title: Model Studies on the Antioxidative Effect of Polyphenols in Thermally Treated D-Glucose/L-Alanine Solutions with Added Metal Ions.
abstract: The influence of different polyphenolic compounds (PPs) on the Maillard reaction in a d-glucose/l-alanine model system with or without metal ions was studied under various reaction conditions. At temperatures up to 100 °C the PPs showed pro-oxidative effects due to their reducing effects on metal ions. This can be explained by a combined redox cycling mechanism of metals and PPs that promotes oxidation in the Maillard reaction. The antioxidative capacities of the PPs were measured with three different assays and correlated directly with their pro-oxidative effects on d-glucosone formation. The degree of the pro-oxidative effect depended not only on the PPs' reducing potential and their antioxidative ability but also on their concentration, the temperature, and the pH value of the model system. At low pH values and temperatures, the PPs were more stable and therefore showed an increased pro-oxidative tendency. In contrast, some of the used PPs were almost completely degraded at temperatures of 130 °C, and the formed polymers were able to complex metal ions. In the absence of these catalyzing ions, the oxidation ratio of d-glucose to d-glucosone was decreased.
authors.affiliation: Department of Food Chemistry and Food Analysis, Berlin Institute of Technology , Gustav-Meyer-Allee 25, TIB 4/3-1, D-13355 Berlin, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wilker
authors.affiliation: Department of Food Chemistry and Food Analysis, Berlin Institute of Technology , Gustav-Meyer-Allee 25, TIB 4/3-1, D-13355 Berlin, Germany.
authors.forename: Anna B
authors.initials: AB
authors.lastname: Heinrich
authors.affiliation: Department of Food Chemistry and Food Analysis, Berlin Institute of Technology , Gustav-Meyer-Allee 25, TIB 4/3-1, D-13355 Berlin, Germany.
authors.forename: Lothar W
authors.initials: LW
authors.lastname: Kroh
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000975:Antioxidants / Q000494:pharmacology*; D005511:Food Handling / Q000379:methods; D005947:Glucose / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D015416:Maillard Reaction / Q000187:drug effects; D008670:Metals / Q000737:chemistry*; D010084:Oxidation-Reduction; D059808:Polyphenols / Q000494:pharmacology*; D012996:Solutions / Q000737:chemistry
chemical_list: D000975:Antioxidants; D008670:Metals; D059808:Polyphenols; D012996:Solutions; D005947:Glucose; D000409:Alanine
keywords: Maillard reaction; antioxidative influence; d-glucosone; oxidation; polyphenol; pro-oxidative influence