Covalent protein adduct formation and protein cross-linking resulting from the maillard reaction between cyclotene and a model food protein.

Covalent Maillard products of the reactions of carbonyl compounds with proteins are often described in the literature, but, until recently, evidence for their existence has been indirect. Cyclotene (2-hydroxy-3-methylcyclopent-2-enone), a common flavor compound, was incubated with a model food protein, ribonuclease, and found to cross-link the protein. Size exclusion high-performance liquid chromatrography and electrospray mass spectrometry of the early stages of the reaction provide strong evidence for covalent adducts that we believe to be intermediates in the cross-linking reaction.