In‐Line Measurement of Rheological Parameters and Modeling of Apparent Wall Slip in Diced Tomato Suspensions Using Ultrasonics

Rheological behavior of a slurry consisting of 1‐ to 3‐mm diced tomatoes suspended in tomato juice was evaluated by an in‐line measurement method based upon ultrasonics. This technique permitted the measurements of yield stress, consistency index, and apparent wall slip. The suspension exhibited a yield stress at every flow rate studied, and its value was found to be 0.79 ±0.11 Pa. The shear viscosity at different shear rates was obtained in‐line without assuming a specific constitutive equation. A comparison of Herschel‐Bulkley, Power Law, Bingham Plastic, and Casson models showed that this suspension was best characterized with the Herschel‐Bulkley model. The apparent wall slip region was successfully modeled as a Bingham fluid. This study shows the usefulness of this method for in‐line characterization of particulate tomato products.