title: In vitro antioxidant activity of rice protein affected by alkaline degree and gastrointestinal protease digestion.
abstract: BACKGROUND
  To elucidate whether and how alkali treatment, which is a common process for rice protein (RP) extraction, affects antioxidant activity of RP, the different degree of alkali (from 0.1% to 0.4% of NaOH) was used to extract RP (RP-1, RP-2, RP-3, RP-4).
  
  
  RESULTS
  The antioxidant capacities of scavenging free radicals [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid] diammonium salt, ABTS; 1,1-diphenyl-2-picrylhydrazyl, DPPH), chelating metals (iron, copper) and reducing power investigated in the hydrolysates of RPs (RP-1, RP-2, RP-3, RP-4) during in vitro pepsin-pancreatin digestion were effectively affected by alkali treatment. The present study demonstrated that the weakest antioxidant responses to ABTS radical-scavenging activity, DPPH radical-scavenging activity, iron chelating activity, copper chelating activity and reducing power were produced by RP-4 extracted by the highest alkali proportion (0.4% NaOH).
  
  
  CONCLUSIONS
  The present study indicates that antioxidant capacity of RP could be more readily depressed by strict alkali degree and affected by gastrointestinal proteases. Results suggest that alkali extraction is a vital process to regulate the antioxidant activity of RP through modifying the compositions of amino acids, which are dependent on alkali magnitude. © 2016 Society of Chemical Industry.
authors.affiliation: Department of Food Science and Engineering, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Food Science and Engineering, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China.
authors.forename: Zhengxuan
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Food Science and Engineering, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Food Science and Engineering, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China.
authors.forename: Mingcai
authors.initials: M
authors.lastname: Liang
authors.affiliation: Department of Food Science and Engineering, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 73 Huanghe Road, Harbin, 150090, China. ly6617@hit.edu.cn.
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000975:Antioxidants; D002614:Chelating Agents; D003300:Copper / Q000737:chemistry; D016166:Free Radical Scavengers; D041981:Gastrointestinal Tract / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007502:Iron Chelating Agents; D012275:Oryza / Q000737:chemistry*; D010194:Pancreatin / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D012639:Seeds / Q000737:chemistry
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D002614:Chelating Agents; D016166:Free Radical Scavengers; D007502:Iron Chelating Agents; D010940:Plant Proteins; D003300:Copper; D010194:Pancreatin; D010447:Peptide Hydrolases; D010434:Pepsin A
keywords: alkaline degree; antioxidant activity; in vitro digestion; rice protein