PREDICTING STEADY-STATE OXYGEN CONCENTRATIONS IN MODIFIED-ATMOSPHERE PACKAGES OF TOMATOES

Mathematical procedures for predicting steady-state O2 concentrations for a range of packaging conditions for modified-atmosphere packages (MAP) of 'Heinz 1370' tomato (Lycopersicon esculentum) were developed and tested. The relationship between O2 consumption rate and O2, concentration was determined using O2 depletion data collected by enclosing tomatoes in jars and sampling head space O2 concentration over time. The fitted function was then used in conjunction with the input variables film permeability to O2 (P(O2)), film surface area (A), and fruit weight in packages (W(p)) to develop an equation to predict steady-state O2 concentrations for different packaging ratios (A/W(p)) and film permeabilities. Prediction curves showing steady-state O2 concentration for packaging ratios in the range of 1 to 12 closely resembled best-fit curves of experimental data. Increasing temperature from 20 to 28C had little effect on in-package O2 concentration, but decreasing temperature from 28 to 10C led to higher in-package O2 concentrations. The predictive equation developed can be used to select appropriate films and optimize packaging ratios to achieve desired steady-state O2 concentrations for MAP of tomatoes.