Physical properties and quality of corn grains stored at different initial moisture contents under hermetic and non-hermetic conditions

The aim of this study was to evaluate the dynamics of the CO₂ concentration and its relationship with the quality of corn grains stored at different initial moisture contents under different conditions. The experiment was conducted in a completely randomized design, with a 2 × 3 × 5 factorial scheme and 3 replications. A sensor was inserted into the grain mass to measure CO₂, temperature and relative humidity levels at 1-h intervals for up to 120 days, and quality assessments were performed every thirty days via physical properties and grain classification (official Brazilian standard IN 60/2011). The data were subjected to analysis of variance, followed by a t-test for storage conditions and linear regression for initial moisture content and storage time. The variation in temperature, relative humidity and CO₂ resulted in greater metabolic activity for the non-hermetic condition and higher initial moisture content; grains stored with an initial moisture content of 14% wb presented lower levels of deterioration, with higher bulk density values and lower grain mass porosity; color variation increased as a function of time and initial moisture content; grains stored under hermetic conditions changed to type 2 at 120 days for an 18% wb initial moisture content, whereas in the non-hermetic storage, the changes began after 30 days for 16 and 18% wb, whereas for 14% wb, the change occurred at 120 days. The integrated use of temperature sensors, combined with relative humidity and CO₂ monitoring, makes CO₂ sensors valuable tools for preventing quality loss during storage.