title: Antioxidative activity of protein hydrolysates prepared from alkaline-aided channel catfish protein isolates.
abstract: Antioxidative activity of hydrolyzed protein prepared from alkali-solubilized catfish protein isolates was studied. The isolates were hydrolyzed to 5, 15, and 30% degree of hydrolysis using the protease enzyme, Protamex. Hydrolyzed protein was separated into hydrolysates and soluble supernatants, and both of these fractions were studied for their metal chelating ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and their ability to inhibit the formation of thiobarbituric acid reactive substances (TBARS) in washed tilapia muscle containing tilapia hemolysate. Both hydrolysates and supernatants were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results showed that DPPH radical scavenging ability and reducing power of catfish protein hydrolysates decreased, whereas the ORAC value, metal chelating ability, and ability to inhibit TBARS increased, with an increase in the degree of hydrolysis. Hydrolysate samples showed higher DPPH radical scavenging ability and Fe(3+) reducing ability, and supernatant samples had higher metal chelating ability. In general, low molecular weight (MW) peptides had high ORAC values and high metal chelating ability, and high MW peptides had a higher reducing power (FRAP) and were more effective in scavenging DPPH radicals. In a washed muscle model system, the ability of catfish protein hydrolysates and their corresponding supernatants to inhibit the formation of TBARS increased with an increase in the degree of hydrolysis.
authors.affiliation: Laboratory of Aquatic Food Biomolecular Research, Aquatic Food Products Program, Department of Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Ann E
authors.initials: AE
authors.lastname: Theodore
authors.forename: Sivakumar
authors.initials: S
authors.lastname: Raghavan
authors.forename: Hordur G
authors.initials: HG
authors.lastname: Kristinsson
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001713:Biphenyl Compounds; D002614:Chelating Agents / Q000737:chemistry; D029941:Fish Proteins / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007059:Ictaluridae; D015227:Lipid Peroxidation / Q000187:drug effects; D009132:Muscles / Q000737:chemistry; D010851:Picrates; D017382:Reactive Oxygen Species / Q000737:chemistry; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D017210:Tilapia
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D002614:Chelating Agents; D029941:Fish Proteins; D010851:Picrates; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; C004931:1,1-diphenyl-2-picrylhydrazyl