Effect of Persian Gum on Whey Protein Concentrate Cold Set Gel at Neutral and Acidic Condition

Proteins and polysaccharides have an important influence on the structure, texture and stability of food systems and their mixed gel can be used as a model for soft solid products. Production of cold set gelation based on protein is a novel food processing method that would positively affect the physical properties of the product. In this research, the mixed gels of whey protein concentrate (WPC) and Persian gum (PG) were produced using the cold set gelation at neutral pH (induced by CaCl2) and acidic pH (by Glucono delta- lactone addition). The dynamic rheological properties, syneresis, and the microstructure of gels were investigated by scanning electron microscope (SEM). The strong electrostatic bonding at the acidic condition resulted in the lower required WPC concentration (4% wt.) comparing to the neutral gelation condition (7% wt.). Both cold set methods required protein concentrations below the critical value of whey protein at the heat-set gel method (10-12% wt.). The results showed more PG concentration at the neutral pH, the higher viscoelastic moduli values of the mixed protein gels. However, the effect of gum on rheological moduli changes for the acidic gels, were very small. Increasing the Persian gum concentration significantly decreased the syneresis in the both gel formation methods. The results of this research reveals the potential of cold set gelation of WPC- PG mixed biopolymers in the production of a range of different gels.