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.

Abstract Araticum (Annona crassiflora) fruits have relevant characteristics for industrialization, a characteristic aroma and a slightly acidic flavor, with relevant amounts of vitamins A, C, B1 and B2. The objective of this study was to fit different mathematical models to the experimental data, evaluate the effective diffusion coefficient and determine the activation energy for the araticum epicarp subjected to different drying conditions. The epicarps of araticum fruits were dried at temperatures of 40, 50, 60 and 70 °C. Midilli, Logarithmic and Two Terms models can be used to represent the drying of araticum epicarp, and the Two Terms model was selected according to the Akaike Information Criterion (AIC) and Schwarz’s Bayesian Information Criterion (BIC). The linear model satisfactorily represented the effective diffusion coefficient as a function of drying temperature. In the evaluation of enthalpy, entropy and Gibbs free energy, both enthalpy and entropy tend to decrease when temperature increases. The higher the temperature used for drying of araticum epicarp, the lower the value of diffusivity, i.e., the lower the resistance to water removal.

Abstract The objective of this study was to evaluate the influence of drying treatment on the characteristics physical, chemical, technological properties and bioactive of turmeric flour. The flour was obtained from the drying of rhizomes in a forced air circulation oven at temperatures of 45, 55, 65 and 75 °C. The analyzes performed were: pH, instrumental color, microstructure, granulometry, water and oil absorption indices, water solubility indices, and antioxidant activity. The characteristics of the flours significantly affected were moisture, protein, lipid and ash contents. The antioxidant capacity with the DPPH radical, for flour at the drying temperature of 45 °C, presented the highest value 36.55 Mmol Trolox g-1, and 7686.32 Mmol FeSO4 g-1 the FRAP radical at 65 °C.The phenolic content varied according to the solvent applied to obtain the extract, the mean values of total phenolic compounds for each temperature were: 0.419, 0.332, 0.316, 0.283 mg GAEa 100 g-1for temperatures 45, 55, 65 and 75°C respectively. Water solubility index (WSI) and oil absorption index ranged from 12.45 g g-1 to 11.78 g g-1 and from 2.54 g g-1 to 2.49 g g-1, respectively, for temperatures of 45 °C and 75 °C. The results of the present study indicated that temperature influences the physicochemical and technological properties of turmeric flour.

Abstract The cagaita is a native fruit from Brazilian Cerrado region. Among conservation techniques and to increase shelf life of the fruit, foam bed drying becomes ideal. This study adjusted mathematic models of foam drying of the cagaita pulp at different temperatures to determine the net diffusion coefficient and the activation energy of this process. As the foam layer drying has a shorter drying time due to the greater exposure of the surface area to the air, it allows the application of lower dehydration temperatures, so it used 40, 50, 60 and 70 °C, the data observed were better fitted to the Midilli model. The net diffusion coefficient increased with temperature and the activation energy was 25.368 kJ mol-1.

ABSTRACT Study of the mechanical characteristics of agricultural products is crucial to the development of equipment that can achieve the maximum efficiency without compromising the final product quality. Seeds crack and break when exposed to stresses that exceed their resistance to rupture. In this study, we aim to assess the mechanical properties of saccharine sorghum (Sorghum bicolor L. Moench) seeds at different moisture contents. The seeds were harvested in the municipality of Santa Helena - GO, Brazil and indicated an initial moisture content of 0.307 (d.b.). For each moisture content obtained (0.307, 0.258, 0.212, 0.170, 0.130, and 0.093 d.b.), samples were homogenized and subsequently analyzed. Compressive tests were performed through uniaxial tests in a sample of 15 seeds for each moisture content. In these tests, the "TA Hdi Texture Analyzer" universal testing machine was used, with a 250-N compression load cell. Our results indicated that the compressive force required to deform saccharine sorghum seeds decreased with increasing moisture content, whereas values of proportional modulus of deformity increased with both reduced moisture content and deformation. In addition, the reduction in moisture content caused an increase in the force required to rupture the seeds.

RESUMEN El estudio de las características mecánicas de los productos agrícolas es importante para que los equipos puedan desarrollarse y lograr la máxima eficiencia sin comprometer la calidad final de los alimentos. Las grietas y roturas de las semillas se producen cuando están expuestas a tensiones que exceden la resistencia del material. El objetivo de este trabajo fue evaluar algunas pro piedades mecánicas de las semillas de sorgo de sacarina (Sorghum bicolor L. Moench) con diferentes contenidos de humedad. Las semillas se cosecharon en el municipio de Santa Helena - GO, Brasil, y presentaron un contenido de humedad inicial de 0.307 base seca (b.s.). Para cada contenido de humedad obtenido (0,307; 0,258; 0,212; 0,170; 0,130 y 0,093 b.s.), las muestras fueron homogeneizadas y luego analizadas. Las pruebas de compresión uniaxial se realizaron en una muestra de 15 semillas para cada contenido de humedad. Para esta determinación se utilizó la máquina de prueba universal Analizador de textura TA Hdi, con una celda de carga de compresión de 250 N. Nuestros resultados evidenciaron que la fuerza de compresión necesaria para deformar las semillas de sorgo disminuyó con el aumento del contenido de humedad, mientras que los valores del módulo de deformidad proporcional se incrementaron con la reducción tanto del contenido de humedad como de la deformación. Además, la reducción del contenido de humedad aumentó la fuerza requerida para romper las semillas.

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.

RESUMO: Neste trabalho objetivou-se verificar a influência do teor de água nos valores da força máxima de compressão, módulo proporcional de deformidade, coeficientes elásticos d, e, f, além dos valores da tangente e secante máximas nos grãos de crambe (Crambe abyssinica Hochst), submetidos à compressão na posição natural de repouso. Os grãos de crambe, utilizados com teores de água entre 0,1547 e 0,0482 (decimal b.s.), foram secos nas temperaturas de 40°C e comprimidos uniaxialmente entre duas placas paralelas, na posição natural de repouso, cuja redução do teor de água ao longo da secagem foi acompanhada pelo método gravimétrico (perda de massa). A força de compressão necessária para deformar os grãos de crambe diminui com o aumento do teor de água. O módulo proporcional de deformidade aumenta com a redução da deformação, obtendo-se valores entre 0,09 e 0,27 (x 102MPa), em que o modelo sigmoidal, descrito por meio da série de Taylor, representa adequadamente a resistência dos grãos de crambe à compressão na posição natural de repouso, para os teores de água menores que 0,0813 (b.s.)

ABSTRACT: This study aimed to verify the influence of moisture content on the values of maximum compressive strength, proportional deformity modulus, elastic coefficients d, e, and f beyond the tangent values, and maximum grain drying of crambe (Crambe abyssinica Hochst) under compression in natural resting position. Crambe grains with moisture contents ranging from 0.1547 to 0.0482 decimal db were dried at 40°C and uniaxially compressed between two parallel plates in the natural rest position. The gravimetric method was used to monitor reduction in moisture content during drying (weight loss). It was concluded that the compression force required to deform the crambe grains decreases as the moisture content increases. The proportional deformity modulus increases as the deformation decreases, yielding values between (0.09-0.27)×102MPa. Sigmoidal model described by Taylor series adequately represents the compression resistance of crambe grains in the natural rest position with moisture content lower than 0.0813db.

RESUMO. O objetivo no presente trabalho foi determinar e avaliar as propriedades termodinâmicas para diferentes teores de água de equilíbrio dos frutos de crambe. Para obter os dados experimentais utilizou-se o método dinâmico-gravimétrico. Foram utilizados frutos de crambe, com teor de água inicial de, aproximadamente, 26 % b.s. (base seca). A dessorção do produto em camada delgada foi realizada para diferentes condições controladas de temperatura (25, 30, 35, 40 e 45°C) e atividades de água entre 0,10 e 0,89, até que o produto atingisse seu teor de água de equilíbrio com a condição do ar especificada. Conclui-se que as propriedades termodinâmicas dos frutos de crambe são influenciadas pelas temperaturas e pelos teores de água. A teoria da isocinética é válida para o processo de dessorção, sendo este controlado pela entalpia. A energia livre de Gibbs é positiva para todas as temperaturas estudadas, indicando que a dessorção da água é um processo não espontâneo.

ABSTRACT. This study aimed to determine and evaluate the thermodynamic properties of crambe fruit at different equilibrium moisture contents. The dynamic-gravimetric method was used to collect experimental data. Crambe fruits with an initial moisture content of approximately 26% db (dry basis) were used. The thin-layer desorption of the product was conducted at different controlled temperatures (25, 30, 35, 40, and 45°C) and at water activity levels ranging from 0.10 to 0.89 until the product reached the equilibrium moisture content at the specified air condition. In conclusion, the thermodynamic properties of crambe fruit are affected by temperature and moisture content. The isokinetic theory is valid for the desorption process, which is controlled by enthalpy, and the Gibbs free energy is positive at all of the tested temperatures, which indicates that water desorption is not a spontaneous process.

RESUMODiante da importância do conhecimento da higroscopicidade e do calor isostérico para as operações de secagem e armazenamento, objetivou-se neste trabalho determinar as isotermas de dessorção de sementes de Buchenavia capitata (Vahl) Eichler, bem como ajustar diferentes modelos matemáticos aos dados experimentais, selecionando aquele que melhor representa o fenômeno e, assim, utilizá-lo para determinar o calor isostérico de dessorção. Para obtenção do teor de água de equilíbrio higroscópico utilizaram-se as sementes de B. capitata com teor de água inicial de 13,16 ± 0,17% base seca (b.s.). Para obtenção das isotermas de dessorção das sementes, utilizou-se o método estático indireto, sendo a atividade de água (aw) determinada por meio do equipamento Hygropalm Model Aw 1. Para o controle da temperatura utilizou-se uma câmara tipo B.O.D., regulada a 10; 20; 30 e 40 °C. Aos dados experimentais foram ajustados os modelos matemáticos frequentemente utilizados para representação da higroscopicidade de produtos vegetais. O teor de água de equilíbrio higroscópico das sementes de Buchenavia capitata (Vahl) Eichler é diretamente proporcional à atividade de água e decresce com o aumento de temperatura para um mesmo valor de umidade relativa de equilíbrio. O modelo matemático de Copace é o que melhor representa a higroscopicidade de sementes de B. capitata nas temperaturas e nas atividades de água estudadas. O calor isostérico de sementes de B. capitata aumenta com a diminuição do teor de água de equilíbrio, sendo necessária maior quantidade de energia para retirar a água.

ABSTRACTGiven the importance of understanding hygroscopicity and isosteric heat in drying and storage operations, the aim of this work was to determine desorption isotherms in seeds of Buchenavia capitata (Vahl) Eichler, and to fit different mathematical models to the experimental data, selecting the one that best represents the phenomenon, and using it to determine the isosteric heat of desorption. To obtain the hygroscopic equilibrium moisture content, seeds of B. capitata with an initial moisture content of 13.16 ± 0.17% db (dry basis) were used. To obtain the desorption isotherms of the seeds, the indirect static method was employed, with the water activity (aw) being determined by a Model Aw 1 Hygropalm. The temperature was controlled by means of a BOD chamber set at 10, 20, 30 and 40°C. Mathematical models frequently used to represent the hygroscopicity of plant products were adjusted to the experimental data. The hygroscopic equilibrium moisture content of seeds of Buchenavia capitata (Vahl) Eichler is directly proportional to water activity, and decreases with increasing temperature for a given value of equilibrium relative humidity. The Copace mathematical model best represents hygroscopicity for seeds of B. capitata at the temperatures and water activity under study. Isosteric heat in seeds of B. capitata increases with decreases in the equilibrium moisture content, a greater amount of energy being required to remove the water.

O objetivo do presente trabalho foi determinar as propriedades termodinâmicas do processo de sorção de água em sementes de nabo forrageiro. O teor de água de equilíbrio das sementes de nabo forrageiro foi determinado pelo método dinâmico-gravimétrico para diferentes valores de temperatura e atividade de água. De acordo com os resultados encontrados, observou-se que com o incremento do teor de água ocorre aumento da energia necessária para a evaporação da água nas sementes de nabo forrageiro, sendo que os valores do calor isostérico integral de dessorção, na faixa de teor de água de 3,33 a 11,30 (% b.s.), variam de 4.222,70 a 2.870,34 kJ kg-1. Com a elevação do teor de água de equilíbrio há um aumento da entropia diferencial e da energia livre de Gibbs que apresenta valores positivos demonstrando não-espontaneidade no processo de dessorção nas sementes. A teoria de compensação entalpia-entropia pode ser satisfatoriamente aplicada ao fenômeno de sorção, sendo o processo de dessorção da água das sementes de nabo forrageiro controlados pela entalpia.

The purpose of this study was to determine the thermodynamic properties of the process of water sorption in forage turnip seeds. The equilibrium moisture content of forage turnip seeds was determined by the gravimetric-dynamic method for different values of temperature and water activity. According to the results, increasing the moisture content increases the energy required for the evaporation of water in forage turnip seeds, and the values of integral isosteric heat of desorption, within the moisture content range of 3.33 to 11.30 (% d.b.), varies from 4,222.70 to 2,870.34 kJ kg-1. With the elevation in the equilibrium moisture content, there is an increase in differential entropy and Gibbs free energy, which has positive values, demonstrating non-spontaneity in the process of desorption in the seeds. The theory of enthalpy-entropy compensation can be satisfactorily applied to the sorption phenomenon, and the process of water desorption of forage turnip seeds is controlled by enthalpy.

O estudo das propriedades termodinâmicas propor-ciona o conhecimento da afinidade do sorvente pela água e da espontaneidade do processo de sorção, sendo importante para projetar equipamentos de secagem. Este trabalho visou a determinar e avaliar as propriedades termodinâmicas, para diferentes teores de água de equilíbrio em grãos de milho, utilizando-se o método estático indireto. O experimento foi desenvolvido em Rio Verde (GO), utilizando-se grãos de milho da cultivar AG 7088, com teor inicial de água de 23,3% (base seca - b.s.), os quais foram submetidos a secagem (40ºC), até atingirem teor de água de 14,4% (b.s.). Concluiu-se que as propriedades termodinâmicas foram influenciadas pelo teor de água, o calor isostérico integral de dessorção aumentou com o decréscimo do teor de água de equilíbrio, o processo de dessorção do milho da cultivar AG 7088 foi controlado pela entalpia e a energia livre de Gibbs foi positiva para as temperaturas estudadas, com aumento ao longo do processo de dessorção, demonstrando ser um processo não espontâneo.

The study of thermodynamic properties provides knowledge on the sorbent affinity for water and spontaneity of the sorption process, being important to design drying equipments. This study aimed at determining and evaluating the thermodynamic properties of different equilibrium moisture contents in maize grains, by using the indirect static method. The experiment was conducted in Rio Verde, Goiás State, Brazil, with maize grains (AG 7088 cultivar) presenting an initial moisture content of 23.3% (dry basis - d.b.), which were dried (40ºC) to achieve the moisture content of 14.4% (d.b.). It was observed that the thermodynamic properties were influenced by moisture content, the integral isosteric heat of desorption increased with the decrease in the equilibrium moisture content, the desorption process of the AG 7088 maize cultivar was controlled by enthalpy and the Gibbs free energy was positive for the temperatures evaluated, increasing along the desorption process, showing to be a non-spontaneous process.