Modelling passive modified atmosphere packaging of strawberries: Numerical analysis and model validation

The aim of the present study was to develop a simple but comprehensive mathematical model for predicting molecular oxygen (O2), carbon dioxide (CO2) and temperature evolution inside modified atmosphere packages of strawberries (Fragaria x ananassa cv. San Andreas) during storage in fluctuating temperature conditions. Gas transport and heat transfer within packages were modelled with traditional transport phenomena approach. A combined Michaelis – Menten - Arrhenius respiration model for strawberries was included. For model validation, experimental assays with strawberries packaged in passive atmosphere and stored at different temperatures for 4 d were carried out. Simulated concentration of O2 and CO2 and temperature evolution inside packages were compared to experimental values and model adequacy was checked by calculation of Root Mean Square Error (RMSE). Implementation of model was done using COMSOL Multiphysics (version 3.4, COMSOL Inc., Burlington, MA). Results showed a good agreement between experimental data and numerical ones, at least as regards mass transfer. Less adherent experimental evidence was the prediction of temperature during the process. Model can be used to test different package configurations in order to achieve adequate postharvest storage conditions for shelf – life extension of strawberries.