title: D-Galacturonic Acid: A Highly Reactive Compound in Nonenzymatic Browning. 2. Formation of Amino-Specific Degradation Products.
abstract: Thermal treatment of aqueous solutions of D-galacturonic acid and L-alanine at pH 3, 5, and 8 led to rapid and more intensive nonenzymatic browning reactions compared to similar solutions of other uronic acids and to Maillard reactions of reducing sugars. The hemiacetal ring structures of uronic acids had a high impact on browning behavior and reaction pathways. Besides reductic acid (1,2-dihydroxy-2-cyclopenten-1-one), 4,5-dihydroxy-2-cyclopenten-1-one (DHCP), furan-2-carboxaldehyde, and norfuraneol (4-hydroxy-5-methyl-3-(2H)-furanone) could be detected as typical products of nonenzymatic uronic acid browning reactions. 2-(2-Formyl-1H-pyrrole-1-yl)propanoic acid (FPA) and 1-(1-carboxyethyl)-3-hydroxypyridin-1-ium (HPA) were identified as specific reaction products of uronic acids with amine participation like l-alanine. In contrast, the structurally related D-galacturonic acid methyl ester showed less browning activity and degradation under equal reaction conditions. Pectin-specific degradation products such as 5-formyl-2-furanoic acid and 2-furanoic acid were found but could not be verified for d-galacturonic acid monomers alone.
authors.affiliation: Institute of Food Technology and Food Chemistry, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Wegener
authors.affiliation: Institute of Food Technology and Food Chemistry, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany.
authors.forename: Maria-Anna
authors.initials: MA
authors.lastname: Bornik
authors.affiliation: Institute of Food Technology and Food Chemistry, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany.
authors.forename: Lothar W
authors.initials: LW
authors.lastname: Kroh
mesh_terms: D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D006603:Hexuronic Acids / Q000737:chemistry*; D006358:Hot Temperature; D015416:Maillard Reaction; D010368:Pectins / Q000737:chemistry; D012996:Solutions; D014574:Uronic Acids / Q000737:chemistry; D014867:Water
chemical_list: D000596:Amino Acids; D006603:Hexuronic Acids; D012996:Solutions; D014574:Uronic Acids; D014867:Water; C007819:galacturonic acid; D010368:Pectins; D000409:Alanine
keywords: 3-hydroxypyridine; Maillard reaction; colored compounds; d-galacturonic acid; d-galacturonic acid methyl ester; d-glucuronic acid; l-alanine; nonenzymatic browning; pyrrole-2-carboxaldehyde