Model-based electronic control device for storage and transport of fresh produce under modified O2 and CO2 atmosphere

Efficient storage and transport of fresh produce are critical for maintaining product quality and minimising postharvest losses across the supply chains. Temperature fluctuations and package/container gas compositions, particularly of oxygen (O2) and carbon dioxide (CO2), can accelerate respiration, leading to spoilage and economic loss. Existing controlled atmosphere systems often rely on gas sensors, complex control units and infrastructure, making them economically unfeasible for low-cost storage or transport applications. Modified Atmosphere (MA) systems, including perforated packages and membrane-based storage boxes, are ineffective under dynamic/variable environmental conditions, such as temperature, O2 and CO2 composition, as they are unable to modify the gas transmission rates or their permeability in real-time. This study addressed this gap through the development and validation of a stand-alone, compact, microcontroller-based gas control system that dynamically regulated dual gases such as O2 and CO2 without the need for gas sensors or external gas cylinders, making it suitable for MA storage and transport of different types of fruit and vegetables. The system includes a miniature air blower and tube for fresh air exchange to regulate O2, a second blower to direct air through a soda-lime reactor within the box for CO2 removal, and a thermistor to monitor the fresh produce temperature. A Teensy microcontroller was used to run a temperature-dependent mathematical model to predict the respiration rate of the stored produce and calculate the required blower ON frequency (BOF) for both O2 and CO2 control. An e-paper display provided real-time updates of temperature, predicted gas concentrations and respiration rate. The research was structured into four hypotheses. The first hypothesis included the development of a mathematical model to predict respiration rates based on dynamic temperature and gas composition. This model integrated the Arrhenius equation to capture the effects of temperature, the Michaelis–Menten kinetics to describe O2 dependence and an uncompetitive inhibition term to test the influence of CO2. The internal gas composition was governed by the mass balance of gases between the fresh produce respiration and the blower airflow. This model enabled the calculation of blower ON time to regulate O₂ concentration in real-time based on fresh produce temperature inside the box. Experimental validation using 25 kg of broccoli in a 190L box demonstrated that the system could maintain O₂ at 3.8 ± 0.29% under fluctuating temperatures (4–23°C) for 8 days, while also preserving product quality with minimal weight loss (