Microfluidization of liquid egg yolk: Modelling of rheological characteristics and interpretation of flow behavior under a pipe flow

Aim of this research was to study the effects of microfluidization [103 (MEY1), 138 (MEY2), 172 (MEY3), and 207 (MEY4) MPa] on the rheological characteristics of liquid egg yolk (EY). Apparent viscosity of EY increased as the microfluidization pressure increased. Power law parameter, K increased from 0.29 (MEY0) to 8.56 (MEY4), while n decreased from 1.01 (MEY0) to 0.57 (MEY4), demonstrating shear thinning characteristics. Power law, Bingham, Casson and Herschel–Bulkley models described the experimental data (R2 ~ 0.99) well. Thixotropic and anti-thixotropic behavior of microfluidized EY was observed in time-dependent rheology. Furthermore, as microfluidization pressure increased, Weltman model parameters (A and B) increased. In dynamic rheological analysis, MEY0 (control), MEY1, and MEY2 showed elastic solid-like behavior, while EY microfluidized at higher pressure showed liquid-like behavior (MEY3 and MEY4). Furthermore, damping factor (DF) of MEY3 and MEY4 was found to be >1 across the entire applied strain. The Reynolds numbers of the control and microfluidized EYs were computed, for microfluidized EY, a laminar flow has been observed.