Study of the compatibility/incompatibility of gelatin/iota-carrageenan/water mixtures

The incompatibility of acid gelatin/iota-carrageenan mixtures has been studied. Both these biopolymers undergo a conformational coil-helix transition under suitable conditions of temperature and salt. The aim of this work was to study the concentration at which mixtures are incompatible and the influence of pH, salt and temperature on the phase diagram. Incompatibility occurred over a wide range of concentrations for mixtures prepared in deionized water. Compatibility was increased by increasing the pH or the salt concentration. Temperature did not greatly influence the size of the incompatible region. This is in agreement with the hypothesis that attractive electrostatic interactions lead to associative phase separation (traditionally called complex coacervation).