Drying of soybean grains with direct-fired furnace using wood chips: Performance, quality and polycyclic aromatic hydrocarbons

Abstract

The search for new technologies and options of activities to improve agricultural production systems are goals continuously desired by companies. Thus, the objective of this study was to evaluate the performance of soybean grain drying, using a furnace dryer automatically fed with eucalyptus chips, the quality of the grains before and after drying, as well as contamination by polycyclic aromatic hydrocarbons (PAHs). Twenty-seven samples were collected before drying and 27 samples were collected after drying, totaling 54 samples of around 1.0 kg each, at 5-minute intervals. The following experimental evaluations were carried out: dryer – performance, calorific value and fuel consumption; grains – moisture content, germination, electrical conductivity, apparent specific mass, thousand-grain weight, color, oil acidity index and polycyclic aromatic hydrocarbons. The dryer showed an average efficiency of 75.61% for drying the grains. The average fuel consumption was 21.78 kg of chip per ton of dry grains. The specific energy consumption to remove 1.0 kg of water was 11,871.80 kJ. In general, drying did not compromise the final quality of soybeans. Soybeans showed the presence of two PAHs before drying and three more PAHs appeared after drying. Average concentrations were lower than the maximum values allowed by European Union Law No 835/2011. The drying conditions used for soybean grains influenced the low formation of PAHs.