Kinetics of color changes due to maillard reaction in model food systems

ABSTRACT KINETICS OF COLOR CHANGES DUE TO MAILLARD REACTION IN MODEL FOOD SYSTEMS BOZKURT, Hüseyin M. Sc. in Food Engineering Supervisor: Assoc. Prof. Dr. EREN, Sami June 1996, 71 pages The nonenzymic browning reactions in models, Pekmez and Pekmez containing model systems were studied. The effects of sugars (D-fructose, D-glucose) and type of amino acids (L-glutamine, L-arginine and L-proline) on both 5-HMF accumulation and brown pigment formation in all these systems were investigated at three different temperatures during 10 days period. It was observed that, 5-HMF accumulation at pH 3.5 and brown pigment formation at pH 6.0 were the highest in Pekmez containing model systems. D-fructose was the major sugar for the formation of 5-HMF and brown pigment in all systems. With fructose as a substrate, 5-HMF and brown pigment formed faster in the presence of L- glutamine than in the presence of L-arginine and L-proline in the systems. Reaction orders were found as 0.5 for 5-HMF accumulation, zero for brown pigment formation in all samples by using the non-linear regression analysis.. Rate constants were determined for 5-HMF accumulation by using non-linear regression analysis and linear regression analysis for brown pigment formation. Activation energies of model systems, Pekmez and Pekmez containing model systems were found in the range of 52.68-265.40 kj/mol for 5-HMF accumulation and 41.46- 217.08 kj/mol for brown pigment formation. Key Words : Nonenzymic browning reaction, 5-Hydroxymethyl furfural (5-HMF), Fructose, Glucose, Glutamine, Arginine, Proline, Pekmez.