Design of perforated packages to preserve fresh produce considering temperature, gas concentrations and moisture loss

In order to properly preserve fresh produce such as fruits and vegetables, the packaging system must have a suitable configuration to reduce its metabolic processes, microbial activity and deterioration. For this, it is necessary to establish an equilibrium modified atmosphere packaging (EMAP) with favorable concentrations of O₂ and CO₂, relative humidity (RH) and storage temperatures that do not result in chilling injury. The EMAP system is established once a balance is reached between the product's metabolism and the gas transfer through the package. For this study, a mathematical model has been developed to estimate the change in gas levels in perforated packages by considering their configuration, the respiration and transpiration in the product, the storage conditions and by using the appropriate mass and heat differential balance equations. From the developed model, a design strategy is proposed to configure the packaging system for a defined product to rapidly establish an EMAP with low O₂ and moderate CO₂ levels in the headspace to reduce the product's metabolic processes and inhibit the microbial growth. Likewise, a high enough relative humidity (80-90%) to avoid excessive water evaporation and weight loss, but minimizing the possibility of saturation inside the package to avoid moisture condensation that contributes to deterioration in the product. To validate the design strategy, two different products, banana and tomato fruits, were taken as example and packaging materials with different permeation rates to O₂, CO₂ and water vapor such as polypropylene (PP), polylactic acid (PLA) and ethylene vinyl alcohol (EVOH) were used to establish a suitable packaging configuration for each product.