Effect of Persian gum and Xanthan gum on foaming properties and stability of pasteurized fresh egg white foam

摘要

Pasteurization process results in undesirable effects on foaming properties and stability of liquid egg white. Persian gum (PG) as native hydrocolloids and Xanthan gum (XG) (in three levels) were added to liquid egg white in order to improve the foaming properties of the final solution prior to pasteurization. The viscosity increment of egg white was the natural consequence of addition of XG and PG. By addition of hydrocolloids to egg white solution, the solution's flow behavior changed from Newtonian to Pseudoplastic and flow curves were fitted to power law model consequently. Both hydrocolloids showed positive effects on foam stability in all levels, yet their negative effect on overrun and foam density was undeniable. High concentrations of XG and PG (0.1%=) resulted in the improvement of foam texture, while XG exhibited the greatest effect on foam elasticity through physical interaction with unfolded proteins. Analyzing microscopic images of foam bubbles, owing to different bulk viscosity of samples, showed negative effect of over beating for some samples while in some others the whipping time was inadequate to reach the maximum gas phase.