Modified atmosphere container equipped with gas diffusion tube automatically controlled in response to real-time gas concentration

• Fresh produce container with air access responding to measured O2 and CO2 levels.
• Low O2 and high CO2 limits can be used as control criteria for optimal atmosphere.
• Prototype for spinach maintained 8–9% O2 and 10% CO2 under temperature variations.

Fresh produce container system was constructed to have a gas diffusion tube or perforation aperture responding to real-time measured O2 and CO2 concentrations. Within the boundary of appropriate diameter and length of the diffusion tube, lower O2 and upper CO2 limits of optimal modified atmosphere could be used as criteria for control. From the mathematical simulation based on the mass balance of gases under controlled opening/closing, it was found that the atmosphere of appropriately designed container for blueberry, green pepper, king oyster mushroom and spinach is usually located on the borderline of the lower O2 limit or the upper CO2 limit without coming into zone of injurious gas concentration. This estimation was confirmed experimentally for a prototype container system of green pepper and spinach at 10 °C. The prototype system for spinach was effective in maintaining the beneficial modified atmosphere (8–9% O2 and 10% CO2) under both constant and varying temperature conditions, and thus contributed to quality preservation.