微波辐射下蜡质玉米淀粉性质的变化

Property Variation of Waxy Maize Starches Radiated with Microwave

采用微波对含水量为30%的蜡质玉米淀粉进行处理,运用扫描电子显微镜、X射线衍射仪、差示扫描量热仪以及布拉本德粘度仪等对微波辐射前后淀粉的物化性质进行了研究.结果表明:经微波辐射的淀粉颗粒表面会出现小孔和凹坑;微波辐射增强了对应的X射线衍射峰的强度,降低了玉米淀粉的膨胀度、溶解度、冻溶稳定性以及焓值,提高了糊化转变温度及其范围;蜡质玉米淀粉经处理后,其糊化起始温度升高,粘度降低,但粘度曲线不改变.以上结果表明,在淀粉颗粒内无定形区和结晶区的直链淀粉与直链淀粉之间、直链淀粉与支链淀粉之间会发生交互作用,产生新的不同稳定性的结晶体,从而使淀粉内部出现更加有序的结晶排列.

Waxy maize starches with a moisture content of 30% were treated with microwave radiation. The properties of the native and the treated starches were then studied by using SEM, XRD, DSC and Brabender viscoamylograph. It is indicated that （ 1 ） after the radiation, the surfaces of the starches become porous with concavity ; （2） microwave radiation enhances the X-ray intensities of the starches, decreases the swelling power, solubility, syneresis and gelatinization enthalpy of the starches, and improves the gelatinization transition temperature and the corresponding range; and （3） the waxy maize starches treated by microwave is of an increased pasting temperature and a decreased viscosity with the viscosity pattern remains unchanged. The above-mentioned details reveal the interaction involving starch chains （amylose-amylose and amylose-amylopectin） in the amorphous and crystalline regions of the granules, which results in the formation of new crystallites with different stabilities and more ordered crystalline array in the starches.