The rheological properties of carrageenan gels (0.8-1.2 g/100 ml) were investigated in comparing the texture parameters, the rupture properties, the static and dynamic viscoelasticities with those of agar-agar gels. Sulfur content, intrinsic viscosity [η], melting point and transmissivity of gels were also measured so as to obtain correlation of the rheological properties.
Both carrageenan and agar-agar are polysaccharide which are extracted from Red Alagae. Although, those two kinds of hydrogels were found to be quite different in the rheological properties. The dynamic mudulus (
E') and the rupture stress (
Pf) of carrageenan gels were smaller than those of agar-agar gels. Intrinsic viscosity [η] and sulfur content of carrageenan were greater than those of agar-agar. It is noted the greater sulfur content of the sample, the smaller
E',
Pf and melting point of gel, although the relationship between the rheological properties and [η] was not clear. In a range of temperature from 10 to 50 °C,
E' of agar-agar gel was almost constant. On the contrary,
E' of carrageenan gels decreased rapidly between 30 and 40 °C.
Carrageenan was found to be adequate gelling agent for jelly because of the suitable cohesiveness, softness and transparence of this gel.
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