Maillard browning kinetics

Amadori compounds (N-substituted-l-amino-l-deoxy-2-ketoses) are potential precursors to the formation of many of these heterocyclic volatile products. The secondary nitrogen in most Amadori compounds is weakly basic and is therefore a likely site for rapid nitrosation reactions via normal reactions with nitrous acid, under mildly acidic conditions. However, purified Amadori compounds are usually obtained only after tedious isolation procedures are invoked to separate them from the complex mixtures of typical Maillard browning systems. Takeoka et al. ( 5) reported high performance liquid chromatographic (HPLC) procedures to separate Amadori compounds in highly purified form on a wide variety of columns, both of hydrophilic and hydrophobic nature. They were able to thus demonstrate that reaction products could be followed for kinetic measurements as well as to ensure purity of isolated products. 

G. A. Reineccius, Kinetics of flavor formation during Maillard browning, in Flavor Chemistry Thirty Years of Progress, R. Teranishi, E. L. Wick, and I. Homstein (eds), Kluwer Academic/Plenum, New York, 1999, 345-352. 

E.-H. Ajandouz and A. Puigserver, Nonenzymatic browning reaction of essential amino acids effect of pH on caramelization and Maillard reaction kinetics, J. Agric. Food Chem., 1999, 47, 1786-1793. 

Researchers who use the very complex Maillard browning reaction to study the significance of moisture, Tg and a should be familiar with the complicated pathways, feedback inhibitions, and intermediates that are inherent to the reaction (Hodge, 1953) before validating kinetic data and drawing conclusions as to the mechanism for the influence of moisture on the reaction. Other than the aforementioned considerations, such as matrix... 

The formation of brown pigments via the Maillard reaction, especially in model systems (e.g. glucose-glycine), usually follows zero-order kinetics, but the loss of reactants has been found to follow first- or second-order kinetics in foods and model systems. Activation energies of 109, 116 and 139 kJ mol-1 have been reported for the degradation of lysine, the formation of brown pigments and the production of hydroxymethylfurfural (HMF), respectively. 

C. M. Brands and M. A. J. S. van Boekel, Kinetic modelling of Maillard reaction browning effect of heating temperature, in Melanoidins in Food and Health, Vol. 2, J. M. Ames (ed), European Communities, Luxembourg, 2001, 143-144. 

Saltmarch, M., Vagnini-Ferrari, M., and Labuza, T.P., Theoretical basis and application of kinetics to browning in spray-dried whey food systems, in Maillard Reactions in Food, Eriksson, C., Ed., Pergamon Press, Oxford, 1981, p. 331. 

Piergiovanni, L., de Noni, I., Fava, P., and Schiraldi, A. (1989). Nonenzymatic browning in processed cheeses. Kinetics of the Maillard reaction during processing and storage. Ital. J. Food Sci. 1,11-20. 

In our investigation on the effect of Maillard reaction products on the absorption of tryptophan (36), the kinetics of the absorption of tryptophan in the presence of Maillard reaction products formed in the glucose-tryptophan system was studied by bott vitro everted gut sac method and vivo catherization of the portal vein. Fructose-L-tryptophan (Amadori compound) appeared to be the major fraction of the reaction products when fractionated using a cellulose column eluted by water-saturated n-butanol. The absorption of L-tryptophan was partially inhibited vitro and vivo by fructose-L-tryptophan in a competitive manner with an inhibitor constant (Ki) of l.lmM. The relative absorption rate of L-tryptophan was significantly lower in the presence of the Maillard reaction products than in the presence of fructose-L-tryptophan indicating the presence of other inhibitory factors in the reaction products. The in vivo absorption of fructose-L-tryptophan was almost negligible compared to that of tryptophan. The inhibited absorption by Maillard reaction products, may have contributed in part to an incomplete recovery in the growth of the rats when fed a supplemented browned synthetic amino acid diet. 

These results were consistent with the earlier work of Warbier et al. (20) and Labuza et al. (21) who found that formation of browning products in the Maillard reaction gener ly followed pseudo zero order kinetics when reactant concentrations were in excess. 

It has been reported [54] that the production of water during the Maillard reaction, which is not produced during crystallisation, can be used to determine the kinetics of non-enzymatic browning and distinguish between the two processes. 

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