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 x 3 x 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 ttest 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.