红薯/玉米淀粉共混物糊、流变及热力学性质研究

Study on the pasting,rheological and gelatinization properties of sweet potato/corn starch blend

以不同质量比(0100,2575,5050,7525,1000)的红薯/玉米淀粉混合物为原料,用不同试验方法研究其糊化及流变学特征。布拉班德糊化结果表明:玉米淀粉成糊温度(77.7℃)高于红薯淀粉(73.2℃),红薯淀粉峰值黏度(513BU)大于玉米淀粉(281BU),混合淀粉的崩解值及回生值介于单一种类淀粉之间;动态频率扫描结果表明:玉米淀粉的储能模量约是红薯淀粉的4倍,混合淀粉的模量介于单一品种淀粉之间,均为弱凝胶;稳态流变曲线表明:被测样品符合Herschel-Bulkley模型,均为非牛顿型流体,相较于单一淀粉,红薯/玉米淀粉混合物触变性假塑性更强。剪切结构恢复力结果表明:红薯/玉米混合物淀粉凝胶抗剪切能力低于玉米淀粉。差示扫描量热(Differential scanning calorimetry,DSC)测定结果表明:玉米淀粉具有较高的热焓值,红薯/玉米混合淀粉热焓值降低。

This research studied the characteristics of paste,rheology and gelatinization of sweet potato/maize starch mixtures in different proportions(0100;2575;5050;7525;1000).The pasting results showed that the pasting temperature of corn starch(77.7℃)was higher than that of sweet potato starch(73.2 ℃),and the peak viscosity of sweet potato starch(513 BU)was greater than that of corn starch(281 BU);The breakdown and setback were in between two kinds of starch.The dynamic frequency scanning tests showed that the elastic modulus of corn starch was about four times as that of sweet potato starch,and the modulus of mixed starch was between that of a single variety.The steady-state rheological curve showed that all the tested samples conformed to the Herschel-Bulkley model and were non-newtonian fluids with shear dilute behavior;Comparing with single starch,thixotropy and pseudoplastic of sweet potato/corn starch mixture increased;The anti-shear ability of starch gel of sweet potato/maize mixture was lower than that of corn starch.Results of differential scanning calorimetry(DSC)indicated that corn starch had higher gelatinization temperature and enthalpy value than the others.