Modified Atmosphere Container with Time-Controlled Gas-Diffusion Tube for Preserving Fresh Produce

Abstract

The concept of a fresh produce container equipped with a time-controlled gas-diffusion tube was proposed and tested for its effectiveness at modifying the internal atmosphere of the container beneficially, thus preserving the quality of stored spinach. The time-controlled closing/opening of the properly dimensioned diffusion tube was shown to be useful in attaining a modified atmosphere (MA), which is helpful for quality preservation. A mathematical model of the mass balance of gases in the container, taking care of diffusive gas fluxes through the plastic wall and the tube, convective hydraulic gas flow through the tube and produce respiration, was adopted from the literature and constructed to estimate the gas composition under a variety of design and operation variables, enabling optimization of the system. Cycle time did not affect the averaged container atmosphere at equilibrium, but it did affect the fluctuation levels of the gas composition. Functional relationships between the spinach container atmosphere (i.e., O2 and CO2 concentrations) and independent control variables (i.e., tube dimensions and closed time ratio) were formulated and used to find a container design that gives an MA in the optimal window. A designed prototype container was able to give an optimal MA in agreement with design estimates and offer better spinach quality than the perforated control package, thus verifying the concept and model proposed. Practical Applications A time-controlled opening of gas-diffusion tube is an innovative concept to attain a desired MA in a fresh produce container. The time-controlled opening/closing of a properly dimensioned diffusion tube can be programmed using mathematical modeling to attain an MA that is conducive to the produce quality. Proper combination of the closed time ratio and tube dimension yielding the optimal atmosphere of O2 and CO2 concentrations can be found by the approach given in this study. Use of the developed concept can be applied to the reusable containers or packages keeping the product quality and extending the shelf life in the produce supply chain.