A KINETIC-MODEL FOR ACCELERATED TESTS OF MAILLARD BROWNING IN A LIQUID MODEL SYSTEM

The feasibility of a novel approach to accelerated storage tests was e valuated for Maillard browning of a glucose-glycine model system. This approach is based on use, in addition to external conditions such as temperature, of composition to accelerate the rate of deterioration. R eactant concentration, and catalysts are not affected by storage condi tions but still can be used to obtain a high rate of deterioration. Th ey can be, therefore, an important part of accelerated tests procedure s provided that one establishes first the comprehensive kinetic model that includes the effect of all the factors that are used. For a gluco se-glycine model system, a comprehensive kinetic model was evaluated f or a wide range of conditions (reactants concentration 0.0625-2 M, cop per ions up to 50 ppm, pH 4-8 and temperatures 30-61 C) and found to h ave an apparent order of reaction of 0.8 (representing the combined ef fect of a first order induction period and the following zero order ph ase). All the factors that were used are capable of affecting the rate of reaction. The kinetic model was found to be a simple four paramete r equation where the effect of the pH is manifested mainly through the level of the unprotonated form of the amino acid. However copper ions have a relatively small effect and thus could be eliminated from the model. Without the copper, the kinetic model is a very simple three pa rameter equation that can be easily evaluated by accelerated tests and used to extrapolate the data to normal storage conditions.