The SAOS, MAOS and LAOS behavior of a concentrated suspension of tomato paste and its prediction using the Bird-Carreau (SAOS) and Giesekus models (MAOS-LAOS)

Abstract

The SAOS and LAOS behavior of tomato paste were investigated in this study. SAOS rheology was well predicted by the semi-empirical Bird-Carreau constitutive model. The LAOS (Large amplitude oscillatory shear) behavior of tomato paste was also investigated in depth in this study and non-linear rheological properties were obtained by utilizing Ewoldt-McKinley theory. These parameters offer new insights into the rheology of tomato paste and help understand structural changes which occur at different deformations (strain) and time scales (frequency). We plotted the intracycle normalized stress vs. normalized strain in the linear and non-linear regions offered new intracycle insights and observations. Tomato paste showed an irreversible structural change in LAOS evidenced by strain softening (in the mid-oscillatory region) followed by strain hardening (in the large oscillatory region). The nonlinear flow behavior simulated by the single mode Giesekus model gave good results up to moderate strains and frequencies. These results help gain better insights at large deformations, which occur during processing and consumption.