Formation of a novel colored product during the Maillard reaction of D-glucose

Reactions between reducing sugars and proteins or amino acids (Maillard rea ction) lead to the formation of yellow to brown products (melanoidins) that are important for food preparation and processing, such as baking, roastin g, or malt production. Thus far, the structures of the melanoidins have not been elucidated, although some structural insights have been gained from m odel reactions. In this study, D-glucose was heated with an amine and two c olored compounds were detected by HPLC/UV-vis. After purification, the main product was identified as [(4aS,6R,7S,8R,8aR)-4,4a,6,7,8,8a-hexahydro-7,8- dihydroxy-6-hydroxymethyl-1,4-dipropyl-1H-pyrano[2,3-b]pyrazine-2-yl]-1-hyd roxy-3-buten-2-one (la). For the minor compound (2a), some spectral data we re obtained, but the structure was not fully characterized. la and 2a are t he main colored compounds when the reaction is performed in alcoholic solut ion or on a cellulose surface. Thus, it was concluded that products with an analogous structure are important for the color formation of foodstuffs wi th low water activity.