高压微射流改性聚葡萄糖对大米淀粉凝胶老化的影响

Effect of Dynamic High Pressure Microfluidization Modified Polydextrose on Retrogradation of Rice Starch Gel

为了解改性聚葡萄糖对大米淀粉凝胶老化的影响,采用动态高压微射流技术在80、120、170 MPa下对聚葡萄糖进行了改性,利用激光粒度仪和高效液相色谱仪测定改性聚葡萄糖粒径和相对分子质量,并用快速黏度分析仪(RVA)、差示扫描量热仪(DSC)、X-射线衍射仪、质构仪和扫描电镜测定添加改性聚葡萄糖(MPD)的大米淀粉凝胶老化特性。结果表明,动态高压微射流处理使聚葡萄糖平均粒径显著减小,相对分子质量降低。随压力增大,聚葡萄糖相对分子质量降低,大米淀粉糊回生值均显著下降,表明改性聚葡萄糖可以有效地延缓大米淀粉凝胶的短期老化;随着处理压强的增大,大米淀粉凝胶老化焓值、相对结晶度和硬度均显著降低,大米淀粉凝胶网络孔洞更加密集,孔径更加细小,表明MPD可以抑制大米淀粉凝胶的长期老化,且改性压强为120 MPa时,大米淀粉凝胶老化率降低了1.93%,相对结晶度降低了1.42%。由此表明动态高压微射流改性后的聚葡萄糖可以更好抑制大米淀粉凝胶的老化。

In order to investigate the influence of modified polydextrose on the retrogradation of rice starch gel,polydextrose were modified by dynamic high pressure microfluidization(DHPM)at 80,120 and 170 MPa,respectively.Particle size and molecular weight of modified polydextrose were analyzed by laser particle size and high-performance liquid chromatography.Effect of modified polydextrose on the retrogradation of rice starch gel were investigated by using Rapid viscosity analyzer(RVA),differential scanning calorimeter(DSC),X-ray diffractometer,texture analyzer and scanning electron microscopy(SEM).The results indicated that the average particle size and molecular weight of polydextrose decreased significantly.The addition of modified polydextrose significantly decreased the setback values of rice starch,which meant that the short-term retrogradation of rice starch was inhibited.The retrogradation enthalpy,relative crystallinity and hardness decreased significantly with the increase of pressure.The rice starch gel network has more dense pores and a smaller pore size.These results indicated that the long-term retrogradation of rice starch gel was inhibited.The aging ratio of rice starch gel significantly decreased from 30.64%to 28.71%,with a decrease of 1.93%,the relative crystallinity of rice starch gel significantly decreased from 12.85%to 11.43%,with a decrease of 1.42%,at 120 MPa.It could be concluded that the addition of modified polydextrose apparently influenced not only the short-term retrogradation of amylose,but also the long-term retrogradation of amylopectin.