title: Antioxidant activities of rice bran protein hydrolysates in bulk oil and oil-in-water emulsion.
abstract: BACKGROUND
  Recently, utilization of natural antioxidants in food processing has been of growing interest, owing to the concerns of health hazards of synthetic agents. Protein hydrolysates are a potent candidate for this purpose. In this work, rice bran protein hydrolysates (RBPH) with various degrees of hydrolysis (DH) were prepared, and their antioxidant activities in soybean oil and oil-in-water (O/W) emulsion were examined.
  
  
  RESULTS
  With increasing DH, RBPH showed increasing antioxidant activities, as evidenced by the increases in DPPH radical scavenging activity, reducing power and ferrous chelating activity (P < 0.05). The improved activity was associated with increasing surface hydrophobicity (SoANS). After hydrolysis for 60 min, the content of hydrophobic amino acids was increased. When RBPH with various DH were incorporated into bulk soybean oil and O/W emulsion stored at 37 °C for up to 15 days, lipid oxidation was successfully retarded, especially when DH increased. The efficiency in prevention of oxidation was dose dependent (0-10 g L(-1)), as indicated by the lower peroxide value and thiobarbituric reactive substances.
  
  
  CONCLUSIONS
  The present work suggests that RBPH might be potently employed as a natural antioxidant in both bulk oil and emulsion models.
authors: Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.
authors: Nopparat
authors: N
authors: Cheetangdee
authors: Soottawat
authors: S
authors: Benjakul
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000378:metabolism; D004655:Emulsions; D005511:Food Handling / Q000379:methods; D005519:Food Preservation / Q000379:methods*; D006801:Humans; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D015227:Lipid Peroxidation; D012275:Oryza / Q000737:chemistry*; D010084:Oxidation-Reduction; D010851:Picrates / Q000378:metabolism; D010940:Plant Proteins / Q000494:pharmacology*; D011492:Protein Hydrolysates / Q000494:pharmacology*; D012639:Seeds / Q000737:chemistry; D013024:Soybean Oil / Q000378:metabolism*; D017392:Thiobarbituric Acid Reactive Substances
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D001713:Biphenyl Compounds; D004655:Emulsions; D010851:Picrates; D010940:Plant Proteins; D011492:Protein Hydrolysates; D017392:Thiobarbituric Acid Reactive Substances; D013024:Soybean Oil; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: antioxidant activity; bulk oil; oil-in-water emulsion; rice bran protein hydrolysates