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.