Modeling of rheological characteristics of liquid egg white and yolk at different pasteurization temperatures

Knowledge the rheological properties is critical in processing, handling, process design, product development and quality control. In this study, the flow curves and time-dependent flow properties of the liquid egg white and yolk were assessed at different temperatures of pasteurization (50, 55 and 60 °C) and ambient temperature (25 °C) by using concentric cylinder viscometer. The shear rate range was 7.92–54.12 s⁻¹ for liquid egg white and 1.02–33.6 s⁻¹ for liquid egg yolk. Both liquid egg white showed pseudoplastic and thixotropic behavior in studied shear rates. Forward and backward measurements of the flow curves were modeled and yolk fitted by the power law model and Herschel–Bulkley model well described egg white experimental data. The consistency, behavior indexes, apparent viscosity and yield stress, affected by temperature and were expressed by an Arrhenius-type equation. The value obtained from C value of the three-point system and the hysteresis loop between forward and backward curves showed the thixotropy behavior of egg white and yolk which decreased by increasing temperature. The good agreement between predicted and observed values confirmed the reliability of the equations proposed for describing the flow behavior of the egg white and yolk.