Utilization of dynamic oscillatory measurements for agar threshold gel concentration and gel strength determination

In this paper the development of a method for theological determination of threshold gel concentration and quantification of gel strength of agar is shown. The threshold gel concentration was determined by performing frequency sweep tests at different agar concentrations (0.05%, 0.1%, 0.15%, etc.). The values of threshold gel concentration (concentration after which crossover between storage and loss modulus was observed) were not higher than 0.25%. Gel strength was expressed as the value of the storage modulus (G'). The results obtained using frequency sweep tests were in a good agreement with the results obtained by standard test for threshold gel concentration determination and the results of gel strength measured by Texture Analyzer. Therefore, it can be concluded that dynamic oscillatory measurements can successfully replace other tests for agar characterization. The special advantage of this test is that in one test it is possible to obtain the results of different parameters such as threshold gel concentration, gel strength and viscoelastic properties of agar.