Effect of monovalent cations on calcium-induced assemblies of kappa carrageenan
| dc.contributor.author | Evageliou, Vasiliki I. | |
| dc.contributor.author | Ryan, Patricia M. | |
| dc.contributor.author | Morris, Edwin R. | |
| dc.date.accessioned | 2018-03-22T11:46:33Z | |
| dc.date.available | 2018-03-22T11:46:33Z | |
| dc.date.issued | 2018-03-09 | |
| dc.date.updated | 2018-03-22T11:40:47Z | |
| dc.description.abstract | The effect of Na+, K+ and Ca2+ cations on the thermal stability and aggregation of kappa carrageenan double helices has been explored by differential scanning calorimetry (DSC). Previous studies have shown that kappa carrageenan helices bind K+ cations, but not Na+. The kappa carrageenan used in this work was therefore in the Na+ salt form, to avoid complications from site-bound counterions to the polymer, and was studied at a fixed concentration of 1.0 wt % (∼25 mN w.r.t. sulfate groups). Na+, K+ and Ca2+ cations were added as chloride salts. Values of peak-maximum temperature (Tmax) in DSC cooling and heating scans (0.5 °C/min) increased progressively with increasing salt concentration, following the order Na+< Ca2+< K+, but greatest thermal hysteresis was seen with Ca2+. Our proposed interpretation is that Ca2+ cations "cement" the carrageenan helices together by binding directly between them, giving greater thermal stability, and thus greater hysteresis, than K+ cations which act indirectly by suppressing charge. On progressive addition of NaCl or KCl to solutions incorporating Ca2+ at concentrations of 5 mM or 12.5 mM (stoichiometric equivalence) the values of Tmax moved asymptotically towards those seen for the same concentrations of the monovalent cations in the absence of calcium, suggesting progressive displacement of site-bound Ca2+. Thus Tmax for the order–disorder transition was increased by KCl but reduced by NaCl, with the strange consequence that addition of NaCl lowered the transition temperature rather than raising it. | en |
| dc.description.status | Peer reviewed | en |
| dc.description.version | Accepted Version | en |
| dc.format.mimetype | application/pdf | en |
| dc.identifier.citation | Evageliou, V. I., Ryan, P. M. and Morris, E. R. (2018) 'Effect of monovalent cations on calcium-induced assemblies of kappa carrageenan', Food Hydrocolloids, In Press. doi:10.1016/j.foodhyd.2018.03.018 | en |
| dc.identifier.doi | 10.1016/j.foodhyd.2018.03.018 | |
| dc.identifier.endpage | 5 | en |
| dc.identifier.issn | 0268-005X | |
| dc.identifier.journaltitle | Food Hydrocolloids | en |
| dc.identifier.startpage | 1 | en |
| dc.identifier.uri | https://hdl.handle.net/10468/5677 | |
| dc.language.iso | en | en |
| dc.publisher | Elsevier | en |
| dc.relation.uri | http://www.sciencedirect.com/science/article/pii/S0268005X17316806 | |
| dc.rights | © 2018 Elsevier Ltd. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license. | en |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | en |
| dc.subject | Kappa carrageenan | en |
| dc.subject | Differential scanning calorimetry | en |
| dc.subject | Calcium ions | en |
| dc.subject | Cation binding | en |
| dc.title | Effect of monovalent cations on calcium-induced assemblies of kappa carrageenan | en |
| dc.type | Article (peer-reviewed) | en |
