Model studies on Maillard reactions

ABSTRACT MODEL STUDIES ON MAİLLARD REACTIONS Kudret AKPINAR M.S. in Chemistry Adviser: Prof. Dr. Güler AYRANCI May 2000, 83 pages The Maillard reaction is a reaction which takes place between amino acids and reducing sugars in foods and it has very complex reaction steps. The reaction that starts with these reactants countinues with dehydration, cyclization, condensation, isomerization and rearrangement steps and produces the final product nitrogen- containing polimers, called melanoidins. Maillard reaction creats many different tastes, aroma compounds and colors in foods and is effective especially in foods that are prepared by heating processes. There are many factors which affect Maillard reaction. These are, starting with temperature, the duration of heat application, pH, amount of moisture, types and ratio of the concentration of reactants, presence of electrolytes or any inhibitors. Many researches have been performed on Maillard reaction. Part of these are for the understanding of the kinetics of the reaction and the researchers prefer working on model systems for this purpose. In this work, the kinetics of the Maillard reaction between D-glucose monohydrate and the amino acids L-lysine, L-cysteine, L-alanine and L-serine have been studied and the additive effect of these amino acids were examined. Results have led to the conclusion that the activation energies for lysine /glucose, cysteine/glucose, alanine/glucose and serine/glucose model systems were 114.2±12 kj/mole, 123.5±12 kj/mole, 111.7+12 kj/mole, and 125.3+12 kj/mole, respectively. According to the values of the activation energies, reactivities of the amino acids studied were found as alanine « lysine > cysteine « serine; which are reasonably in aggreement with other works. Amino acids were not found to show a clear additive effect in these reactions. KEY WORDS: Maillard Reactions, Nonenzymatic Browning Reactions, Maillard Model Systems. COMMITTEE: Prof. Dr. Güler AYRANCI Prof. Dr. Tevfık BARDAKÇI Prof. Dr. Muharrem CERTEL