超声处理对小米淀粉结构及理化性质的影响

Effects of Ultrasonic Treatment on the Structure and Physicochemical Properties of Millet Starch

在相同超声温度及时间下,研究了不同超声功率0、25、50、100、150、200、250 W对小米淀粉聚集态结构及理化性质的影响,测定了超声处理时小米淀粉的水解率、颗粒形貌、晶体结构、官能团结构、粒径大小、流变学特性、糊化特性的变化规律。结果表明:超声处理导致小米淀粉水解率和粒径增大,250 W超声处理40 min小米淀粉水解率为1.037%,平均粒径由9.96μm增大到12.10μm,且表现出更好的稳定性;超声处理未引起小米淀粉结晶类型和分子结构改变,但导致分子有序度略微下降;超声处理改变了小米淀粉糊的流动性,其剪切应力和表观黏度随超声功率增加而降低;小米淀粉在超声处理后峰值粘度、最低粘度、终值粘度、崩解值和回生值均显著降低,热稳定性增加。超声波技术广泛应用于变性淀粉加工,本研究的结果可为小米淀粉的改性研究提供理论基础。

With the same ultrasonic time and temperature, different ultrasonic powers of 0, 25, 50, 100, 150, 200, 250 W on the structure and properties of millet starch were studied. The hydrolysis rate, microstructure, crystal structure, molecular structure, particle size, rheological and gelatinization properties of millet starch were determined. The experimental results indicated that the hydrolysis rate and particle size of millet starch increased after ultrasonic treatment,hydrolysis rate of millet starch under 250 W ultrasonic treatment for 40 min was 1.037%, the average particle size increased from the original 9.96 to 12.10 μm, and it showed greater transparency and stability. Ultrasonic treatment did not change the crystal type and molecular structure, but caused a slight decrease in order. Ultrasound changed the fluidity of millet starch paste, the shear stress and apparent viscosity of millet starch paste decreased with the increase of ultrasonic power. The peak viscosity,trough viscosity, final viscosity, breakdown and setback of millet starch after ultrasound were significantly reduced, and the thermal stability was improved. Ultrasonic technology would be widely used in the processing of modified starch. The results of this study could provide a theoretical basis for the modification of millet starch.