Abstract The objective of this work was to evaluate the drying performance, the quality of the corn grain and the contamination by polycyclic aromatic hydrocarbons (PAHs) using a direct-fired furnace fed automatically by wood chips. Samples were collected at five-minute intervals, 12 samples before drying and 12 samples after drying. The following experimental evaluations were carried out: dryer – performance and fuel consumption; grains – moisture content, germination, electrical conductivity, apparent specific mass, mass of a thousand grains, color and PAHs. The dryer showed an average efficiency of 83.61%. The average consumption of wood chips was 0.3932 kg of chips per kilogram of evaporated water. Differences were observed in the grains after drying for the characteristics of mass of a thousand grains, apparent specific mass, germination and electrical conductivity. The average concentrations of PAHs in corn grains were higher than the maximum values allowed by the European Union legislation.

Abstract The objective of this study was to evaluate the drying system using a dryer with furnace automatically fed with eucalyptus chips and another dryer manually fed with eucalyptus firewood, as well as assessing the quality of corn grains. Harvest was mechanically performed and the grains were transported by trucks to the storage unit for drying. Corn grain drying was conducted in mixed-flow dryers with a nominal capacity of 100 tons per hour. For air heating, two direct-fired furnaces were used, one automatically fed with eucalyptus chips and the other manually fed with firewood. Corn grains were evaluated for moisture content, apparent specific mass, thousand-grain weight, polycyclic aromatic hydrocarbons (PAHs), electrical conductivity and color. Drying corn grains with direct fire using firewood or chips as fuel causes contamination by PAHs. In general, the use of firewood or chips did not influence the quality of thousand-grain weight, apparent specific mass and color, while the use of chips increased electrical conductivity. It is essential that research advances in this subject, prioritizing the contamination of food, with proven carcinogenic activity, which should be treated as a high risk to public health.

Abstract Caffeine is naturally present in several foods, being one of the most consumed dietary ingredients in the world; however, excessive intake may cause health concerns. This study evaluated caffeine levels in teas and their infusions, the transference rate during brewing, and estimated caffeine intake from tea infusion. Brands and batches of 4 types of teas were analyzed for caffeine content by high performance liquid chromatography with a diode array detector. Mate tea was the one that presented lowest levels (6.1 to 13.2 mg/g) while Camellia sinensis teas were from 14.3 to 34.8 mg/g. There were statistical differences between different types, brands and batches. Caffeine levels in infusions followed the same pattern of the leaves, with mate tea presenting lowest levels. Caffeine percentage of transference from leaves to infusion varied from 51.5 to 85.2%. Caffeine intake was estimated to be up to 191.4 mg/day. Tea may be considered an important source of caffeine intake for heavy tea drinkers.