Contamination and persistence of polycyclic aromatic hydrocarbons (PAHs) in rice grains after drying in direct-fired dryer.

Abstract

The objective of this work was to study PAHs contamination in rice grains subjected to different milling types, after drying at different air temperatures in a direct-fired dryer and using firewood with different moisture contents as a heating source. In addition to verifying the persistence of these compounds after storage. Drying of rice grains was performed in a cross-flow dryer at air temperatures of 55 and 65ºC. As heating source firewood containing different moisture contents was used. The presence of nine PAHs was detected. The drying air temperature, as well as the storage time, did not significantly influence the PAHs contamination of grains. The highest PAHs contamination was observed in grains from the brown subgroup. Grain polishing promoted a reduction in the PAH concentration. The grains subjected to parboilization showed a higher PAHs concentration. The use of firewood with higher moisture content promoted greater PAHs contamination in the grains.