Predicting Steady-state Oxygen Concentrations in Modified-atmosphere Packages of Tomatoes

Mathematical procedures for predicting steady-state O 2 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 O 2 consumption rate and O 2 concentration was determined using O 2 depletion data collected by enclosing tomatoes in jars and sampling head space O 2 concentration over time. The fitted function was then used in conjunction with the input variables film permeability to O 2 (P O2 ), film surface area (A), and fruit weight in packages (W p ) to develop an equation to predict steady-state O 2 concentrations for different packaging ratios (A/W p ) and film permeabilities. Prediction curves showing steady-state O 2 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 O 2 concentration, but decreasing temperature from 28 to 10C led to higher in-package O 2 concentrations. The predictive equation developed can be used to select appropriate films and optimize packaging ratios to achieve desired steady-state O 2 concentrations for MAP of tomatoes.