title: Antioxidative and prooxidative effects in food lipids and synergism with α-tocopherol of açaí seed extracts and grape rachis extracts.
abstract: Extracts of açaí seed and of grape rachis alone or in combination with α-tocopherol were evaluated as antioxidants in (i) bulk soybean oil, (ii) soybean oil liposomes and (iii) soybean-oil/water emulsions. The extracts made with 57% aqueous ethanol showed an antioxidant activity not dependent on concentration for grape rachis extracts and a concentration-dependent prooxidative activity for açaí seed extracts in bulk soybean oil. Both the extracts, however, protected liposome suspensions and oil/water emulsions against lipid oxidation. Synergism was demonstrated when extracts were combined with α-tocopherol, effects explained by the solubility of extract components in the water-phase and of α-tocopherol in the lipid-phase. Phenolic profiling of the extracts by U-HPLC-ESI-LTQ-MS was used to identify active antioxidants. Açaí seed and grape rachis extracts served as good sources of procyanidins and flavan-3-ols, imparted high antioxidant activity especially when combined with α-tocopherol and are suggested for protection of food oil/water emulsions.
authors.affiliation: Department of Agri-food Industry, Food and Nutrition, 'Luiz de Queiroz' College of Agriculture, University of São Paulo, Pádua Dias Avenue, P.O. Box 9, 13418-900 Piracicaba, SP, Brazil.
authors.forename: Priscilla Siqueira
authors.initials: PS
authors.lastname: Melo
authors.affiliation: São Carlos Institute of Chemistry, University of São Paulo, Trabalhador São Carlense Avenue 400, P.O. Box 780, 13560-970 São Carlos, SP, Brazil.
authors.forename: Leandro de Oliveira Rodrigues
authors.initials: LOR
authors.lastname: Arrivetti
authors.affiliation: Department of Agri-food Industry, Food and Nutrition, 'Luiz de Queiroz' College of Agriculture, University of São Paulo, Pádua Dias Avenue, P.O. Box 9, 13418-900 Piracicaba, SP, Brazil.
authors.forename: Severino Matias de
authors.initials: SM
authors.lastname: Alencar
authors.affiliation: Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C, Denmark. Electronic address: ls@food.ku.dk.
authors.forename: Leif H
authors.initials: LH
authors.lastname: Skibsted
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000378:metabolism; D065748:Euterpe; D056604:Grape Seed Extract / Q000032:analysis* / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000032:analysis / Q000378:metabolism; D012639:Seeds / Q000737:chemistry; D013024:Soybean Oil / Q000032:analysis / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods; D027843:Vitis; D024502:alpha-Tocopherol / Q000032:analysis* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D056604:Grape Seed Extract; D016877:Oxidants; D010936:Plant Extracts; D013024:Soybean Oil; D024502:alpha-Tocopherol
keywords: Antioxidant activity; Antioxidant synergism; Euterpe oleracea; Lipid peroxidation; Phenolic compounds; Vitis vinifera