紫茉莉籽淀粉的物化特性研究

Physicochemical properties of starch from Mirabilis jalapa L. seed

以紫茉莉籽为原料提取淀粉,研究其物化特性,并与玉米、马铃薯、绿豆等淀粉进行比较,为紫茉莉籽的应用提供一定的依据。采用物理化学方法、以流变仪、质构仪等研究了紫茉莉籽淀粉的直链淀粉含量、糊透明度、溶解率、膨胀势、冻融稳定性、糊化特性、流变特性和质构特性。结果表明:紫茉莉籽淀粉的直链淀粉含量为23.6%,与玉米淀粉相当(23.7%),显著低于马铃薯淀粉(28.5%)和绿豆淀粉(37.1%);紫茉莉籽淀粉糊透明度、溶解率和膨胀势分别为0.6%、2.3%和9.1%,均小于其他三种淀粉,且其冻融稳定性最差。紫茉莉籽淀粉的糊化温度最大,为73.8℃;显著高于马铃薯淀粉和绿豆淀粉;紫茉莉籽淀粉两浓度下(6%和8%)的峰值黏度、保持黏度、最终黏度、降落值和回生值均小于其他三种淀粉,且降落值较小(0.01Pa·s),回生值/峰值黏度较大;紫茉莉籽淀粉流变指数为0.724和0.738,属于假塑性流体,且呈现剪切稀化现象。紫茉莉籽淀粉的凝胶强度略大于马铃薯淀粉;但其硬度、弹性、黏聚性、胶黏性、咀嚼性和回复性均小于其他三种淀粉。结论:紫茉莉籽淀粉颗粒不易吸水膨胀,糊化后透明度小,冻融稳定性差,黏度低,且不易形成凝胶。

Starch was obtained from Mirabilisjalapa L. seed, and the physicochemical properties were comparatively studied with corn starch, potato starch and mung bean starch. Amylose content, paste transparency, solubility, swelling power, freeze-thaw stability, gelatinization properties, rheological properties and texture properties of Mirabilis jalapa L. seed starch were studied by physical and chemistry analysis, rheometer and texture analysis. The results showed that the amylose content of Mirabilis jalapa L. seed starch was 23.6% which was similar to that of corn starch （23.7%）and significantly lower than that of potato starch and mung bean starch （28.5%） （37.1%）. Paste transparency, solubility and swelling power of Mirabilis jalapa L. seed starch were 0.6%, 2.3% and 9.1%, respectively, and were less than those of the other three starches. The freeze-thaw stability of Mirabilisjalapa L. seed starch was the worst. Gelatinization temperature of Mirabilisjalapa L. seed starch was 73.8 ℃, which was the largest and significantly higher than that of potato starch and mung bean starch. All of peak viscosity, hot paste viscosity, final viscosity, breakdown viscosity and setback viscosity of Mirabilisjalapa L. seed starch at concentration 6% and 8% were less than those of the other three starches, especially the breakdown viscosity （0.01Pa·s）. However, the setback viscosity was higher than that of other starches. Rheological index of Mirabilis jalapa L. seed starch were 0.724 and 0.738, which indicating it was pseudoplastic fluidand presented the phenomenon of shear thinning. The gel strength of Mirabilisjalapa L. seed starch was slightly higher than that of potato starch, but its hardness, springiness, cohesiveness, gumminess, chewiness and resilience were less than those of the other three starches.The conclusions of Mirabilis jalapa L. seed starch were poor water absorption, low transparency after pasting, poor freeze-thaw stability and lower viscosity, andhard to form gel.