Carbohydrate structures as part of the melanoidin skeleton

Chemical degradation reactions were used for structural investigation of melanoidins formed from oligomer and polymeric carbohydrates and amino acids. The released products were detected qualitatively and quantitatively by HPTLC and HPAEC/PAD. As result of hydrolysis of melanoidin models formed under water-free reaction conditions, a considerable amount of carbohydrate theoretically incorporated into the melanoidin was found as glucose. In comparison, hydrolysis of models formed under aqueous reaction conditions resulted in smaller glucose releases. Results indicated that oligo- and polysaccharides reacted in the Maillard reaction preferentially as complete molecules at the reducing end under water-free reaction conditions. Hydrothermolytic degradations and retro-aldol reactions of carbohydrates were favored under aqueous reaction conditions leading to the formation of more reactive monosaccharides. The results could be explained with the postulated melanoidin structure, which is mainly built up from amino-branched sugar degradation products. (C) 2002 Elsevier Science B.V. All rights reserved.