丙烯酰胺
美拉德反应
化学
反应速率常数
水活度
动力学
反应速率
天冬酰胺
消除反应
化学动力学
含水量
热力学
有机化学
催化作用
聚合物
量子力学
物理
工程类
共聚物
酶
岩土工程
作者
Kristel De Vleeschouwer,Iesel Van der Plancken,Ann Van Loey,Marc Hendrickx
摘要
The influence of water activity on the kinetics of acrylamide formation and elimination reaction was investigated using low-moisture equimolar asparagine-glucose model systems, which were heated at temperatures between 120 and 200 °C for variable heating times. To determine the water content corresponding to the water activities tested, a sorption moisture isotherm was constructed experimentally. The acrylamide concentrations measured at different water activities could be modeled on the basis of a reaction scheme including not only acrylamide formation and elimination reactions but also an alternative Maillard reaction between both reactants. The corresponding rate constants and activation energies were estimated using nonlinear regression analysis. Whereas the rate constant for acrylamide formation varied only slightly with the initial water activity of the model system, the elimination rate constant showed a clear minimum around a water activity of 0.82. The opposite trend, namely, a maximum at a water activity of 0.82, was found for the Maillard reaction rate constant as a function of water activity, which confirms data from literature. The activation energies for the different reactions changed in a comparable way as the corresponding rate constant with water activity.
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