Measurement of the Rheology of Polysaccharide Gels by Penetration

The influence of penetration depth, probe radius and gel depth on the shear modulus calculated from penetration by the method of was determined for alginate, carrageenan and gelatin gels. For all three gels it was found the calculated modulus was independent of penetration distance at low distances (<5 mm) and independent of gel depth provided this was not small. For the polysaccharide gels, however, the calculated modulus depended on probe radius whereas for gelatin gels it was radius independent. This suggested that, in contrast to gelatin, the use of this approach to obtain fundamental moduli for alginate and carrageenan gels from penetration experiments at forces measurable with commercially available Texture Analysers is invalid.