Fragmentation of Sugar Skeletons and Formation of Maillard Polymers

Abstract

Labelling experiments involving the reaction of 13 C-labelled hexoses, pentoses, and D-lactose with 4-aminobutyric acid (GABA) are described. The distribution of the label was investigated by MS and gave an insight into the formation pathways leading to complementary labelled compounds from hexoses and pentoses with intact carbon skeletons and indicated distinct fragmentations of the sugar skeletons into C 5 -and C 4 -compounds (furans, N-alkylpyrrolemethanols, N-alkyl-2-formylpyrroles and N-alkylpyrroles). These compounds undergo polycondensations to melanoidin-like macromolecules under mild reaction conditions. In a series of model experiments, different types of polymers were investigated, and individual oligomers were characterized by 1 H/ 13 C-NMR spectroscopy and FAB-/MALDI-TOF-MS. We postulate that these polycondensation reactions represent the most important driving force in the Maillard reaction.