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.

RESUMO O objetivo nesse trabalho foi avaliar o comportamento da secagem e a qualidade das sementes secas com ar natural em frutos de crambe submetidos a diferentes fluxos de ar em secadores estacionários. As secagens foram realizadas em dois períodos, uma em julho e outra em setembro do ano de 2014. O experimento compreendeu três tratamentos "A", "B" e "C" que consistiram na secagem dos frutos de crambe com ar natural em secador estacionário com fluxos de ar de 10,08 m3 min-1 ton-1; 15,05 m3 min-1 ton-1; 25,03 m3 min-1 ton-1, respectivamente e uma testemunha "T" composto por frutos de crambe com teor de água inicial sem passar pelo processo de secagem. Após as secagens, foram realizados testes de teor de água, germinação, índice de velocidade de germinação e condutividade elétrica para comparação dos tratamentos. Os dados obtidos foram submetidos à análise de variância e comparação de médias pelo teste de Tukey a 5% de significância. Dentre os fluxos de ar utilizados no experimento em ambas as secagens com ar natural nos meses de julho e setembro, não houve interferência na qualidade dos frutos de crambe. A secagem realizada no mês de setembro foi mais rápida e apresentou menor gasto e custo de energia elétrica quando comparada com a secagem realizada no mês de julho devido às melhores condições climáticas. Não houve diferença no tempo de secagem entre os fluxos de ar utilizados, porém, a secagem com ar natural utilizando o fluxo de ar de 15,05 m3 min-1 ton-1 mostrou ser mais rentável.

ABSTRACT The aim of this study was to assess the drying behavior and quality of crambe fruit seeds dried with natural air and submitted to different airflows in stationary dryers. Dryings were carried out in July and September 2014. The experiment consisted of three treatments of drying the crambe fruits with natural air in stationary dryers with airflows of 10.08, 15.05, and 25.03 m3 min−1 t−1 and a control treatment composed of crambe fruits with an initial moisture content without going through the drying process. After drying, tests of moisture content, germination, germination rate index, and electrical conductivity were performed in order to compare the treatments. The data were submitted to analysis of variance and mean comparison by the Tukey's test at 5% significance. Among the airflows used in the experiment in both natural air dryings in July and September, no interference was observed for crambe fruit quality. Drying carried out in September was faster and showed a lower expenditure and cost of electricity when compared to that performed in July, which is due to better climatic conditions. No difference was observed in the drying times between airflows, but the drying with natural air using an airflow of 15.05 m3 min−1 t−1 was more profitable.