Effect of Persian gum on whey protein concentrate cold-set emulsion gel: Structure and rheology study

In this study, the influence of Persian gum (PG) on the properties of whey protein concentrate (WPC) emulsion gel prepared through cold set gelation method (incorporation of CaCl₂) was investigated. The mean droplet size of emulsions was analyzed prior to gelation and the emulsion gel samples were characterized by rheological studies, scanning electron microscopy (SEM) and water holding capacity (WHC) measurement. Results showed PG affected the droplet size of the initial emulsions and the matrix of gel systems. Emulsions containing 0.3% w/w PG revealed higher heat stability compared to the control. A viscoelastic behavior was observed for all emulsion gels with G' being greater than G″ over the whole frequency range tested. Increasing the concentration of PG led to a change in the gel structure at pH 7. SEM images exhibited that PG at 0.3% w/w gave rise to an ordered honeycomb-like microstructure with an interconnected porous matrix of thin walls. In contrast, adding 0.6% w/w PG resulted in a non-uniform network with large pores of thick and rough walls and reduced the WHC. These findings suggest the viscoelastic properties and microstructure of WPC emulsion gel can be tailored by adjusting PG concentration for food formulations.