title: The revisited levels of free and bound phenolics in rice: Effects of the extraction procedure.
abstract: The effects of the type of solvolytic solution and number of extraction steps on the recovery of free phenolics, anthocyanins and proanthocyanidins from different rice samples were evaluated. Moreover, bound phenolic acids were determined as a function of enzymatic and/or alkaline hydrolysis treatment of the rice residue obtained after the extraction of free phenolics. The Acetone/Water (70:30 v/v) was the most effective solvolytic solution for extracting free phenolics from pigmented rice, as well as anthocyanins from black and wild rice, and proanthocyanidins from red rice. The application of three extraction steps increased the recovery of free phenolics up to 10%. The adoption of an enzymatic treatment, with α-amylase in order to reduce the paste viscosity of the residue, increased the extractability of bound phenolics. α-Amylase at 37°C during 15min followed by an alkaline hydrolysis at 37°C was the best treatment for the recovery of bound phenolics.
authors.affiliation: Department of Agroindustrial Science and Technology, Federal University of Pelotas, 96010-900 Pelotas, RS, Brazil.
authors.forename: Gabriela Hörnke
authors.initials: GH
authors.lastname: Alves
authors.affiliation: Department of Agroindustrial Science and Technology, Federal University of Pelotas, 96010-900 Pelotas, RS, Brazil.
authors.forename: Cristiano Dietrich
authors.initials: CD
authors.lastname: Ferreira
authors.affiliation: Department of Agroindustrial Science and Technology, Federal University of Pelotas, 96010-900 Pelotas, RS, Brazil.
authors.forename: Patrícia Gomes
authors.initials: PG
authors.lastname: Vivian
authors.affiliation: Instituto Federal de Educação, Ciência e Tecnologia Sul-Riograndense - Campus Pelotas, 96015-360 Pelotas, RS, Brazil.
authors.forename: Jander Luis Fernandes
authors.initials: JL
authors.lastname: Monks
authors.affiliation: Department of Agroindustrial Science and Technology, Federal University of Pelotas, 96010-900 Pelotas, RS, Brazil.
authors.forename: Moacir Cardoso
authors.initials: MC
authors.lastname: Elias
authors.affiliation: Department of Agroindustrial Science and Technology, Federal University of Pelotas, 96010-900 Pelotas, RS, Brazil.
authors.forename: Nathan Levien
authors.initials: NL
authors.lastname: Vanier
authors.affiliation: Department of Agroindustrial Science and Technology, Federal University of Pelotas, 96010-900 Pelotas, RS, Brazil. Electronic address: mauricio@labgraos.com.br.
authors.forename: Maurício
authors.initials: M
authors.lastname: de Oliveira
mesh_terms: D000872:Anthocyanins / Q000032:analysis; D006868:Hydrolysis; D062385:Hydroxybenzoates / Q000032:analysis*; D012275:Oryza / Q000737:chemistry*; D010636:Phenols / Q000032:analysis*; D010936:Plant Extracts / Q000737:chemistry*; D044945:Proanthocyanidins / Q000032:analysis
chemical_list: D000872:Anthocyanins; D062385:Hydroxybenzoates; D010636:Phenols; D010936:Plant Extracts; D044945:Proanthocyanidins; C017616:phenolic acid
keywords: Bound phenolics; Extraction of phenolics; Free phenolics; Phenolic acids; Pigmented rice