Phospholipid oxidation and nonenzymatic browning development in phosphatidylethanolamine/ribose/lysine model systems

Fatty acid losses, lipid oxidation, pyrrole formation, and browning and fluorescence development were determined in four mixtures of phosphatidylethanolamine (PE), ribose (RI), and/or lysine (lys) incubated at 37 °C to study the influence of lipid oxidation on the Maillard reaction and vice versa. Under the conditions assayed, the amino group of PE was preferentially damaged compared with the amino group of lys. In addition, oxidized lipid/amino acid reactions produced more pyrrolization, browning and fluorescence than carbohydrate/amino acid reactions, but both oxidized lipid/amino acid and sugar/amino acid reactions were produced in the PE/RI/lys system and both of them were inhibited by the presence of the other. Thus, fewer RI/lys reaction products were produced in the PE/RI/lys system than in an analogous system with no PE added. All these results confirm that there is an interaction between lipid oxidation and the Maillard reaction, and both of them should be considered simultaneously to understand their consequences on foods when lipids, carbohydrates, and amino acids or proteins are present.