Role of precursors on the kinetics of acrylamide formation and elimination under low moisture conditions using a multiresponse approach - Part II: Competitive reactions

The effect of addition of amino acids, other than asparagine, on the kinetics of acrylamide formation and elimination reactions was investigated under low moisture conditions using equimolar asparagine-glucose-amino acid model systems, heated at temperatures between 120 and 200 degrees C. To this end, glutamine and cysteine were selected. A mechanistic model was proposed, composed of the basic reactions occurring in an asparagine-glucose control system on the one hand and of extra reactions in which the additional amino acids are assumed to be involved. Using this model, multiresponse modelling was applied on the responses measured (the same as before plus the concentration of the second amino acids added). In order to test the consistency of the basic model and to elucidate the mechanism(s) by which the additional amino acids act on acrylamide formation and elimination, the kinetic parameters for the different reaction steps of the basic model were fixed to the values estimated for the control system. Addition of glutamine had a slightly increasing effect on the yield of acrylamide, resulting in a significant increased rate constant for acrylamide formation and elimination. Cysteine on the contrary, had a pronounced reducing effect (>99%) on the acrylamide yield, which can mainly be attributed to an additional acrylamide elimination reaction which is dependent on the cysteine concentration. (C) 2008 Elsevier Ltd. All rights reserved.