Isolation and structural analysis of maillard polymers: caramel and melanoidin formation in glycine/glucose model system

A water-methanol solution of glycine and d-glucose was refluxed at 65 °C for seven h. The solvent was evaporated under vacuum at room temperature and the residue was dialyzed against distilled water. After dialysis, the solvent was evaporated under vacuum at room temperature. The non-dialyzable fraction was further fractionated by gel filteration. The process yielded three polymeric materials (10 000 < MW < 20 000) termed A, B1 and B2. The isolated polymers were further analyzed by UV-VIS and FTIR spectroscopy and by pyrolysis/GC/MS. Elemental analysis indicated that polymer A has the following empirical formula C7H11N1O4 and polymers B1 and B2 have the same empirical formula as d-glucose (C1H2O1). The origin of nitrogen containing polymer A was assigned to Amadori intermediate or to its derivatives and the origin of polymers B1 and B2 was assigned to glucosone and/or to 3- or 1-deoxyglucosones; common non-nitrogen containing reactive intermediates formed during the Maillard reaction. Plausible mechanisms were proposed for the formation of polymers based on spectroscopic data.