A model allowing dynamic simulation involving contamination and bacterial growth in a food processing workshop is presented. Although bacterial population behaviour in controlled laboratory conditions have been extensively studied, very little is known about their dynamics on industrial processes. Simulation can provide a support to understand and analyse the effects of operational conditions on contamination and bacterial growth, by taking into account many related external factors and by testing hypotheses concerning the relative importance of these factors. The main characteristics of food processes is that they involve both continuous and discrete aspects. Continuous aspects concern the bacterial growth and their transport by air, as the discrete part refers to influencing factors such as contamination modes, cleaning operations and food processing. The DEVS formalism has been chosen as it exhibits interesting features for developing a general simulation environment. Ones of the major achievements in the DEVS formalism are the clear separation between model description and model resolution, hierarchical and modular model building in an object-oriented environment, and rule-based programming.