title: Physicochemical properties of cassava starch oxidized by sodium hypochlorite.
abstract: In this work, cassava starch was modified by treatment with sodium hypochlorite (NaClO) at different concentrations (0.8, 2.0 and 5.0 % of active chlorine) and selected physicochemical properties of the oxidized starches were investigated. The native and modified samples were evaluated considering moisture, carboxyl content, apparent viscosity, susceptibility to syneresis, mid-infrared spectroscopy and crystallinity index. The treatment with NaClO resulted in alterations in carboxyl content of the oxidized starches that increased with increasing concentration of the oxidant. Oxidized starches also showed higher susceptibility to syneresis, as assessed by the release of liquid during freezing and thawing. Apparent viscosity analysis showed decrease in peak viscosity of the oxidized starches. X-ray diffractograms showed that the oxidation influenced the extent of cassava starch relative crystallinity found to lie between 34.4 % (native) and 39.9 % (2.0 % active chlorine). The infrared spectra are sensitive to structural changes on starch macromolecules and presented characteristic peaks as C-O-C of the six carbon glucose ring absorbs at 1,150-1,085 cm(-1) and due to axial deformation these bands changed with the crystal structure of the starch samples.
authors.affiliation: Food Science and Technology Department, Universidade Estadual de Ponta Grossa (UEPG), Avenida Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR Brazil.
authors.forename: Lúcia Helena
authors.initials: LH
authors.lastname: Garrido
authors.affiliation: Food Science and Technology Department, Universidade Estadual de Ponta Grossa (UEPG), Avenida Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR Brazil.
authors.forename: Egon
authors.initials: E
authors.lastname: Schnitzler
authors.affiliation: Food Science and Technology Department, Universidade Estadual de Ponta Grossa (UEPG), Avenida Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR Brazil.
authors.forename: Manoela Estefânea Boff
authors.initials: ME
authors.lastname: Zortéa
authors.affiliation: Food Science and Engineering Department, IBILCE/Unesp, Rua Cristóvão Colombo, 2265, 15054-000 São José do Rio Preto, SP Brazil.
authors.forename: Thaís
authors.initials: T
authors.lastname: de Souza Rocha
authors.affiliation: Food Science and Technology Department, Universidade Estadual de Ponta Grossa (UEPG), Avenida Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR Brazil.
authors.forename: Ivo Mottin
authors.initials: IM
authors.lastname: Demiate
keywords: Active chlorine; Apparent viscosity; Carboxyl content; Manihot esculenta; Oxidation