Throughout its life cycle, an ontology may change in order to adapt to domain changes or to new usages.
This paper presents an ontology evolution activity  applied to an ontology dedicated to the annotation of experimental data in food, and a plug-in, DynarOnto, which assists ontology engineers for carrying out the ontology changes. Our evolution method is an a priori method which takes as input an ontology in a consistent state, implements the changes selected to be applied and manages all the consequences of those changes by producing an ontology in a consistent state.