Pesticides are used globally to protect food against pest attack. This study evaluates the dissipation of bifenthrin and deltamethrin residues in unhulled rice and the translocation of these insecticide residues in husked rice stored at 25 °C in a biochemical oxygen demand (BOD) incubator for 35 days. For pesticide determination, the simple and efficient solid-liquid extraction methods with low temperature partition (SLE/LTP) followed by gas chromatography with electron capture detection (GC-ECD), for unhulled and husked rice were optimized and validated. These methods produced results of validated parameters consistent with Brazilian legislation, showing good efficiency (recovery rate above 95%) and limit of quantification (LOQ) < 0.090 mg kg−1 for bifenthrin and LOQ < 0.070 mg kg−1 for deltamethrin. There was a 40% dissipation of deltamethrin residues after 15 days of storage of the unhulled rice. For the insecticide bifenthrin, dissipation during the 35 days of storage was not verified. The remaining residues of dissipation in the rice grains were below the maximum residue level (MRL) prescribed by the law. The insecticide residues did not translocate in the husked rice grains destined for final consumption.

RESUMO Este estudo investigou o efeito de um método de secagem com razões intermitentes no tempo efetivo de secagem, consumo específico de energia e rendimento de óleo essencial de folhas de manjericão cravo (Ocimum gratissimum L.). Os testes de secagem foram conduzidos no Laboratório de Pós-colheita de Plantas Medicinais, Aromáticas e Condimentares do Departamento de Engenharia Agrícola da Universidade Federal de Viçosa, Viçosa, MG, (20° 46’ 13.5” S; 42° 52’ 23.3” N, e altitude de 665 m) em outubro e novembro de 2017. O experimento foi conduzido usando um esquema fatorial 3 × 4, incluindo três temperaturas de secagem a 50, 60 e 70 °C, com quatro processos de secagem: contínua e as três razões intermitentes seguintes de secagem/repouso em minutos 10/20, 15/15 e 20/10. O delineamento foi inteiramente casualizado e com três repetições. A aplicação da razão intermitente 10/20 reduziu o tempo efetivo de secagem e o consumo específico de energia. Quanto ao rendimento de óleo essencial, o uso da intermitência apresentou resultados diferentes para cada temperatura de secagem; os maiores rendimentos foram observados com secagem contínua a 50 °C e secagem com a razão intermitente 20/10 a 60 °C. Os resultados indicam que a secagem intermitente a 50 °C não é recomendada para preservar o rendimento de óleo essencial.

ABSTRACT This study investigated the effect of a drying method with intermittent ratios on the effective drying time, specific energy consumption and essential oil yield of clove basil (Ocimum gratissimum L.) leaves. The drying tests were conducted at the Postharvest Laboratory of Medicinal, Aromatic and Condiment Plants, from the Departamento de Engenharia Agrícola of the Universidade Federal de Viçosa, Viçosa, MG, Brazil (20° 46’ 13.5” S; 42° 52’ 23.3” W, and altitude of 645 m) in October and November 2017. The experiment was conducted by using a 3 × 4 factorial scheme including three drying temperatures at 50, 60 and 70 °C, with four drying processes: continuous drying and the following three intermittent drying/tempering ratios in minutes: 10/20, 15/15 and 20/10. The design was completely randomized and with three repetitions. The application of the 10/20 intermittent ratio reduced the effective drying time and the specific energy consumption. Regarding the essential oil yield, the use of the intermittence presented different results for each temperature of drying; the highest yields were observed with continuous drying at 50 °C and drying with the 20/10 intermittent ratio at 60 °C. The results indicate that intermittent drying at 50 °C is not recommended to preserve essential oil yields.