发芽小米淀粉热分解机制及动力学研究

发芽是改善谷物品质的绿色加工方法。为了探究发芽对小米淀粉热力学性质的影响,采用差示量热扫描法、热重分析法对发芽小米淀粉的热分解机制及其动力学行为进行了研究。结果表明,小米发芽后淀粉糊化温度升高,糊化焓、回生度、回生速率均减小;未处理及发芽处理小米淀粉热分解均是一个连续的过程,热分解温度范围为295~360℃,分解速率最快的温度范围为298.49~305.01℃;发茅小米淀粉活化能、指前因子、焓值、熵值(绝对值)及吉布斯自由能均较未处理小米淀粉减小;未处理及发茅小米淀粉热分解最概然机制函数均为G(α)=lnα,最概然机制为单分子消除反应,为一级反应。

Effect of Germination on Thermal Decomposition Mechanism and Kinetics of Millet Starch

Germination was a green processing method to improve grain quality.The thermal decomposition mechanism and dynamic behavior of germinated millet starch were studied by differential calorimetry scanning and thermogravimetry technologies.The results showed that the starch gelatinization temperature increased after millet germination,the gelatinization enthalpy,reversion degree,and reversion rate all decreased.The thermal decomposition of germinated and raw millet starch conformed to the law of continuous process.The thermal decomposition temperature range was 295~360℃,the fastest temperature range of decomposition rate was 298.49~305.01℃.Activation energy,pre-factor,enthalpy,entropy(absolute value) and Gibbs free energy of germinated millet starch were all lower than those of raw millet starch.For the germinated and raw millet starch,the most probable reaction mechanism functions of the thermal decomposition were G(a)=Inα,the most probable reaction mechanisms were single-molecule elimination reaction,which were first-order reaction.