In this paper, a model structure is presented that captures product behaviour with respect to quality properties. Modelling product quality properties involves nominal (bulk) dynamic behaviour and the variation of these properties. Nominal behaviour is modelled using a limited number of basic reactions. To deal with the variation the presented model structure is extended with a three-step approximation procedure using discretised intervals. The model structure is suitable for control purposes and will contribute to closing the gap between product specialists and the system and control community. The applicability of the model structure and the possibility to describe quality properties is shown with existing models from the literature that show a good fit with the described model structure and by an industrial case study on potato storage.