Concentration dependence of the properties of gelatin and iota-carrageenan systems at the gel point

Iota-carrageenan and gelatin gel properties are studied through the evolution of the frequency dependence of the storage and the loss moduli during gelation or melting near the critical point at several concentrations. The linear viscoelastic properties at the percolation threshold follow a power law [math]. The critical point is characterized by tan δ = G"/G' = tan(Δ.π/2) independently of the frequency and it may be precisely located using the variation at several frequencies of tan 5 versus any parameter controlling the advancement of gelation or melting (time, temperature or concentration). The effect of concentration has been studied and state diagrams [T = f(C)] are drawn for both biopolymers. A detailed study of Δ versus polymer concentration is carried out: values of in the range 0.72 - 0.36 are obtained and they are compared to published results and discusse