Effects of pH and ionic strength on the rheology and microstructure of a pressure-induced whey protein gel

The effects of pH and ionic strength (I) on the properties of a pressure-induced gel from a whey protein isolate (0.2 g mL−1) were studied using a series of buffers with different pH and ionic strength (I). The rheological properties and water-holding capacity (WHC) of the gel changed in a complex pattern with pH and I but could be successfully modelled using an artificial neural network (ANN) model. The degree of cross-linking of S–S bonds was higher at pH 8.0 than at pH 5.0; consequently, a rigid gel was formed at alkaline pH values. The geometric dimensions of the microstructure decreased with increasing pH and decreasing ionic strength, and the WHC mainly depended on the geometric properties of the microstructure. These results indicate that pH and ionic strength influenced the gel properties by controlling the cross-linking reaction and phase separation that occur during gelation. They also confirmed the good potential application of ANN in studies of gelation.