Avaliação do processo de secagem com alimentação por cavacos de lenha e qualidade dos grãos de soja e milho

Abstract

In Brazil soybean and corn are the crops with the largest extensions of cultivated area and economic expression, generating income and development in the growing regions. Due to susceptibility to climatic conditions and the high moisture content during harvest, the grains need to go through the artificial drying process, which is crucial to maintain the grain quality, in addition to being the phase in which the highest energy consumption occurs. Thus, given the economic potential, food safety, the use of renewable energy sources in grains drying and the scarcity of information about the process using automatic feeding of eucalyptus chips, the objective of this work was to evaluate the performance of industrial drying with direct-fire furnace automatically fed with eucalyptus chips, the soybeans and corn grain quality, as well as contamination by PAHs. Three dryings were carried out, two with soybeans (february/2019) and one with corn (june/2019). The grains were harvested mechanically and transported to a storage unit located in the municipality of Montividiu - GO. Grain samples were collected before and after drying. During the drying, performance evaluations and specific energy consumption were performed. Soybean and corn grains were evaluated for moisture content, germination, electrical conductivity, apparent specific mass, color, acidity index (only soybeans) and PAHs. Grain drying was carried out in a mixed flow dryer (Kepler Weber, ADS). The dryings showed average efficiency above 75%, considered satisfactory for systems that use direct-fire furnace. The specific energy consumption of the soybeans drying was 8,099.50 kJ and 11,871.80 kJ to remove 1 kg of water, the difference in the results being equivalent to the specific conditions of each drying. For corn drying, the specific energy consumption to remove 1 kg of water was 7,389.35 kJ. The grains showed differences after drying for the characteristics evaluated, however, in general, for the industrial purpose of the grains, the quality was not compromised. Before drying, contamination of the grains by PAHs was detected. Drying with direct-fire furnace using wood chips promoted PAH contamination in soybean and corn grains. The average concentrations of PAHs in soybeans and corn were higher than the maximum values allowed by the European Union Legislation.