Rheological characterisation of κ-carrageenan/locust bean gum mixtures

Abstract The rheological behaviour of the binary system of κ-carrageenan and locust bean gum (LBG) has been characterised using both compression and shear measurements. Slip effects caused by syneresis of the κ-carrageenan during dynamic shear measurements were eliminated through the use of pre-formed gels glued between parallel plates. The improved measurement system yielded very high G ′ values of the order 10,000–30,000 Pa for 1% κ-carrageenan gels in 0–0.2 M added KCl conditions. The introduction of LBG showed no synergistic peak in gel strength ( G ′ and E ) at any KCl concentration when the total polymer concentration was kept constant. Measurements of Young's modulus for the same gels yielded a Poisson's ratio of 0.5. Compression rupture stress and strain were also monitored to study the interaction between the two gums. A peak in rupture was observed at a κ-carrageenan/LBG ratio of ∽6:4.