title: Novel DNPH-based method for determination of protein carbonylation in muscle and meat.
abstract: Protein oxidation is considered an ongoing deteriorative process during storage of fresh and processed meat. Carbonyl compounds have traditionally been detected spectrophotometrically after derivatization with 2,4-dinitrophenylhydrazine (DNPH) to form protein-bound hydrazones with absorbance at 370 nm. Here we describe a novel DNPH-based method to quantify protein carbonylation in muscle and meat. The additional steps of the novel method aimed at increasing the protein solubility and inducing protein unfolding before labeling with DNPH. Compared to the traditional method, the new procedure reflected an increased protein carbonylation level measuring overall two to fourfold more carbonyls in muscles from different species as well as in soluble, salt-soluble and insoluble protein fractions. The study suggested that protein unfolding is a more important phenomenon than solubilization for increased DNPH labeling. The novel method resulted in three to fourfold larger carbonyl content determined in chicken, pork and beef (2.8, 3.6 and 3.1 nmol/mg of protein, respectively).
authors.affiliation: Department of Agricultural and Food Sciences, University of Bologna, 47521 Cesena, Italy; Department of Food and Environmental Sciences, FI-00014 University of Helsinki, Helsinki, Finland.
authors.forename: Francesca
authors.initials: F
authors.lastname: Soglia
authors.affiliation: Department of Agricultural and Food Sciences, University of Bologna, 47521 Cesena, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Petracci
authors.affiliation: Department of Food and Environmental Sciences, FI-00014 University of Helsinki, Helsinki, Finland. Electronic address: per.ertbjerg@helsinki.fi.
authors.forename: Per
authors.initials: P
authors.lastname: Ertbjerg
mesh_terms: D000818:Animals; D002417:Cattle; D002645:Chickens; D004044:Dietary Proteins / Q000737:chemistry; D005504:Food Analysis; D005511:Food Handling; D006834:Hydrazines / Q000032:analysis*; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000737:chemistry*; D050050:Protein Carbonylation; D013053:Spectrophotometry; D013552:Swine
chemical_list: D004044:Dietary Proteins; D006834:Hydrazines; C446799:dinitrophenylhydrazine
keywords: Protein carbonyls; Protein cross-linking; Protein oxidation; Protein solubility