Determination of the partial specific volumes of thermoreversible gelatin/water and κ‐carrageenan/water gels

In this paper systematic density measurements of gelatin/water and κ‐carrageenan/water gels are presented in a wide range of concentrations and temperatures. From about 600 measurements for gelatin/water and about 500 measurements for the system κ‐carrageenan/water empirical relations for both systems have been derived which allow to calculate the densities of these gels in a limited concentration range if the temperatures and the polymer weight fractions are known. The calculated densities have an accuracy of better than 0,001 g/cm −3 compared with the directly measured densities. If the extrapolated partial specific volumes of the pure polymer are plotted against the temperature, a jump with an inflexion point can be detected at about 23–24°C for both systems. These data indicate a Λ‐type transition of the expansion coefficient α for both systems at 23–24°C although there are still too few data to make clear conclusions.