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Palavras-chave: hortaliça secagem convectiva Acmella oleracea A B S T R A C TThe aim of this paper was to analyze the drying kinetics, test the Akaike information criterion (AIC) and Schwarz's Bayesian information criterion (BIC) in the selection of models, determine the effective diffusivity and activation energy of the crushed mass of 'jambu' leaves for different conditions of temperature and layer thicknesses. The experiment was carried out at the Food Laboratory of the Brazilian Agricultural Research Corporation (Embrapa) in Macapá-AP. Drying was carried out in air circulation oven with speed of 1.0 m s -1 at various temperatures (60, 70 and 80 ºC) and layer thicknesses (0.005 and 0.010 m). The experimental data were fitted to 11 mathematical models. Coefficient of determination (R²), mean relative error (P), mean estimated error (SE), Chi-square test (χ²), AIC and BIC were the selection criteria for the models. For the effective diffusivity, the Fick's diffusion model was used considering the flat plate geometry. It was found that Midilli and Logarithmic models showed the best fit to the experimental data of drying kinetics. Effective diffusion coefficient increases with increment in the thickness of the material and with the temperature elevation. Activation energy of the material was of 16.61 kJ mol -1 for the thickness of 0.005 m, and 16.97 kJ mol -1 for the thickness of 0.010 m. AIC and BIC can be additionally included to select models of drying.Cinética de secagem da massa triturada de jambu: Difusividade efetiva e energia de ativação R E S U M O Objetivou-se com o presente trabalho analisar a cinética de secagem, testar os critérios da informação de Akaike (AIC) e informação Bayesiano de Schwarz (BIC) para seleção dos modelos, determinar a difusividade efetiva e a energia de ativação de massa triturada de folhas de jambu para diferentes condições de temperatura e espessuras de camada. O experimento foi desenvolvido no Laboratório de Alimentos da Empresa Brasileira de Pesquisa Agropecuária (Embrapa), em Macapá -AP. A secagem foi realizada em estufa de circulação de ar com velocidade de 1,0 m s -1 em diferentes temperaturas (60, 70 e 80 ºC) e espessuras da camada (0,005 e 0,010 m). Aos dados experimentais foram ajustados onze modelos matemáticos. O coeficiente de determinação (R²), erro médio relativo (P), erro médio estimado (SE), teste de Qui-quadrado (χ²), AIC e BIC, foram os critérios de seleção dos modelos. Para a difusividade efetiva utilizou-se o modelo difusivo de Fick para a forma geométrica de placa plana. Constatou-se que os modelos de Midilli e Logaritmo melhor se ajustam aos dados experimentais da cinética de secagem. O coeficiente de difusão efetivo aumentou com o incremento da espessura da camada de material e com a elevação da temperatura. A energia de ativação do material foi de 16,61 kJ mol -1 para a espessura de 0,005 m e de 16,97 kJ mol -1 para a espessura de 0,010 m. Os critérios de AIC e BIC podem ser incluídos adicionalmente para seleção de modelos de secagem.

Jambu, Acmella oleracea (L.), is a low-growing herb plant, with cylindrical, fleshy, decumbent and branched stem varying from 20 to 30 cm in height. It is an abundantly cultivated and consumed vegetable in the northern region of Brazil and usually consumed in preparations of typical foods of the Amazon region. So, this work aimed to compare the chemical composition and physical chemistry of powdered and jambu leaf mass. Acmella oleracea plants were selected, sanitized and their leaves were crushed (without adding water). The mass was dried in an oven with forced air circulation under different conditions of temperature (60, 70 and 80 C) and relative humidity (13.09, 8.14 and 5.45%, respectively), in two layer thicknesses (0.5 and 1.0 cm). The physical, chemical, physicochemical parameters moisture content, water activity, ash, protein, lipids, pH, total titratable acidity and color were analyzed in powdered and fresh leaves. Contrast test was used to evaluate the interaction between the layer thicknesses at 5% level of significance. Considering the contrasts, the parameters total soluble solids, ash, protein and lipids do not differ from those in the fresh sample, demonstrating that these parameters are not modified or degraded with the drying conditions. The pH and color parameters differed from those of the fresh material, due to degradation, which can be linked to the rise in temperature sensitivity. The moisture content and water activity also differed and were reduced, contributing to conservation of the material. Contrast analysis made it possible to conclude that the physicochemical composition did not undergo modifications through the use of drying. In addition, a powdered material with reduced water activity was obtained.

Condiments and culinary supplements are subjected to long-term storage and may undergo physical, chemical, and biological changes that can influence their quality. Thus, the objective of the present study was to analyze the drying kinetics of rose pepper (Schinus terebinthifolius Raddi) fruits in an oven with forced air circulation at different temperatures, namely, 45, 55, 65, and 75°C, and determine the effective diffusion coefficient and activation energy using different mathematical models. Furthermore, the effects of the different drying temperatures were analyzed for external color parameters and yield of essential oil contents by gas chromatography coupled to a mass spectrometer. Of the ten models used for fitting, Thompson’s model was one with the best fitting to represent the drying of rose pepper fruits. The diffusion coefficient increases with the elevation of drying air temperature, described by the Arrhenius equation, with activation energy of 53.579 kJ·mol−1. The color of the fruits decreased in lightness (L ∗ ) with the increase in temperature. Of the thirty-eight terpenes identified, α-pinene and cis-ocimene were the most abundant, with the overall highest yield being found at a drying temperature of 45°C.

Jambu is a vegetable originally from the northern region of Brazil, has bioactive properties, being little explored by other regions, due to its high peresivity. And one of the methods to increase the shelf life of plant products is the removal of water. The objective of this work was to evaluate the drying kinetics of jambu leaf mass. Two treatments were carried out: The mass of fresh jambu leaves and the mass of fresh jambu leaves with the addition of drying foam, both submitted in an oven with forced air circulation at temperatures (50, 60 and 70 °C and thickness of 1.0 cm). The proximate composition of the materials was performed before and after drying. Twelve mathematical models were tested on drying kinetics data and thermodynamic properties were calculated. The parameters of the proximate composition for the mass of leaves and foam after drying were: Moisture content of (2 to 7%), ash content of (13 to 17%), protein content of (22 to 30%), lipids of (0.6 to 4%) and total titratable acidity (0.20 to 0.28%) of tartaric acid. The models that best fit the experimental data to describe the drying kinetics of jambu masses were: Wang & Singh. The use of foam mat presented higher values of effective diffusion coefficient and activation energy and lower values of enthalpy and entropy, reducing the drying time.

The objective of this study was to evaluate the drying kinetics of the mass of jambu leaves and mass of jambu leaves in foam mat at different temperatures (50, 60 and 70 °C and thickness of 1.0 cm). The physicochemical characterization of the materials was performed before and after drying. Twelve different drying models were fitted to the drying kinetics data and the thermodynamic properties were calculated. The physicochemical parameters for the mass of leaves and foam after drying were moisture content from 2 to 7%, ash from 13 to 17%, protein content from 22 to 30%, lipids from 0.6 to 4% and total titratable acidity from 0.20 to 0.28% of tartaric acid. Wang & Singh and Midilli models were recommended for describing the drying kinetics. The use of foam mat promoted higher values of effective diffusion coefficient and activation energy and lower values of enthalpy and entropy, thus enhancing the reduction of drying time.

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The growing global demand for food has required innovations in the techniques of processing and conservation of food raw materials. An alternative to expand food availability is to apply technologies aimed at preserving and increasing the durability of materials, in addition to significantly reducing waste. Currently, the food industry has stood out with the application of drying techniques for better conservation and marketing. This review presents studies carried out in the last decade on developments in new drying technologies, the improvement of techniques and their advantages and disadvantages. Thus, the aim is to show the relevance of this food processing technique and its advances regarding the techniques applied in food, given the complexity of the composition of food raw materials.