A Meta-study of the Permeance of Perforated Packaging Films to Oxygen and Carbon Dioxide

The use of perforations expands the applicability of modified atmosphere packaging to dynamically regulate the internal atmosphere composition and extend the shelf life of fruits and vegetables, especially for highly respiring products. Quantifying the impact of the perforation profile on the package permeance is key to design a best package, and various approaches have been proposed in literature. The goal of this review is to provide a unified assessment of all these previous works by applying a meta-analysis that pools together the published data for both simple perforations in a plastic film and for plug implements. Models reviewed include lumped capacity models (application of Newton’s convection law or variations of it), diffusional models (both Fick’s diffusion corrected for end effects in different manners and Stefan-Maxwell’s equations) and hydrodynamic models (using Poiseuille’s flow equation with end corrections). It was found that all data published and reviewed could be pooled together quite coherently and that it clearly shows that the effective permeance increases significantly with decreasing diameters. The concentration gradient across the package also showed some relevance. The effective permeance of a perforated package was found to be approximately what would be expected from dimensionless correlations for convection coefficients from flat planes and therefore this approach is suggested to provide a unified, robust, yet simple, analysis to estimate gas permeance and thus permit an efficient intelligent engineering design of packages. The impact of the convection coefficients in the optimum perforation profile is shown using strawberries as a case study.