Kinetic modelling of Amadori N-(1-deoxy-D-fructos-1-yl)-glycine degradation pathways. Part II--kinetic analysis.
A kinetic model for N-(1-deoxy-D-fructos-1-yl)-glycine (DFG) thermal decomposition was proposed. Two temperatures (100 and 120 degrees C) and two pHs (5.5 and 6.8) were studied. The measured responses were DFG, 3-deoxyosone, 1-deoxyosone, methylglyoxal, acetic acid, formic acid, glucose, fructose, mannose and melanoidins. For each system the model parameters, the rate constants, were estimated by non-linear regression, via multiresponse modelling. The determinant criterion was used as the statistical fit criterion. Model discrimination was performed by both chemical insight and statistical tests (Posterior Probability and Akaike criterion). Kinetic analysis showed that at lower pH DFG 1,2-enolization is favoured whereas with increasing pH 2,3-enolization becomes a more relevant degradation pathway. The lower amount observed of 1-DG is related with its high reactivity. It was shown that acetic acid, a main degradation product from DFG, was mainly formed through 1-DG degradation. Also from the estimated parameters 3-DG was found to be the main precursor in carbohydrate fragments formation, responsible for colour formation. Some indication was given that as the reaction proceeded other compounds besides DFG become reactants themselves with the formation among others of methylglyoxal. The multiresponse kinetic analysis was shown to be both helpful in deriving relevant kinetic parameters as well as in obtaining insight into the reaction mechanism.
Martins
Sara I F S
SI
Department of Agrotechnology and Food Sciences, Product Design and Quality Management Group, Wageningen University, P.O. Box 8129, 6700 EV, Wageningen, The Netherlands.
Van Boekel
Martinus A J S
MA
D019342:Acetic Acid / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D005561:Formates / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015416:Maillard Reaction; D008956:Models, Chemical; D011108:Polymers / Q000737:chemistry; D013696:Temperature; D013997:Time Factors
D002241:Carbohydrates; D005561:Formates; C466902:N-(1-deoxy-fructos-1-yl)glycine; D011108:Polymers; C011908:melanoidin polymers; C030544:formic acid; D019342:Acetic Acid; D005998:Glycine