Effect of Ca(2+), Fe(2+) and Mg(2+) on rheological properties of new food matrix made of modified cell wall polysaccharides from apple.

A new food matrix made of modified cell wall polysaccharides (MPS) from apple pomace was developed. In this experiment, an effect of metal divalent ions: calcium, magnesium and iron ions on rheological properties of MPS was studied. An increase of Ca(2+) or Fe(2+) concentration in MPS suspensions significantly increased viscosity as well as elastic (G') and viscous (G″) moduli. Contrary, Mg(2+) addition caused a significant decrease of viscosity, G' and G″. Herschel-Bulkley's model fitted to shear stress vs. shear strain (flow curves) showed that calcium and iron ions increased pseudoplasticity and viscosity proportionally to concentration. The addition of any studied metal ions to MPS increased thixotropic effect. A temperature at the gel point increased when concentration increased to 9mM, then the gel points appeared at lower temperatures again for higher concentrations. This study showed that the MPS is an effective texture modifier with a controlled function by metal ions.