title: Kinetics of acrylamide formation/elimination reactions as affected by water activity.
abstract: 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 degrees 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.
authors.affiliation: Laboratory of Food Technology, Center for Microbial and Food Technology, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Heverlee, Belgium.
authors.forename: Kristel
authors.initials: K
authors.lastname: De Vleeschouwer
authors.forename: Iesel
authors.initials: I
authors.lastname: Van der Plancken
authors.forename: Ann
authors.initials: A
authors.lastname: Van Loey
authors.forename: Marc E
authors.initials: ME
authors.lastname: Hendrickx
mesh_terms: D020106:Acrylamide / Q000737:chemistry*; D000465:Algorithms; D001216:Asparagine / Q000737:chemistry; D006361:Heating; D007700:Kinetics; D012044:Regression Analysis; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D020106:Acrylamide; D001216:Asparagine