High pressure homogenization (HPH) is a non-thermal technology that has been widely studied as a partial or total substitute for thermal food processing. The present work evaluated the effect of HPH on the rheological properties of a fruit juice serum model, designed to be similar to tomato juice serum. Product viscosity decreased due to the increase in homogenization pressure, and could be modelled well using two functions (power-sigmoidal and exponential; R-2 > 0.98). The serum model processed at 200 MPa showed a viscosity decrease of 20% when compared to the original. Since fruit juice rheology is defined by the interactions occurring between the dispersed phase (suspended particles) and the solution (serum), the expected fruit juice behaviour was then discussed. (C) 2012 Elsevier Ltd. All rights reserved.