Résumé
Modified Atmosphere Packaging (MAP) relies on modification of the atmosphere inside the package in order to extend food shelf life by reducing oxidation and microbial degradation rate. In the peculiar case of inert products (e.g. meat- or fish-based food products) MAP is achieved by the interplay of two processes: (1) the transfer of gases through the packaging and (2) either the gas depletion (gain) process (gas flush or absorber). To preserve the quality of a food, MAP maintains duration of a given O2/CO2 mixture by using high barrier packaging materials. Currently, to evaluate the impact of gases on microorganisms growth, the “pack and pray” empirical methodology is used: different gases mixtures (mainly O2/CO2/N2) are successively tested on the product until the right combination (O2/CO2 ratio, package surface/volume, mass of food, etc.) is found. The use of mass transfer models concomitantly with predictive microbiology would be a more appropriate method to allow a correct design and sizing of modified atmosphere packaging systems by minimizing the number of experiments. However, this kind of tool combining mass transfer and predictive microbiology does not yet exist. Gases transfer phenomena in solid food matrix are characterised with two parameters, a thermodynamic one (solubility), and a kinetic one (diffusivity), both indispensible in mathematical models of mass transfer. The main bottleneck in the evaluation of O2 solubility and diffusivity is the quantification of dissolved oxygen in solid food matrix. This work that takes place in the context of the MAP’OPT project, funded by the French National Research Agency, aims at developing innovative, rapid and non-destructive methodologies to determine O2 solubility and diffusivity in liquid and solid food matrices. These methods are based on the use of oxygen sensors permitting quantification of O2 partial pressure by quenching of luminescence. Methodologies and first preliminary results will be presented here.