CO2 levels, technical breakage and quality of maize grains stored under different conditions

Abstract

The use of CO2 sensors has been reported as an effective tool in the early detection of signs of deterioration, allowing good accuracy in decision-making about the quality of stored grains. The objective of this study was to quantify the CO2 levels produced by maize grains stored at ambient temperature in a prototype silo, with initial moisture contents of 14, 16 and 18% w.b., and to evaluate the quality of the product over time and the technical breakage. Analyses of moisture content, ash, proteins, lipids, Hue Angle (color), germination and electrical conductivity were performed. Inside the silos, the amount of CO2, relative air humidity and temperature were monitored every hour. Grain quality evaluations were carried out at four storage times (0, 30, 60 and 90 days). A completely randomized design in a 3 × 4 factorial scheme with six replicates was used. Grains with higher moisture contents showed higher technical breakage and losses associated with CO2 emissions. Moisture content, protein, lipids, germination, bulk density, lightness and chroma decreased over time, while the electrical conductivity increased, resulting in greater damage to membranes and loss of quality of maize grains. Monitoring of CO2 in the grain mass is a good tool to assess the quality of grain, and higher initial moisture content caused greater level of CO2 emission and reduction in quality of maize grains.