Effect of Amylose Content on the Physicochemical Properties of Hydroxypropyl-Oxidized Corn Starches
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Abstract:
Waxy corn (WC), common corn (CC), and high-amylose cornstarches (AMC) were used as the raw materials in this study, and different amounts of chlorine were used to prepare hydroxypropyl-oxidized starches. The effect of amylose content on the physicochemical properties of hydroxypropyl-oxidized starches was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Brabender viscosity analysis. The results indicated that high amylose content favored hydroxypropylation, but was not conducive to oxidation. The XRD observations showed that the crystal type was not changed in the modified starches. With increasing degrees of oxidation, the crystallinity of starch molecules decreased, and the decreasing tendency slowed down with increasing amylose content. DSC and Brabender viscosity analysis indicated that amylose content directly affected the gelatinization and paste properties of hydroxypropyl-oxidized starches. The gelatinization temperatures, viscosities, and gelatinization enthalpies of the three starches were in the following orders: gelatinization temperature: AMC > CC > WC, viscosity: WC > CC > AMC, and gelatinization enthalpy: WC > CC > AMC. Observation of the starch properties under polarized light and the surface morphology of starch granules showed that a high amylose content led to a weak polarization intensity for hydroxypropyl-oxidized starches, and starch granules that were not easily cracked.
