Designing Equilibrium Modified Atmosphere Packages for Fresh-cut Vegetables Subjected to Changes in Temperature

Storage temperature is never constant in the distribution chain of fresh foods. Due to the temperature dependence of respiration of fresh produce and O2permeability of a packaging film, fluctuating temperatures result in changes of the internal O2and CO2concentration of Equilibrium Modified Atmosphere (EMA) packaged fresh produce. Therefore, the design of EMA packages was improved by adding mathematical models describing the effect of temperature, O2and CO2levels on produce respiration. The influence of temperature on respiration was described by an Arrhenius type of equation while the influence of O2and CO2on respiration was modelled by a Michaelis-Menten kinetic for 10 types of fresh-cut produce. Compared to unprocessed vegetables a higher temperature dependence of cut/shredded produce was observed. An integrated mathematical model characterized the effect of produce type, produce weight, temperature, O2and CO2dependence of produce respiration, film type, package area and temperature dependence of film permeability for O2in order to predict the internal O2concentration of an EMA package which was designed for equilibrium concentration of 3 mL/100 mL O2at 7°C. The model was validated by packaging 10 types of fresh-cut vegetables and comparing equilibrium O2levels with those predicted at six different temperatures between 2 and 15°C.