CO2 DYNAMICS AND QUALITY OF CORN GRAINS STORED IN HERMETIC AND NON-HERMETIC ENVIRONMENTS

Abstract

Brazil has been one of the countries with the highest corn production and productivity rates. Developments in the production sector are putting pressure on post-harvest care, in terms of storage capacity and product conservation conditions. Currently, the storage capacity does not meet the needs and alternative forms of storage in bag silos have been adopted by storage units. Bag silos are hermetic infrastructures which, apart from their cost, offer advantages in terms of losses due to biotic factors, guaranteeing greater availability and quality when good management practices are adopted. Thermometry has been used as the main mechanism for managing stored grains, but usually by the time the hot spots are detected, the damage has already occurred, and efficiency depends on the distribution of the cables in the storage structure. The use of CO2 sensors has been reported as a complementary and effective measure in the early detection of deterioration signs, allowing for good accuracy in decision-making. In view of this, the aim of this work was to evaluate the quality of grains stored with different initial moisture contents, both hermetically and non-hermetically, as well as their relationship with the dynamics of CO2 levels, temperature and relative humidity in the grain mass. An experiment was carried out in a completely randomized design, with a 2 × 3 × 6 factorial scheme, corresponding to two storage conditions (hermetic and non-hermetic), three initial moisture contents (14, 16 and 18% wb), six storage times (0, 30, 60, 90 and 120 days) and three replications. Throughout storage, CO2 concentrations, temperature and relative humidity in the grain mass and in the external environment were monitored using CO2 sensors. The physical properties, color, proximal composition, dry matter loss, water activity, grain integrity using X-ray images and scanning electron microscopy, insect and fungal damage, as well as the quality of the oil extracted over the 120 days of storage were also assessed. The data was evaluated using regression models, t-test, correlation and multivariate analysis, using RStudio 4.3.2® software package. It was concluded that the temperature, relative humidity and CO2 concentrations were influenced by the storage conditions, with the values increasing with the increase in initial moisture content and storage time; the condition of higher moisture content was generally more detrimental to the grain quality, as well as the extracted oil, with greater intensity for the grains stored hermetically. With regard to the classification of the grains, for a moisture content of 14% wb, storage can be carried out up to 120 or 90 days for hermetic or non-hermetic conditions, with 30 days being the maximum tolerable for conditions with a moisture content of 16 and 18% wb.