Two-dimensional numerical simulations for the ohmic heating of milk solutions in an annular geometry were performed using a general-purpose partial-differential equation solver, FlexPDE software. The flow, energy, and concentration equations were developed and solved for the laminar flow condition. The kinetic model for beta-lactoglobulin proposed by Toyoda and Fryer (1997) was adopted to solve the native, denatured, and aggregated protein concentration for the full-flow domain. The aim of this work is to investigate how the applied voltage and Reynolds number affect the temperature field, and the subsequent effects on the concentration profile of each protein in the solution. Results show that higher voltage causes faster disappearance of native protein concentration, especially near the wall. Depending on the applied voltage, denatured protein concentration initially increases along the axial distance, then start to decrease at different axial location. The aggregated protein concentration was found to be much higher at wall then in the bulk. Despite what are usually expected of the ohmic heating as a uniform heating method, temperature gradients were seen to be significant from the wall to the bulk solution in our case. Combined with understanding of the protein concentration distributions in the heater, the fouling tendency of milk components on the walls is discussed in this paper.