Correlation Between Transient Rotational Viscometry and a Dynamic Oscillatory Test for Viscoelastic Starch Based Systems

Gelatinized starch formulations including lipids and xanthan gum, typical of viscoelastic foodstuffs, were analyzed using a rotational viscometer (transient conditions) and an oscillatory rheometer. Ultra‐rapid and slow freezing processing conditions, which can modify product stability, were also tested. Transient shear stress curves showed a typical overshoot and a structural breakdown; the Bird‐Leider model satisfactorily fitted these curves. Model parameters were correlated with characteristic peak stress (αmax), peak time (tmax) and relative overshoot corresponding to the α vs time curve. Relationships between transient shear stress data and dynamic measurements (G′, G*, δ) for viscoelastic ranges were found for the starch‐based systems and were used to assign a physical meaning to Bird‐Leider parameters. Viscoelastic starch systems were grouped in different zones of the correlation diagrams based on structure properties like rigidity, stability to the applied strain and fluid characteristics after breakdown.