title: Lipid-oxidation-induced carboxymyoglobin oxidation.
abstract: We evaluated the usefulness of the ratio A503/A581 as a browning index (BI) for estimating brown color formation in solutions containing oxymyoglobin (OxyMb) and carboxymyoglobin (COMb). In split-chamber cuvette analyses with different proportions of metmyoglobin (MetMb), COMb and OxyMb, BI was highly correlated (r = 0.93-0.94) with direct estimation of MetMb. Moreover, A503/A581 was not influenced by different COMb-OxyMb proportions. Second, we investigated 4-hydroxy-2-nonenal (HNE)-induced spectral changes in OxyMb and COMb solutions. At pH 7.4 and 37 degrees C, BI was greater in HNE-treated OxyMb and COMb samples than in aldehyde-free controls (P < 0.05). However, at pH 5.6 and 4 degrees C, HNE-induced browning was more pronounced in COMb than in OxyMb. These results indicated that COMb is susceptible to lipid-oxidation-induced browning in a pH- and temperature-dependent manner.
authors.affiliation: Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40546, USA.
authors.forename: Surendranath P
authors.initials: SP
authors.lastname: Suman
authors.forename: Richard A
authors.initials: RA
authors.lastname: Mancini
authors.forename: Cameron
authors.initials: C
authors.lastname: Faustman
mesh_terms: D000818:Animals; D003116:Color; D006736:Horses; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation; D009211:Myoglobin / Q000737:chemistry*; D010084:Oxidation-Reduction; D013696:Temperature
chemical_list: D009211:Myoglobin; C018013:carboxymyoglobin; C017595:oxymyoglobin