Maillard compounds as crosslinks in heated beta-casein-glucose systems.

Summary Heat-induced covalent aggregation of β-casein reported to be sugar-dependent has been studied with respect to both the early and advanced stages of the Maillard reaction. The aggregation of β-casein via reaction with glucose evaluated by gel-permeation chromatography in model solutions heated under a wide range of concentrations appeared to occur free of interference only in very dilute solutions (1 mg protein/mL), and was not related to the amount of fructoselysine and lysyl pyrraline. It was clearly related to the formation of pentosidine which, however, never exceeded 2 mmol/mol β-casein. The heat-induced incorporation of [U-14C]-labelled Lys or Arg into β-casein in the presence of glucose simulated intermolecular crosslinking and suggested that only few reactive residues can act as acceptors. The radioactive patterns obtained by Ion-exchange chromatography and RP-HPLC. after either acid or enzymatic hydrolysis of the labelled β-casein, showed that highly basic and hydrophobic molecules involving mutual interactions of Arg and Lys are responsible for β-casein aggregation.