhibited a rougher surface with more pores and grooves than native starch granular, but the shape of the treated starch was still intact. DSC and XRD data confirmed ethanol-heating treated starch changed from crystalline to non-crystalline structure at 85°C. The highest degree of substitution (DS) and corresponding reaction efficiency (RE) for the carboxymethylation of native starch were 0.66 and 36.7%, respectively, while the corresponding DS and RE for non-crystalline granular starches increased by 0.29 and 16.1% at the same reaction condition, respectively.