Simulation of Gas and Water Vapor Exchange in Perforated-film Modified Atmosphere Packaging under Dynamic Storage Conditions

Abstract

　A mathematical model and computational algorithm were developed for simulation of O₂, CO₂, N₂, and water vapor exchange in perforated-film modified atmosphere packaging as a means of determining optimal packaging conditions for dynamic distribution environments that involve changes in temperature and humidity. The computational results obtained using the algorithm were validated experimentally. The mathematical model includes the phenomena of convection and diffusion through the film perforations. In the computational algorithm, the temperature and humidity of the atmosphere outside the package are read at intervals of Δt and the volume and concentration of O₂, CO₂, N₂, and water vapor inside the package, together with cumulative transpiration, CO₂ evolution, and water vapor condensation, are computed. Some differences were observed between the computed and experimentally measured values of O₂ and CO₂ concentrations and the changes in sample weight. Nonetheless, the results of the computation, based on the algorithm, were generally in good agreement with the experimental results, which were thereby validated. The above-mentioned differences were attributable to increase in the effective permeability of a perforation due to airflow outside the package, which was not included in the computational assumption related to intraperforation diffusion. Further improvement can be achieved by adjusting the effective permeability of the perforation for the external atmospheric flow.