title: Structure, morphology and functionality of acetylated and oxidised barley starches.
abstract: Acetylation and oxidation are chemical modifications which alter the properties of starch. The degree of modification of acetylated and oxidized starches is dependent on the catalyst and active chlorine concentrations, respectively. The objective of this study was to evaluate the effect of acetylation and oxidation on the structural, morphological, physical-chemical, thermal and pasting properties of barley starch. Barley starches were acetylated at different catalyst levels (11%, 17%, and 23% of NaOH solution) and oxidized at different sodium hypochlorite concentrations (1.0%, 1.5%, and 2.0% of active chlorine). Fourier-transformed infrared spectroscopy (FTIR), X-ray diffractograms, thermal, morphological, and pasting properties, swelling power and solubility of starches were evaluated. The degree of substitution (DS) of the acetylated starches increased with the rise in catalyst concentration. The percentage of carbonyl (CO) and carboxyl (COOH) groups in oxidized starches also increased with the rise of active chlorine level. The presence of hydrophobic acetyl groups, carbonyl and carboxyl groups caused a partial disorganization and depolymerization of starch granules. The structural, morphological and functional changes in acetylated and oxidized starches varied according to reaction conditions. Acetylation makes barley starch more hydrophobic by the insertion of acetyl groups. Also the oxidation promotes low retrogradation and viscosity. All these characteristics are important for biodegradable film production.
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil. Electronic address: shanisemell@hotmail.com.
authors.forename: Shanise Lisie Mello
authors.initials: SL
authors.lastname: El Halal
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Rosana
authors.initials: R
authors.lastname: Colussi
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil; Department of Food Science, University of Guelph, Ontario N1G 2W1, Canada.
authors.forename: Vânia Zanella
authors.initials: VZ
authors.lastname: Pinto
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Josiane
authors.initials: J
authors.lastname: Bartz
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Marjana
authors.initials: M
authors.lastname: Radunz
authors.affiliation: Department of Electronic Microscopy, Course in the Engineering of Materials, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Neftali Lenin Villarreal
authors.initials: NL
authors.lastname: Carreño
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Alvaro Renato Guerra
authors.initials: AR
authors.lastname: Dias
authors.affiliation: Department of Science and Agro-Industrial Technology, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Elessandra da Rosa
authors.initials: Eda R
authors.lastname: Zavareze
mesh_terms: D000107:Acetylation; D001467:Hordeum / Q000737:chemistry*; D010084:Oxidation-Reduction; D017550:Spectroscopy, Fourier Transform Infrared; D013213:Starch / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D013213:Starch
keywords: Acetyl group; Acetylation; Barley starch; Carbonyl; Carboxyl; Oxidation