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Rheology, DSC and Volume or Weight Change Induced by Immersion in Solvents for Agarose and Kappa-Carrageenan Gels

1986; Springer Nature; Volume: 18; Issue: 12 Linguagem: Inglês

10.1295/polymj.18.1017

1349-0540

Mineo Watase, Katsuyoshi Nishinari,

Seaweed-derived Bioactive Compounds

In order to study the gelling ability of kappa-carrageenan and agarose, measurements of dynamic viscoelasticity, differential scanning calorimetry (DSC) and volume or weight change induced by immersion in organic solvents have been made at the range of concentration from 2 to 8% (w/w). The results obtained are as follows; (1) The value of dynamic Young's modulus E′ for agarose gels increases with increasing temperature up to about 35°C, while it decreases rapidly with increasing temperature above about 35°C. On the other hand, the value of E′ for kappa-carrageenan gels decreases with increasing temperature. (2) DSC curves show one endothermic peak which is caused by the melting of gels. The temperature of the endothermic peak accompanying the melting of agarose gels is independent of concentrations, and that of carrageenan gels shifts to higher temperatures with increasing concentrations. (3) The weight or volume change by immersion in dimethyl sulfoxide (DMSO)–water or in ethanol is far more remarkable in kappa-carrageenan gels than in agarose gels. The difference of these kinds of behaviour between agarose and kappa-carrageenan gels is understood mainly by the quantity and position of sulfate side groups in molecules.