Effects of Cation Properties on Sol‐gel Transition and Gel Properties of κ‐carrageenan

Abstract

The phase transition temperatures, rheological properties and gel-network characteristics for gelation of -carrageenan-salt (NaCl, KCl and CaCl 2 ) solutions and their aged gels were investigated. The effectiveness of increasing gelling and gel-melting temperatures at the salt concentrations examined followed the sequence of K + > Ca 2+ > Na + . This sequence was also true for the gel strength and the melting enthalpy (DH) of the most crosslinked junction zones of aged gels at low salt concentrations. Nonetheless, a different order (Ca ++ > K + and Na + ) was found for increasing storage modulus and gelation rate during early-stage gelation, thermal hysteresis and the DH of aged gels in some salt-carrageenan systems.

Gelation behaviour of aqueous solutions of different types of carrageenan investigated by low-intensity-ultrasound measurements and comparison to rheological measurements

“…12 and 13) because K + compensates the negative charges of the carrageenan molecules and promotes their ability to form double helices and respective aggregates. The effect of K + on the gelation of n-carrageenan was confirmed in many investigations (Lai, Wong & Lii, 2000;Morris et al, 1980;Takemasa, Chiba, & Date, 2001). Similarly, as mentioned above, T m , T g and (T m -T g ) of n-carrageenan from the ultrasonic measurement are lower than those determined by the rheological measurement (Fig.…”

Carrageenan: a review

“…Carrageenans, as linear, water-soluble, polymers, typically form highly viscous aqueous solutions. Viscosity depends on concentration, temperature, the presence of other solutes, and the type of carrageenan and its molecular weight (Lai et al 2000). Viscosity increases nearly exponentially with concentration and decreases with temperature.…”

Sorption and Desorption of PVA-Pyrene Chains in and out of Agarose Gel

“…At higher temperatures (>60°C), a structural destruction occurs due to breaking of molecular bonds, and gel-sol transition takes place [5,7,10,11]. Agarose and carrageenan gel systems show a strong hysteresis behavior on these thermal transitions [5,[12][13][14]. X-ray diffraction [5,15], light scattering [15,16], fluorescence correlation spectroscopy (FCS) [17], optical rotation [7,16], differential scanning calorimeter (DSC) [18], small-angle neutron scattering (SANS) [17,19,20], and dynamic viscoelastic measurements [18,21] are the some major techniques used in the inspection of the agarose gels.…”