脱乙酰魔芋葡甘聚糖对马铃薯淀粉糊化及流变性质的影响

以马铃薯淀粉为原料,向其中添加脱乙酰度分别为20%、45%、70%、90%的魔芋葡甘聚糖,研究复合体系的糊化及流变性质。结果表明随着魔芋葡甘聚糖脱乙酰度增加,复合体系的糊化温度略向高温移动,从66.0℃增加至66.5℃,糊化焓值从10.1J/g下降至8.9J/g。静态流变学实验表明,脱乙酰魔芋葡甘聚糖-马铃薯淀粉体系为假塑性非牛顿流体,呈现明显剪切稀化现象。Power-law方程拟合发现,随着魔芋葡甘聚糖脱乙酰程度增大,复合体系稠度系数k值从128.8上升至694.4,流动特性指数n值从0.4711下降至0.3879。动态流变学实验表明,当魔芋葡甘聚糖脱乙酰度从20%增加至90%,复合体系凝胶强度的An值从236.7增加至2468.9。说明高脱乙酰度魔芋葡甘聚糖对马铃薯淀粉凝胶强度贡献明显。

Effects of Deacetylated Konjac Glucomannan on Gelatinization and Rheological Properties of Potato Starch

Konjac glucomannan with different deacetylation degrees of 20%,45%,70% and 90% was added to the raw material potato starch to form mixture.The gelatinization and rheological properties of the mixture were studied.The results showed that as the deacetylation degree of konjac glucomannan increased,the gelatinization temperature of the mixture shifted slightly to a higher temperature( from 66.0 ℃ to 66.5 ℃),and the gelatinization enthalpy went down from 10.1 J /g to 8.9 J /g. Static rheological results showed that the mixture made of deacetylated konjac glucomannan and potato starch was a pseudoplastic non-Newtonian fluid with an obvious shear thinning phenomenon.The power law equation fitting results found that with the increasing of the deacetylation degree of konjac glucomannan,the k value of the consistency coefficient of the mixture increased from 128.8 to 694.4,and the flow characteristic index n value declined from 0.4711 to 0.3879.Dynamic rheological results presented when the deacetylation degree of konjac glucomannan increased from 20% to 90%,the An value representing the gel strength of the mixture increased from 236.7 to 2468.9.It indicated that konjac glucomannan with a higher deacetylation degree contributed significantly to the gel strength of the mixture.