title: Synergistic effects of mixed salt on the gelation of κ-carrageenan.
abstract: The effect of the addition of calcium or sodium ions on the potassium induced gelation of κ-carrageenan (κ-car) is investigated using oscillatory shear rheology and turbidimetry. Both the gelation kinetics and the steady state shear moduli are investigated. Gelation in mixed salt solutions is compared with that in pure potassium and calcium solutions. It is shown that the elastic shear modulus increases with increasing pure KCl concentration, but decreases with increasing pure CaCl2 concentration. In mixed salts, gelation of κ-car is induced by potassium and addition of CaCl2 leads to an increase of the elastic modulus with increasing CaCl2 concentration. κ-Car gelled at low mixed salt concentrations for which it remained liquid in pure salt. At equivalent ionic strengths, the effect of adding NaCl on potassium induced gelation is much weaker. In pure KCl solutions, κ-car gels are transparent, but in pure CaCl2 they become increasingly turbid with increasing CaCl2 concentration. The turbidity of gels formed in mixed salts is intermediate.
authors.affiliation: LUNAM, Université du Maine, IMMM UMR CNRS 6283, PCI, 72085 Le Mans cedex 9, France.
authors.forename: Bach T
authors.initials: BT
authors.lastname: Nguyen
authors.affiliation: LUNAM, Université du Maine, IMMM UMR CNRS 6283, PCI, 72085 Le Mans cedex 9, France. Electronic address: Taco.Nicolai@univ-lemans.fr.
authors.forename: Taco
authors.initials: T
authors.lastname: Nicolai
authors.affiliation: LUNAM, Université du Maine, IMMM UMR CNRS 6283, PCI, 72085 Le Mans cedex 9, France.
authors.forename: Lazhar
authors.initials: L
authors.lastname: Benyahia
authors.affiliation: LUNAM, Université du Maine, IMMM UMR CNRS 6283, PCI, 72085 Le Mans cedex 9, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Chassenieux
mesh_terms: D002118:Calcium / Q000737:chemistry; D002122:Calcium Chloride / Q000737:chemistry*; D002351:Carrageenan / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D009994:Osmolar Concentration; D011188:Potassium / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry
chemical_list: D005782:Gels; D012965:Sodium Chloride; D011189:Potassium Chloride; D002351:Carrageenan; D012964:Sodium; D002122:Calcium Chloride; D011188:Potassium; D002118:Calcium
keywords: Carrageenan; Gel; Polysaccharide; Rheology; Turbidity