title: Rheological characterization of acid pectin samples in the absence and presence of monovalent ions.
abstract: Pectins are traditionally divided into two groups, high methoxy and low methoxy. The groupings determine the charge of the pectin and the gelation mechanism. However, not as yet extensively studied is the impact on gelation of the distribution of the charges as characterized by an absolute degree of blockiness (DBabs). The aim of this study was to characterize rheologically the acid gelation of a pectin with a high DBabs and a degree of methyl esterification of ∼ 37%, in the absence and presence of monovalent ions. The results obtained suggest that a pectin with a blocky charge distribution at pH conditions close to or below the pKa exhibits weak gel-like properties at intermediate frequencies, despite the absence of a permanent network structure. The addition of monovalent ions changed the rheological behavior to resemble that of a strong gel whose properties depended on the type and concentration of the ions.
authors.affiliation: Applied Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden; SuMo BIOMATERIALS, VINN Excellence Center, Chalmers University of Technology, 412 96 Göteborg, Sweden. Electronic address: anna.strom@chalmers.se.
authors.forename: Anna
authors.initials: A
authors.lastname: Ström
authors.affiliation: Department of Structure and Material Design, The Swedish Institute for Food and Biotechnology, SIK, Göteborg, Sweden.
authors.forename: Erich
authors.initials: E
authors.lastname: Schuster
authors.affiliation: Singapore Institute of Technology, 10 Dover Drive, Singapore 138683, Singapore.
authors.forename: Suk Meng
authors.initials: SM
authors.lastname: Goh
mesh_terms: D007477:Ions; D010368:Pectins / Q000737:chemistry*; D012212:Rheology / Q000379:methods*; D012965:Sodium Chloride / Q000737:chemistry*
chemical_list: D007477:Ions; D012965:Sodium Chloride; D010368:Pectins
keywords: Acid gelation; Blocky pectin; Entangled solution; Fine structure; Random pectin; Weak gels