Modelling of rheological behaviour of guava, pomelo and soursop juice concentrates via shear rate-temperature-concentration superpositioning

Abstract

The steady-state flow test was conducted on pink-fleshed guava, pink-fleshed pomelo and soursop juice concentrates using a rheometer to understand its rheological behaviour. The power law model was used and a master-curve was created using the shear rate-temperature-concentration superposition technique to predict rheological properties from a wide range of temperatures and concentrations. All three juice concentrates undergo a double horizontal shift whilst the pink-fleshed guava required an additional vertical shift. The final equations show shear-thinning behaviour of pink-fleshed guava, pink-fleshed pomelo and soursop with flow behaviour index of 0.2217, 0.7507 and 0.6347, respectively. The final master-curve predicts shear stress at wide range of shear rates, i.e. between 10⁻² and 10⁶ s⁻¹ for the pink-fleshed guava, 10⁰ and 10⁶ s⁻¹ for the pink-fleshed pomelo and 10⁰ and 10⁷ s⁻¹ for the soursop. The results provide useful information and effective technique to predict fruit juice concentrates behaviour affected by heat changes during processing.