Rheology of acid-induced sodium caseinate gels containing added gelatin

The influence of alkali-processed (type B) gelatin on the rheology of sodium caseinate gels made by acidifying with glucono-δ-lactone has been investigated at 25 °C. At low ionic strength, the presence of gelatin (0.1–1.5 wt%) has been found to lead to a moderate increase in gelation time, a slight lowering of the critical gelation pH, a change in the shape of the plot of storage modulus versus time, a lowering of the value of the ‘final’ storage modulus, and little change in the range of the linear viscoelastic region. The extent of recovery of the final storage modulus after intense shearing was substantially reduced in the presence of just 0.1 wt% gelatin, and it decreased further with increasing gelation content. Addition of salt (0.1–0.3 M NaCl) had a strong influence on the time-dependent rheology observed during the acid-induced gelation, leading to a substantially increased gelation time and a reduced gelation pH.