INFLUENCE OF LOCUST BEAN GUM ON THE RHEOLOGICAL PROPERTIES OF KAPPA-CARRAGEENAN SYSTEMS IN THE VICINITY OF THE GEL POINT

Viscosity and oscillatory shear measurements have been performed on ka ppa-carrageenan alone and on kappa-carrageenan/galactomannan (guar gum or locust bean gum) blends in the vicinity of the sol-gel transition. From these measurements, a phase diagram showing the boundary limits for kappa-carrageenan/locust bean gum and kappa-carrageenan/guar gum w as established. The viscoelastic behaviour at the transition showed th at this process was sharp for the kappa-carrageenan/locust bean gum bl end, while for the kappa-carrageenan/guar gum blend, it was more progr essive. The kappa-carrageenan content at which the transition took pla ce was estimated and was found to be constant, whatever the total poly mer concentration of the mixture studied. This phase transition result s in a system whose theological properties are far removed from those of the original biopolymers. However, it is shown that kappa-carrageen an is primarily responsible for gel network formation.