Comparative antioxidant activity of Maillard- and oxidized lipid-damaged bovine serum albumin

The antioxidative activity of nonenzymatically browned proteins produced by reaction with both carbohydrates and oxidized lipids was studied to compare the effect of formation of Maillard reaction products (MRP) and oxidized lipid/amino acid reaction products (OLAARP) in the stabilities of foods during processing and storage. Bovine serum albumin (BSA) was incubated at 80 degrees C for 24 h in the absence (control, CO) or in the presence of 10 mM glucose (GL), fructose (FR), ribose (RI), methyl linoleate hydroperoxides (KP), and secondary products produced in the oxidation of methyl linoleate (SP). The modified proteins (COBSA, GLBSA, FRBSA, RIBSA, HPBSA, and SPBSB) were isolated, characterized by amino acid analysis, and tested for antioxidative activity (at 100 ppm) in soybean oil using the thiobarbituric acid-reactive substances (TEARS) assay. All of them significantly (p<0.05) decreased TEARS formation and exhibited the following order of effectiveness: COBSA < GLBSA < FRBSA approximate to HPBSA < SPBSA < RIBSA < BHT. No big differences among antioxidative properties of OLAARP- and MRP-containing proteins were observed under the assayed conditions. Therefore, both Maillard and oxidized lipid/protein reactions may be contributing analogously to increase the stability of foods during processing and storage.