title: Small-angle X-ray scattering study on pectin-chitosan mixed solutions and thermoreversible gels.
abstract: Hot solutions containing pectin and chitosan with pectin weight fraction of 0.75, in acidic pH, demonstrate gelation occurring upon cooling to room temperature. This study explores the origin of this gelation using small angle X-ray scattering (SAXS) as the main experimental tool. Modeling SAXS patterns revealed rigid rod conformation in chitosan solutions, whereas pectin formed a self-avoiding chain. In addition, nanometric aggregates were detected in pectin solutions. Pectin and chitosan in mixed solutions adopted a similar semiflexible conformation. The only sample that created a visually stable gel displayed a different pattern, characteristic to polymers gels. Manipulating the composition by adding urea and salts highlighted the important role of hydrogen bonding, which governs the gelation mechanism. Nevertheless, electrostatic interactions were also found to take part in the gelation. To the best of our knowledge, this is the first comprehensive and systematic SAXS study on these pectin-chitosan mixtures.
authors.affiliation: Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
authors.forename: Irit
authors.initials: I
authors.lastname: Ventura
authors.affiliation: Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa, 32000, Israel. Electronic address: bianco@tx.technion.ac.il.
authors.forename: Havazelet
authors.initials: H
authors.lastname: Bianco-Peled
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D005782:Gels; D006860:Hydrogen Bonding; D049329:Nanostructures / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry*; D053838:Scattering, Small Angle; D014783:Viscosity
chemical_list: D005782:Gels; D010368:Pectins; D048271:Chitosan
keywords: Chitosan; Pectin; Polysaccharides mixtures; SAXS; Thermoreversible gel