Investigation of Linear Viscoelastic Properties of Xanthan-Carob Mixture in Sol and Gel States

Synergistic interactions between xanthan (X) and carob (C) were investigated by studying the linear viscoelastic behavior of X, C, and X/C mixtures at sot and gel states. At the solution state, storage modulus (G') dominates the linear viscoelastic properties of X/C mixtures. The gelation temperature (52 to 57 degrees C) was weakly dependent on the xanthan fraction (phi(x)) in the mixture. The phi(x) also had a strong effect on G' until phi(x)=0.5. The elastic active network concentration (EANC) of X/C gels was estimated from the pseudo-equilibrium modulus. The EANC for systems with phi(x)=0.25, 0.5, 0.75, and 1 at 1% total concentration was 2.3, 4.4, 4.1, and 0.32 (x 10(-3) mol/m(3)), respectively. The maximum synergistic effect was observed at about phi(x)=0.5. The G' at the transition state of X/C mixed gel was proportional to omega(3/2) at omega>omega(tr) (the onset transition frequency) compared to the theoretical limit of omega(1/2).