title: Chemical and rheological characterization of the carrageenans from Hypnea musciformis (Wulfen) Lamoroux.
abstract: This work reports a chemical and rheological study of the carrageenans from Hypnea musciformis, a red seaweed commercially known for its production of κ-carrageenan. The polysaccharides were extracted with water both at room temperature and at 90 °C: the yield of the latter was about six times larger than the former. Fractionation with KCl yielded a large proportion (50-67%) of a precipitate with 0.125 M of this salt for both extracts, with characteristics of a nearly pure κ-carrageenan, as determined by methylation analysis and NMR spectroscopy. Smaller amounts of fractions precipitating at higher concentrations showed a basic κ-carrageenan structure, but included some ι-carrageenan diads. The KCl-soluble polysaccharides showed a larger complexity, containing d- and l-galactans or d/l-hybrids. Some differences in the rheological properties of these carrageenans have been found. Although all KCl-precipitating polysaccharides form true gels at 10 °C in presence of KCl, those extracted with hot water form stronger gels than those extracted at room temperature. Both purified κ-carrageenans show lower gelling and melting temperature than the whole polysaccharides from which they were originated.
authors: Departamento de Química Orgánica-CIHIDECAR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors: Vanina A
authors: VA
authors: Cosenza
authors: Departamento de Química Orgánica-CIHIDECAR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors: Diego A
authors: DA
authors: Navarro
authors: Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors: Eliana N
authors: EN
authors: Fissore
authors: Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
authors: Ana M
authors: AM
authors: Rojas
authors: Departamento de Química Orgánica-CIHIDECAR, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina. Electronic address: stortz@qo.fcen.uba.ar.
authors: Carlos A
authors: CA
authors: Stortz
mesh_terms: D002351:Carrageenan / Q000737:chemistry* / Q000302:isolation & purification; D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D012212:Rheology; D000461:Rhodophyta / Q000737:chemistry*
chemical_list: D002351:Carrageenan
keywords: Carrageenans; Dynamic oscillatory; Rheology; κ-Carrageenan