直链淀粉含量对玉米淀粉/瓜尔胶复配体系糊化和流变特性的影响

为考察直链淀粉含量对淀粉/瓜尔胶复配体系性质的影响,以不同直链淀粉含量的玉米淀粉(蜡质玉米淀粉、普通玉米淀粉和高直链玉米淀粉)为原料,加入瓜尔胶,研究复配体系的糊化、流变及凝胶特性。结果表明:瓜尔胶与直链淀粉之间的相互作用是引起淀粉复配体系黏度和稠度系数增加、成糊温度和流体指数降低的主要原因。动态流变实验结果表明淀粉中直链淀粉含量不同对复配体系的动态模量的影响也不同。在糊化过程中,随着直链淀粉含量增加,直链淀粉分子与瓜尔胶间的相互作用增强,阻碍了直链淀粉分子间的聚集重排,使得复配体系硬度值减小,3种玉米淀粉形成了质地更为柔软的凝胶。

Effect of Amylose Content on the Pasting and Rheological Properties of Corn Starch/Guar Gum Mixtures

The effect of amylose content on pasting and rheological properties of corn starches(waxy,normal and high-amylose corn starch)/guar gum mixtures were studied. The mechanism of interaction between amylose and guar gum was also analyzed. Rapid visco-analysis(RVA) data showed that guar gum addition increased the peak,breakdown,final,and setback viscosities of starches. This effect was more pronounced for normal corn starch than waxy corn starch. The pasting temperature of the waxy corn starch /guar gum mixtures was higher than the control,while quite an opposite result was obtained,for the normal corn starch,where the addition of guar gum lowered the pasting temperature. Flow tests showed that all pastes exhibited time-dependent shear-thinning (thixotropic) with yield stress behavior in which the hysteresis loop areas were significantly decreased by guar gum addition,whereas the other rheological parameters varied differently among the samples. The results could be attributed to interactions between the hydrocolloids molecules and amylose molecules. Dynamic shear data revealed that weak gel-like behavior in all paste samples,and dynamic modulus of each system responded to guar gum in a different way,depending on the amylose content of corn starch. The amylose content is higher,the effect of interactions between amylose and gum is more significant. This effect led to all mixed gels softer.