Ronicely Pereira Rocha

Cinética del secado de tomillo

Los objetivos del trabajo fueran estudiar la cinetica del secado de tomillo con posterior ajuste de diferentes modelos matematicos a los datos experimentales y determinar los valores de la difusividad efectiva y energia de activacion. Para el desarrollo del experimento de secado fueran utilizadas las temperaturas 30, 40, 50, 60 y 70 oC. El diseno experimental fue de bloques completamente aleatorizados, con tres repeticiones. Para el ajuste de los modelos matematicos a los datos experimentales fue realizado el analisis de regresion no lineal, por el metodo Simplex-Quasi-Newton. Los resultados mostraron que el modelo matematico de Page obtuve un mejor ajuste a los datos experimentales, los valores de los coeficientes de difusividad efectiva variaron entre 3,69 x 10-12 e 1,19 x 10-10 m2 s-1 y el valor de la energia de activacion fue de 77,16 kJ mol-1.

Quality parameters of Cymbopogon citratus leaves during ambient storage.

The effects of storage in different packages on the essential oil content and humidity of Brazilian lemon grass (Cymbopogon citratus) leaves were studied. Lemon grass leaves were dried at 50°C to moisture content of 11% (d.b.) and stored for one year in three different plastic and paper packages. Oil content and its principal compounds were isolated by the hydro-distillation method and analyzed by GC-FID as well as GC-MS every two months. The results showed a reduction in the oil content as well as a decrease in citral and myrcene in the plant for all packages during storage. Water concentration did not significantly vary during the period in the three packages.

Evaluation of Electrical Conductivity as a Quality Parameter of Lemongrass Leaves (Cymbopogon citratus Stapf) Submitted to Drying Process

This study aims to evaluate the quality of lemongrass plants after drying at different speeds (1.0, 1.5, 2.0 m s−1), temperatures (40, 50, 60, and 70°C), and drying air control systems (manual and automatic) using electrical conductivity as a parameter for evaluation. Firstly, we evaluated the time necessary for imbibitions of material in deionized water after drying for different air speeds and control systems. Secondly, the effect of temperature in fresh and dry plants was evaluated, comparing them with contents of essential oils and the quantity of ions leached by the electrical conductivity test. According to the results, the value of liquid diffusion increased with the increase of drying air temperature, and the value of activation energy was 62.84 kJ mol−1. The quality of lemongrass plants evaluated by the electrical conductivity test was inversely proportional to the increase in drying air temperature, and the levels of essential oils were higher in dry plants with lower drying air temperatures. The adaptation of the electrical conductivity methodology to lemongrass plants was effective. A period of 33 h of imbibitions of the material in deionized water was necessary to obtain consistent results from leaching of potassium ions. The electrical conductivity can be used as a quality parameter for drying of medicinal plants.

Avaliação das curvas de secagem de guaco (Mikania glomerata Spreng.) em secador de bandejas

This work aimed to evaluate different mathematical models to determine the curve of the drying of Mikania glomerata Spreng. . For the conduction of the experiment, a drier with forced ventilation was used, with 4 trays, using liquefied petroleum gas as heating source. Six drying treatments were carried out, that is, with hot air at 40, 50, 60, 70 and 80oC, as well as drying with air at room temperature. For all the treatments, the drying air speed, through the mass of plants, were kept at, approximately, 0.5 m s-1. For the adjustment of the mathematical models to the experimental data, nonlinear regression analysis was performed through the Quasi-Newton method, using the computational program STATISTICA 6.0®, and the values of the parameters of the models were estimated in function of the temperature of the drying air. But only the model considered by Midilli et al. presented satisfactory adjustment to describe the process of drying Mikania glomerata Spreng., regardless of the temperature of the drying air, while the model of diffusion approximation was suitable for room temperature and hot air at 60oC.

Rendimento extrativo de cumarina de folhas de guaco (Mikania glomerata Sprengel) submetidas a diferentes temperaturas de secagem

The aim of this study was to evaluate the effect of drying on the extraction yield of coumarin from guaco leaves. Six drying treatments were used, being room air, heated air at 40, 50, 60, 70 and 80oC. A tray dryer was used with liquefied petroleum gas (LPG) as heating source. The extraction yield of coumarin, after drying, was compared to the values obtained from the fresh plant (control treatment). Coumarin extraction was carried out by using the heat method, in water bath at 65oC, and identification and quantification were done by means of high performance liquid chromatography (HPLC). Considering the obtained results, the temperature of the drying air at 50oC led to the best result for the extraction yield of coumarin in guaco leaves.

Influência do processo de secagem sobre os principais componentes químicos do óleo essencial de tomilho

Objetivou-se, com este trabalho, avaliar o efeito da temperatura do ar de secagem sobre a qualidade do oleo essencial de folhas de tomilho. Foram empregadas diferentes temperaturas de secagem (30, 40, 50, 60, 70 oC), em um secador com resistencias eletricas. Os componentes quimicos do oleo essencial, depois de realizada a secagem, foram comparados com os valores obtidos na planta in natura (testemunha). Para a extracao do oleo essencial, foi empregado o metodo de extracao com CO2 supercritico. A identificacao dos componentes quimicos do oleo essencial foi realizada por cromatografia gasosa, acoplada ao espectrofotometro de massas (CG-EM) e, para a quantificacao desses componentes, empregou-se o cromatografo a gas, acoplado ao detector por ionizacao de chamas (CG-DIC). Em funcao dos resultados obtidos, recomenda-se ar, a temperatura de 60 oC, para a secagem das folhas de tomilho.

INFLUÊNCIA DA TEMPERATURA DO AR DE SECAGEM SOBRE A COMPOSIÇÃO QUÍMICA DO ÓLEO ESSENCIAL DE MELALEUCA

This study was done to evaluate the influence of drying air temperature on the chemical composition of the essential oil of Melaleuca alternifolia Cheel. Three samples were taken at random from each treatment which were analyzed still fresh, determining the moisture content and chemical composition of the essential oil.The plants were chopped and placed in a fixed-bed dryer and dried with air temperature of 40, 50, 60, 70 and 80 °C. The identification of compounds was done using gas chromatography coupled to mass spectrometry. The major components of essential oil of melaleuca subjected to drying air temperatures of 40, 50, 60, 70 and 80 ° C were within the ISO Standard 4730, which classifies plant as medicinal or not.There was an increase in the levels of terpinen-4-ol and α-terpineol and decrease of α-pinene compared to the control.