TY - JOUR
T1 - Sol-gel transition temperatures of high acyl gellan with monovalent and divalent cations from rheological measurements
AU - Flores-Huicochea, Emmanuel
AU - Rodríguez-Hernández, Adriana I.
AU - Espinosa-Solares, Teodoro
AU - Tecante, Alberto
N1 - Funding Information:
We appreciate the financial support from CONACyT through grant CB-101497 . Financial support from Programa de Maestría y Doctorado en Ingeniería–UNAM is also appreciated. E.F.H. acknowledges COTEPABE-IPN for authorizing him to pursue doctorate research and CONACyT for partial financial support. Thanks are also given to Mariana Ramirez-Gilly for her technical support with rheological measurements.
PY - 2013/6
Y1 - 2013/6
N2 - The sol-gel transition temperatures of 0.1-1.0% high acyl gellan (HAG) with 0-200 mM NaCl or KCl and 0-20 mM CaCl2 or MgCl2 were determined using rheological measurements. Transition temperatures for monovalent cations, Na+ and K+, in the range of 50-80 °C were not significantly different (p > 0.5). Absence of thermal hysteresis was the salient feature. However, thermal hysteresis (∼4.4 °C) was observed for 0.1% HAG without added salt, but disappeared on increasing HAG and counterion concentrations. Few concentrations of HAG and added monovalent and divalent cations showed thermal hysteresis not higher than 2.5 °C. Transition temperatures for divalent cations were similar to those for monovalent cations although for considerably lower concentrations of Ca2+ or Mg2+. Increasing concentrations of monovalent and divalent counterions give rise to higher transition temperatures but not to higher storage moduli. This was interpreted as a lack of cross-link formation in the three-dimensional network structure of the gels. A single sol-gel transition diagram for monovalent cations is proposed, in which different zones associated with the presence of ordered and disordered conformations serve to identify the conditions in which HAG can exist in aqueous media.
AB - The sol-gel transition temperatures of 0.1-1.0% high acyl gellan (HAG) with 0-200 mM NaCl or KCl and 0-20 mM CaCl2 or MgCl2 were determined using rheological measurements. Transition temperatures for monovalent cations, Na+ and K+, in the range of 50-80 °C were not significantly different (p > 0.5). Absence of thermal hysteresis was the salient feature. However, thermal hysteresis (∼4.4 °C) was observed for 0.1% HAG without added salt, but disappeared on increasing HAG and counterion concentrations. Few concentrations of HAG and added monovalent and divalent cations showed thermal hysteresis not higher than 2.5 °C. Transition temperatures for divalent cations were similar to those for monovalent cations although for considerably lower concentrations of Ca2+ or Mg2+. Increasing concentrations of monovalent and divalent counterions give rise to higher transition temperatures but not to higher storage moduli. This was interpreted as a lack of cross-link formation in the three-dimensional network structure of the gels. A single sol-gel transition diagram for monovalent cations is proposed, in which different zones associated with the presence of ordered and disordered conformations serve to identify the conditions in which HAG can exist in aqueous media.
KW - Gellan
KW - Gels
KW - Polysaccharides
KW - Rheology
KW - Sol-gel transition
UR - http://www.scopus.com/inward/record.url?scp=84875111568&partnerID=8YFLogxK
U2 - 10.1016/j.foodhyd.2012.11.007
DO - 10.1016/j.foodhyd.2012.11.007
M3 - Artículo
AN - SCOPUS:84875111568
SN - 0268-005X
VL - 31
SP - 299
EP - 305
JO - Food Hydrocolloids
JF - Food Hydrocolloids
IS - 2
ER -