Rheological properties of mixtures of kappa-carrageenan from Hypnea musciformis and galactomannan from Cassia javanica

Mixed gels of kappa-carrageenan (kappa-car) from Hypnea musciformis and gal actomannans (Gal) from Cassia javanica (CJ) and locust bean gum (LBG) were compared using dynamic viscoelastic measurements and compression tests. Mix ed gels at 5 g/l of total polymer concentration in 0.1 M KCl showed a syner gistic maximum in viscoelastic measurements for kappa-car/CJ and kappa-car/ LBG at 2:1 and 4:1 ratios, respectively. The synergistic maximum obtained f rom compression tests carried out for mixed gels at 10 g/l of total polymer concentration in 0.25 M KCl was the same for both kappa-car/CJ and kappa-c ar/LBG gels. An enhancement in the storage modulus (G') and the loss modulu s (G ") was observed in the mechanical spectra for the mixtures in relation to kappa-car. The proportionally higher increase in G " compared with G', as indicated by the values of the loss tangent (tan delta), suggests that t he Gal adhere non-specifically to the kappa-car network. (C) 2000 Elsevier Science B.V. All rights reserved.