Colour assays have been used to evaluate heat effects induced during the processing of ready to eat cereals. The cereal flakes were made of wheat flour, rice flour and yellow corn meal. Model systems comprising starch, glucose and amino acids were also included in this study.  Glutamine, lysine, proline and asparagine were used in this study The colour changes in the cereal flakes as well as in the model systems were followed up over a heating period of 180 minutes at 100°C. Three methods were used to detect colour changes being: spectrophotometeric absorbance, tristimulus colorimetric and sensory evaluations. Tristimulus colorimetric evaluation was based on CIELAB uniform space L*,a* and b*, where L* stands for "lightness", a* for "redness" and b* for "yellowness" The results have indicated that the rate of browning of the model system containing lysine was much greater than that in case of systems containing glutamine, proline or asparagine. The rate of browning of the three cereal flours used in this study were increased in the following order; rice < wheat < corn. The results have shown that the changes in the lightness L* of the cereal flakes or the model systems with heating time follow first order kinetics. However, the change in the redness a* and the browning index due to the development of the brown pigments follow zero order kinetics. The combination of the parameters (L*a*/b*) were used successfully to evaluate a total colour change with time and it followed zero-order kinetics.