Linear viscoelasticity of carob protein isolate/locust bean gum blends

Linear viscoelastic properties of locust bean gum (LBG), carob protein isolate (CPI) and LBG-CPI aqueous dispersions were studied at different concentration and pH values. LBG and CPI dispersions show marked different linear viscoelasticity behaviour. The former system exhibits a fluid-like behaviour for all the concentrations considered (2-4 wt.%), whereas the later shows gel-like mechanical spectra. An increase in linear viscoelastic functions, G' and G ''. takes place as protein concentration becomes higher, as a consequence of a strengthening of the gel network. CPI dispersions were affected by the pH value, in agreement with the CPI solubility profile. The behaviour observed for CPI-LBG dispersions shows an apparent evolution with time, suggesting occurrence of thermodynamic incompatibility between both biopolymers that finally leads to a segregative separation of LBG-rich and CPI-rich phases. Both microstructure and viscoelastic properties of the final LBG-CPI systems are highly dependent on pH value. (C) 2010 Elsevier Ltd. All rights reserved.