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

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 65 ºC. 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.

Fungi associated with Paspalum guenoarum seeds: their impact on physiology and control / Fungos associados com sementes de Paspalum guenoarum: seus impactos na fisiologia e controle

ABSTRACT: Of the natural pastures grown in southern Brazil, those of the genus Paspalum are the most important. One of the factors that hinder their cultivation is the availability of quality seeds, that are often compromised by the presence of fungi. This study determined the in vitro sensitivity of Paspalum guenoarum ecotype azulão seed-associated fungus to certain fungicides and to measure the efficiency of chemical treatments for fungal control and seed physiological performance. Bipolaris micropus, Epicoccum sorghinum, Curvularia geniculata and Fusarium incarnatum associated with seeds were tested in vitro against Carbendazim; Tiram, Fludioxonil; Metalaxil-M, Carboxina; Tiram and Tiofanato-metílico at 0, 1, 2.5, 5, 10 and 30 µg/mL. This experiment was conducted in a completely randomized design (factorial 4 × 4 × 6). Qualitative variables were compared using the Tukey test (P ≤ 0.05) and quantitative variables were subjected to regression analysis. Carbendazim; Tiram and Fludioxonil; Metalaxil-M had the best fungicidal performances, each inhibiting three of the four fungi with LD50s below 1 µg/mL. Subsequently, these two fungicides were used alone or in combination in the in vivo test. A completely randomized design was used and the means were compared using the Tukey test (P < 0.05). The chemical treatment of the seeds resulted in improvement of five of the six evaluated physiological parameters. The identification of the primary fungi associated with Paspalum seeds reported in this research, as well as damage done to them, can be diminished using appropriate measures such as seed treatments.

RESUMO: Das pastagens naturais cultivadas no sul do Brasil, as do gênero Paspalum são as mais importantes. Um dos fatores que dificultam o cultivo é a disponibilidade de sementes de qualidade, muitas vezes comprometidas pela presença de fungos. Os objetivos deste estudo foram determinar a sensibilidade in vitro de fungos associados a sementes de Paspalum guenoarum ecótipo azulão a determinados fungicidas, medir a eficiência de tratamentos químicos para controle desses fungos e o desempenho fisiológico das sementes. Os fungos associados às sementes, Bipolaris micropus, Epicoccum sorghinum, Curvularia geniculata e Fusarium incarnatum foram testados in vitro contra Carbendazim; Tiram, Fludioxonil; Metalaxil-M, Carboxina; Tiram e Tiofanato-metílico em 0, 1, 2,5, 5, 10 e 30 µg/mL. Este experimento foi conduzido em um delineamento inteiramente casualizado (fatorial 4 × 4 × 6). As variáveis ​​qualitativas foram comparadas pelo teste de Tukey (P ≤ 0,05) e as variáveis ​​quantitativas foram submetidas à análise de regressão. Carbendazim; Tiram e Fludioxonil; Metalaxil-M tiveram os melhores desempenhos fungicidas, cada um inibindo três dos quatro fungos com LD50 abaixo de 1 µg/mL. Posteriormente, esses dois fungicidas foram utilizados isoladamente ou em combinação no teste in vivo. O delineamento experimental foi inteiramente casualizado e as médias comparadas pelo teste de Tukey (P < 0,05). O tratamento químico das sementes resultou na melhoria de cinco dos seis parâmetros fisiológicos avaliados. A identificação dos fungos primários associados às sementes de Paspalum relatadas neste trabalho, bem como os danos causados ​​por eles, podem ser diminuídos usando medidas apropriadas, como tratamento de sementes.

PAHs in corn grains submitted to drying with firewood.

Grain drying using firewood as fuel for air heating, with direct fire, is still widely used in Brazil. The combustion of organic material, such as wood, can generate polycyclic aromatic hydrocarbons (PAHs) which are known to have carcinogenic potential. In the present work corn grain drying was carried out at three drying air temperatures: 60°C, 60/80°C and 80°C. Following the drying process, the presence and quantification of PAH in the corn grains was investigated. After extracting the PAHs of the matrix, the material was subjected to analysis by gas chromatography with mass detector. he results showed the presence of seven compounds: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene and chrysene.