title: Glycation Reactions of Casein Micelles.
abstract: After suspensions of micellar casein or nonmicellar sodium caseinate had been heated, respectively, in the presence and absence of glucose for 0-4 h at 100 °C, glycation compounds were quantitated. The formation of Amadori products as indicators for the "early" Maillard reaction were in the same range for both micellar and nonmicellar caseins, indicating that reactive amino acid side chains within the micelles are accessible for glucose in a comparable way as in nonmicellar casein. Significant differences, however, were observed concerning the formation of the advanced glycation end products (AGEs), namely, N(ε)-carboxymethyllysine (CML), pyrraline, pentosidine, and glyoxal-lysine dimer (GOLD). CML could be observerd in higher amounts in nonmicellar casein, whereas in the micelles the pyrraline formation was increased. Pentosidine and GOLD were formed in comparable amounts. Furthermore, the extent of protein cross-linking was significantly higher in the glycated casein micelles than in the nonmicellar casein samples. Dynamic light scattering and scanning electron microscopy showed that glycation has no influence on the size of the casein micelles, indicating that cross-linking occurs only in the interior of the micelles, but altered the surface morphology. Studies on glycation and nonenzymatic cross-linking can contribute to the understanding of the structure of casein micelles.
authors.affiliation: Department of Chemistry and Food Chemistry, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Moeckel
authors.affiliation: Department of Chemistry and Food Chemistry, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Duerasch
authors.affiliation: Department of Chemistry and Food Chemistry, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Weiz
authors.affiliation: Department of Chemistry and Food Chemistry, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Ruck
authors.affiliation: Department of Chemistry and Food Chemistry, Technische Universität Dresden , 01062 Dresden, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Henle
mesh_terms: D002364:Caseins / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D017127:Glycation End Products, Advanced / Q000737:chemistry; D006037:Glyoxal / Q000737:chemistry; D015416:Maillard Reaction; D008823:Micelles
chemical_list: D002364:Caseins; D017127:Glycation End Products, Advanced; D008823:Micelles; D006037:Glyoxal; D005947:Glucose
keywords: Maillard reaction; casein micelle; cross-link; glycation; scanning electron microscopy; sodium caseinate