Abstract : In this paper, we present the implementation of a dedicated software, MAP-OPT, for optimizing the design of Modified Atmosphere Packaging of refrigerated fresh, non-respiring food products. The core principle of this software is to simulate the impact of the dynamic of gas (O2/CO2) exchanges on the growth of gas-sensitive microorganisms in the packed food system. In its simplest way, this tool, associated with a data warehouse storing food, bacteria and packaging properties, allows the user to explore his/her system in a user-friendly manner by adjusting/changing the pack geometry, the packaging material and the gas composition (mixture of O2/CO2/N2). Via the @Web application, the data warehouse associated with MAP-OPT is structured by an ontology, which allows data to be collected and stored in a standardized format and vocabulary in order to be easily retrieved using a standard querying methodology. In an optimisation approach, the MAP-OPT software enables to determine the packaging characteristics (e.g. gas permeability) suitable for atarget application (e.g. maximal bacterial population at the best-before-date). These targeted permeabilities are then used to query the packaging data warehouse using the @Web application which proposes a ranking of the most satisfying materials for the target application, i.e. packaging materials whose characteristics are the closest to the target ones identified by the MAP-OPT software. This approach allows a more rational dimensioning of MAP of non-respiring food products by selecting the packaging material fitted to “just necessary” (and not by default, that with the greatest barrier properties). A working example of MAP dimensioning for a strictly an aerobic, CO2-sensitive microorganism, Pseudomonas fluorescens, is proposed to highlight the interest of the software.