A new modelling approach of the thermally-induced aggregation of beta-lactoglobulin was developed in order to study thermo-mechanical process conditions that allow obtaining whey protein aggregates with specific functionalities. The modelling approach aims to describe physico-chemical phenomena (unfolding, collisions and aggregation) occurring during aggregation process and to predict the functional properties of the aggregates suspension after thermo-mechanical treatment. The model is based on Population Balance Equations and integrates different specific mechanisms of beta-lg aggregation through several parameters. These parameters are identified using experimental thermo-mechanical treatments (67-95 degrees C for different holding times) on 6% beta-lg solution with CaCl2 added (from 5.1 to 7.1 mM). For this system, the model is able to predict the residual native fraction, the aggregate size distribution and the viscosity of the aggregates suspension. The role of moderate shear in aggregate formation is well represented by the model. The model also describes successfully the effect of variations of the physicochemical environment as it is illustrated with the influence of calcium on the probability of aggregation for large particles. (C) 2014 Elsevier Ltd. All rights reserved.