A geometrical interpretation of large amplitude oscillatory shear (LAOS) in application to fresh food foams

• LAOS measurement and FCT calculations were done for wet foams.
• Supplementation with inulin stabilize structure of foam.
• Supplementation with xanthan gum increases the tendency towards flow of foam.

In this research, we studied the rheological properties of wet food foams, consisting of egg white protein, inulin and xanthan gum. The rheological analysis was carried out using the large amplitude oscillatory shear (LAOS) technique. For the obtained results, we constructed two types of Lissajous figures in deformation/stress and shear rate/stress coordinate systems. A geometrical decomposition of the obtained figures was performed, which allowed the isolation of stress values for nonlinear pure elastic and pure viscous properties accordingly. With the use of the Fast Chebyshev Transformation (FCT) analysis, we were able to obtain the values of the Chebyshev coefficients. The knowledge of the elastic and viscous Chebyshev coefficients allowed for the interpretation, with high resolution, of nonlinear rheological properties of the obtained foams. It was found that supplementation with inulin stabilizes the structure of a foam based on egg white protein only. Supplementation with xanthan gum, however, increases the tendency towards flow.