title: Antioxidant Properties of Aqueous Extract of Roasted Hulled Barley in Bulk Oil or Oil-in-Water Emulsion Matrix.
abstract: Antioxidant properties of the aqueous extracts of hulled barley (Hordeum vulgare L.) that had been roasted at 210 °C for 20 min were determined in bulk oil and oil-in-water (O/W) emulsions. Bulk oils were heated at 60, 100, and 180 °C, and O/W emulsions were oxidized under riboflavin photosensitization. The content of phenolic compounds was analyzed by high-performance liquid chromatography, and in vitro antioxidant assays were also conducted. The major phenolics contained in the aqueous extract of roasted hulled barley (AERB) were p-coumaric, ferulic, protocatechuic, chlorogenic, 4-hydroxybenzoic, and vanillic acids. Depending on the concentration and oxidation temperature, AERB had antioxidant or prooxidant properties in bulk oil. At 60 °C, AERB at a concentration of 0.5% acted as a prooxidant, whereas at 1.0% it acted as an antioxidant. At 100 °C, AERB acted as an antioxidant irrespective of concentration. In 180 °C conditions, 0.5% AERB acted as a prooxidant, whereas other concentrations of AERB acted as antioxidants. In the case of riboflavin photosensitized O/W emulsions, AERB showed antioxidant properties irrespective of concentration. Antioxidant abilities of AERB are affected by the food matrix, including bulk oil and O/W emulsions, and concentrations of AERB, even though diverse phenolic compounds may display high antioxidant properties in in vitro assays.
  
  
  CONCLUSIONS
  Roasted barley has been widely used as a tea ingredient in East Asian countries such as Korea, China, and Japan. The highly antioxidative properties of the aqueous extracts of roasted barley have been confirmed in bulk oil and O/W emulsions as well as in vitro assays because of the presence of phenolic compounds. The results of this study can contribute to the development of antioxidant-rich beverages using roasted barley by aiding in the selection of proper food matrix-containing extracts of high phenolic compounds, as well as by expanding consumers’ choices for healthy beverages.
authors.affiliation: Dept. of Food Science and Biotechnology, Sungkyunkwan Univ, Suwon, Korea.
authors.forename: Sumi
authors.initials: S
authors.lastname: Oh
authors.affiliation: Dept. of Food and Nutrition, Kangwon National University, Samcheok, Korea.
authors.forename: Mi-Ja
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Dept. of Food Science and Biotechnology, Sungkyunkwan Univ, Suwon, Korea.
authors.forename: Kye Won
authors.initials: KW
authors.lastname: Park
authors.affiliation: Dept. of Food Science and Biotechnology, Sungkyunkwan Univ, Suwon, Korea.
authors.forename: Jae Hwan
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000494:pharmacology*; D001628:Beverages; D002681:China; D003296:Cooking; D003314:Corn Oil / Q000378:metabolism*; D002523:Edible Grain / Q000737:chemistry; D004655:Emulsions; D001467:Hordeum / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D007564:Japan; D015227:Lipid Peroxidation; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D017382:Reactive Oxygen Species; D056910:Republic of Korea; D014867:Water / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D004655:Emulsions; D010636:Phenols; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D014867:Water; D003314:Corn Oil
keywords: antioxidant property; aqueous extract of hulled barley; bulk oil; oil-in-water emulsion; phenolic