title: Preparation of antioxidant peptide from egg white protein and improvement of its activities assisted by high-intensity pulsed electric field.
abstract: BACKGROUND
  Egg white protein powder was hydrolyzed by three proteases-alcalase, trypsin, and pepsin-to produce antioxidant peptides. Three kinds of hydrolysates were prepared under optimal enzymatic parameters that were obtained from the preliminary one-factor-at-a-time test and response surface methodology. Thereafter, three enzymatic hydrolysates were sequentially fractionated by ultrafiltration membranes in cut-off MW of 30, 10, and 1 kDa, and tested in terms of their reducing power (RP). Effects of high-intensity pulsed electric field (PEF) were further investigated on the antioxidant peptides to improve their activities.
  
  
  RESULTS
  Alcalase hydrolysates possessed stronger RP ability than the other two hydrolysates, particularly for the fraction within < 1 kDa. After PEF treatment, this fraction showed an improvement of RP ability within 4 h; however, the effects were reversible. High-performance liquid chromatographic analysis showed some MW changes of PEF-treated sample compared with control.
  
  
  CONCLUSIONS
  Among the three kinds of proteases, alcalase could be regarded as the most appropriate enzyme for preparation of bioactive peptide from egg white protein, with the best antioxidant activity. Also, PEF showed some effects on the peptide and could be further applied to improve its antioxidant activity.
authors.affiliation: Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, PR China.
authors.forename: Songyi
authors.initials: S
authors.lastname: Lin
authors.forename: Yang
authors.initials: Y
authors.lastname: Guo
authors.forename: Qi
authors.initials: Q
authors.lastname: You
authors.forename: Yongguang
authors.initials: Y
authors.lastname: Yin
authors.forename: Jingbo
authors.initials: J
authors.lastname: Liu
mesh_terms: D000975:Antioxidants / Q000378:metabolism* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004527:Egg Proteins / Q000378:metabolism*; D004529:Egg White / Q000737:chemistry; D004560:Electricity; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010434:Pepsin A / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism* / Q000494:pharmacology; D011492:Protein Hydrolysates / Q000096:biosynthesis* / Q000494:pharmacology; D013381:Subtilisins / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004527:Egg Proteins; D010455:Peptides; D011492:Protein Hydrolysates; D010447:Peptide Hydrolases; D013381:Subtilisins; D014357:Trypsin; D010434:Pepsin A