Navegando por Autor "Corrêa, Paulo Cesar"
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Item Avaliação de dano mecânico em sementes de feijão por meio de condutividade elétrica(Revista Brasileira de Engenharia Agrícola e Ambiental, 1999-01) Andrade, Ednilton Tavares de; Corrêa, Paulo Cesar; Martins, José Helvecio; Alvarenga, Eveline MantovaniEste trabalho foi realizado com o intuito de se avaliar danos mecânicos em sementes de feijão ( Phaseolus vulgaris L.) variedade Ouro Negro 1992, por meio de condutividade elétrica da solução contendo as sementes danificadas devido ao choque mecânico controlado, com utilização de três níveis de velocidade de choque. Para se comparar a queda de qualidade devido ao choque mecânico, foram utilizados também o teste-padrão de germinação e a avaliação visual dos danos mecânicos, cujos resultados permitiram concluir que a utilização da condutividade elétrica da solução contendo as sementes pode ser correlacionada com o índice de danos mecânicos podendo, portanto, ser utilizada para avaliar danos mecânicos em sementes.Item Comparative study of the physical and chemical characteristics of coffee and sensorial analysis by principal components(Food Analytical Methods, 2015-05) Corrêa, Paulo Cesar; Reis, Efraim Lázaro; Oliveira, Ana Paula Lelis Rodrigues de; Oliveira, Gabriel Henrique Horta deThe objective of this work is to compare properties of coffee under different post-harvest processing with its sensorial characteristics by principal component analysis (PCA) features, in order to help it, making it less subjective. Coffee fruits were harvested, and a part of them had their mucilage removed and, then, taken to the Laboratory of Physical Properties in the Federal University of Viçosa, Brazil. The coffee without mucilage was dried at temperatures of 40, 50, and 60 °C. Cherry coffee was dried at three different temperatures (40, 50 and 60 ºC); however, when subjected to 40 °C, coffee quality suffered an addition of 0, 10, 20, and 30 % of green fruits. The samples were subjected to analysis of color, electric conductivity, density, thousand grain masses, gas chromatography, and sensorial analysis in the beginning and at every 3 months of storage for 1 year. Through the PCA, it was possible to differentiate samples that were submitted to post-harvest processing. After 12 months of storage, it has been noted a similarity between groups differentiated by PCA of chemical and physical characteristics of coffee and groups differentiated by PCA of sensorial analysis. Compatibility between characterization techniques for PCA was observed, making the technique effective in helping the cup testing.Item Contração volumétrica e forma dos frutos de mamona durante a secagem(Acta Scientiarum. Agronomy, 2011-01) Goneli, André Luís Duarte; Corrêa, Paulo Cesar; Magalhães, Felipe Elia de Almeida; Baptestini, Fernanda MachadoO objetivo do presente trabalho foi avaliar o efeito da variação do teor de água na contração volumétrica, dimensões características e forma dos frutos de mamona durante a secagem. Foram utilizados frutos colhidos com teor de água de 2,50 (b.s.), secos à temperatura de 40ºC até o teor final de 0,11 (b.s.). O tamanho dos frutos foi determinado por meio da variação do volume e a forma foi analisada pela esfericidade e circularidade. A contração volumétrica dos frutos foi determinada pela relação entre o volume em cada teor de água e o volume inicial. Com base nos resultados, concluiu-se que a forma dos frutos de mamona é influenciada pela redução do teor de água, promovendo redução da esfericidade e circularidade. As dimensões características (comprimento, largura e espessura) e o diâmetro geométrico médio dos frutos sofrem redução de suas magnitudes com a redução do teor de água. A redução do teor de água influencia a contração volumétrica unitária e da massa dos frutos de mamona, provocando redução de seus valores em 46,0 e 63,0%, respectivamente. O modelo polinomial, dentre aqueles testados, foi o que melhor representou o fenômeno da contração volumétrica da massa e unitária dos frutos de mamona.Item Developing predictive models for determining physical properties of coffee beans during the roasting process(Industrial Crops and Products, 2018-02) Vanegas, Jaime Daniel Bustos; Corrêa, Paulo Cesar; Martins, Márcio Arêdes; Baptestini, Fernanda Machado; Campos, Renata Cássia; Oliveira, Gabriel Henrique Horta de; Nunes, Eduardo Henrique MartinsThis study aims to evaluate and model the variation in the physical properties of coffee beans in isothermal roasting conditions, providing mathematical expressions that can be used for heat and mass transfer models for coffee roasting. Arabica coffee beans were studied with an initial moisture content of 0.129 kgw kgdm−1 and roasted in a direct gas burning roaster. Five temperatures were set inside the cylinder (200, 220, 240, 260 and 280 °C). The beans were roasted uniformly by suspension in the center of the drum. A thermocouple recorded the temperature every 5 s. X-ray microtomography was used to analyze the evolution of the internal matrix during the roasting process. The moisture content and physical properties (volume, surface area, and density) of each coffee bean were evaluated every 20 s. Empirical models were fitted to represent the physical properties as a function of the moisture content. It was observed that the volumetric expansion is isotropic at roasting temperatures above 220 °C. The final bean volume can reach up to 1.8 times the initial volume. The bean density varied linearly with the moisture content, presenting a larger drop at a higher roasting temperature.Item Efeito de antioxidantes sobre o escurecimento de batatas baroa minimamente processadas(Engenharia na Agricultura, 2013-12-12) Fernandes, Lara Santana; Corrêa, Paulo Cesar; Finger, Fernando Luiz; Junqueira, Mateus da Silva; Fonseca, Kelem SilvaObjetivou-se com este trabalho avaliar o efeito de diferentes concentrações dos antioxidantes ácido ascórbico e ácido cítrico sobre o escurecimento de batatas baroa minimamente processadas. As raízes foram selecionadas, lavadas com detergente e enxaguadas em água corrente. Em seguida, foram sanitizadas, descascadas, cortadas em fatias de 1cm de espessura e novamente sanitizadas com posterior enxágue. Logo após, as rodelas foram imersas nos seguintes tratamentos: água gelada; solução de ácido ascórbico 1% + ácido cítrico 1%; solução de ácido ascórbico 2% + ácido cítrico 2% e solução de ácido ascórbico 3% + ácido cítrico 3%. As rodelas foram centrifugadas, acondicionadas em embalagens de polipropileno e mantidas a 5 ± 2 oC e 90 ± 5% de umidade relativa, durante um período de oito dias. Para a avaliação da perda de massa, o experimento foi instalado em esquema fatorial 4 x 9 (4 tratamentos aos 0, 1, 2, 3, 4, 5, 6, 7 e 8 dias) no delineamento inteiramente casualizado com quatro repetições. Para as análises de cor, pH e teor de sólidos solúveis foi utilizado um esquema fatorial 4 x 5 (4 tratamentos aos 0, 2, 4, 6 e 8 dias) com quatro repetições. Os dados foram submetidos à metodologia de superfície de resposta. As batatas apresentaram melhor qualidade com o tratamento 3% ácido ascórbico + 3% ácido cítrico, chegando ao final do armazenamento com menor perda da coloração amarela.Item Effects of the mechanical damage on the water absorption process by corn kernel(Food Science and Technology, 2013-04) Botelho, Fernando Mendes; Corrêa, Paulo Cesar; Martins, Márcio Arêdes; Botelho, Sílvia de Carvalho Campos; Oliveira, Gabriel Henrique Horta deThe purpose of this study was to investigate and model the water absorption process by corn kernels with different levels of mechanical damage Corn kernels of AG 1510 variety with moisture content of 14.2 (% d.b.) were used. Different mechanical damage levels were indirectly evaluated by electrical conductivity measurements. The absorption process was based on the industrial corn wet milling process, in which the product was soaked with a 0.2% sulfur dioxide (SO2) solution and 0.55% lactic acid (C3H6O3) in distilled water, under controlled temperatures of 40, 50, 60, and 70 ºC and different mechanical damage levels. The Peleg model was used for the analysis and modeling of water absorption process. The conclusion is that the structural changes caused by the mechanical damage to the corn kernels influenced the initial rates of water absorption, which were higher for the most damaged kernels, and they also changed the equilibrium moisture contents of the kernels. The Peleg model was well adjusted to the experimental data presenting satisfactory values for the analyzed statistic parameters for all temperatures regardless of the damage level of the corn kernels.Item Estudo da difusão de umidade em grãos de trigo durante a secagem(Food Science and Technology, 2007-01) Gonelli, André Luís Duarte; Corrêa, Paulo Cesar; Resende, Osvaldo; Reis Neto, Stelito Assis dosO objetivo do presente trabalho foi ajustar o modelo da difusão líquida às curvas de secagem do trigo considerando a contração volumétrica do grão e determinar os coeficientes de difusão para diversas condições controladas de temperatura e umidade relativa. Foram utilizados grãos de trigo, com teor de água inicial de 0,32 b.s. A secagem do produto foi realizada para diferentes condições controladas de temperatura, entre 25 e 55 °C, e umidade relativa de 55 ± 1%. A contração volumétrica do grão foi determinada pela relação entre o volume para cada teor de água e o volume inicial. Com base nos resultados obtidos, conclui-se que o modelo da difusão líquida representa satisfatoriamente a cinética de secagem do trigo para as diversas condições de ar experimentadas, não tendo sido considerado o efeito da contração volumétrica dos grãos. O coeficiente de difusão aumenta com a elevação da temperatura do ar, apresentando valores de 8,6775 x 10-11 e 42,8743 x 10-11 m2.s-1 para a faixa de temperatura estudada e considerando a contração volumétrica. A relação entre o coeficiente de difusão e a temperatura pode ser descrita pela expressão de Arrhenius, que apresenta uma energia de ativação para a difusão líquida nos grãos de trigo de 42,00 kJ.mol-1.Item Evaluation of thermodynamic properties using GAB model to describe the desorption process of cocoa beans(International Journal of Food Science and Technology, 2011-07-26) Oliveira, Gabriel Henrique Horta de; Corrêa, Paulo Cesar; Santos, Emı́lio de Souza; Treto, Pedro Casanova; Diniz, Mayra Darliane Martins SilvaThe desorption isotherms and thermodynamic properties of cocoa beans were obtained during the drying process of this product. The isotherms were determined by dynamic method for various temperature (25, 35,45 and 55 C) and relative humidity (RH) conditions (30, 40, 50, 60, 70 and 80%). Equilibrium moisture content data were correlated by the Guggenheim–Anderson–de Boer (GAB) model, which presented good fit to the data, according to statistical procedures. Equilibrium moisture content ranged from 5.90 to 16.67 d.b.; it increased with an increment in the RH and decreased with increased temperature at a constant RH.Enthalpy values for each model coefficient were encountered, ranging from )90.05 to 545.96 kJ kg )1 . The integral isosteric heat of desorption and differential entropy increased with decreased equilibrium moisture content, a tendency also found for Gibbs free energy.Item Heat and mass transfer coefficients and modeling of infrared drying of banana slices(Revista Ceres, 2017-07-12) Baptestini, Fernanda Machado; Corrêa, Paulo Cesar; Oliveira, Gabriel Henrique Horta de; Botelho, Fernando Mendes; Oliveira, Ana Paula Lelis Rodrigues deBanana is one of the most consumed fruits in the world, having a large part of its production performed in tropical countries. This product possesses a wide range of vitamins and minerals, being an important component of the alimentation worldwide. However, the shelf life of bananas is short, thus requiring procedures to prevent the quality loss and increase the shelf life. One of these procedures widely used is drying. This work aimed to study the infrared drying process of banana slices (cv. Prata) and determine the heat and mass transfer coefficients of this process. In addition, effective diffusion coefficient and relationship between ripening stages of banana and drying were obtained. Banana slices at four different ripening stages were dried using a dryer with infrared heating source with four different temperatures (65, 75, 85, and 95 ºC). Midilli model was the one that best represented infrared drying of banana slices. Heat and mass transfer coefficients varied, respectively, between 46.84 and 70.54 W m-2 K-1 and 0.040 to 0.0632 m s-1 for temperature range, at the different ripening stages. Effective diffusion coefficient ranged from 1.96 to 3.59 × 10-15 m² s-1. Activation energy encountered were 16.392, 29.531, 23.194, and 25.206 kJ mol-1 for 2nd, 3rd, 5th, and 7th ripening stages, respectively. Ripening stages did not affect the infrared drying of bananas.Item Influence of the type of packaging on textural properties of minimally processed yellow Peruvian roots(Revista Ceres, 2016-05-10) Fernandes, Lara Santana; Corrêa, Paulo Cesar; Junqueira, Mateus da Silva; Finger, Fernando Luiz; Cecon, Paulo RobertoThe textural properties of minimally processed products indicate its quality, and the package is fundamental to maintain the conservation of these foods. The aim of this study was to evaluate texture alterations that occur during the storage period of minimally processed yellow Peruvian roots, using texture profile analysis (TPA) and relaxation, in function of four types of plastic packaging, combined to refrigeration. The roots were selected, sanitized, peeled and sliced. The processing continued with final sanitization, rinsing and immersion in ascorbic and citric acid solution. The slices were centrifuged and packed in expanded polystyrene trays covered with PVC film, and in high-density polyethylene bags (HDPE), polypropylene bags (PP) and multilayer polyolefin bags for vacuum, and stored at 5 ± 2 ºC and 90 ± 5% relative humidity during 12 days. For the TPA, the parameters of interest were hardness and adhesiveness, automatically calculated from the force curves (F) x time (s). For modeling the relaxation process, the generalized Maxwell model was used. The slices packed in PP and vacuum showed higher hardness and normalized force in the balance (0.7502 and 0.7580, respectively), indicating that they were more elastic, better preserving the quality during storage than slices packed in other packaging.Item Isotermas de dessorção de sementes de beterraba(Engenharia na Agricultura, 2016-03-31) Corrêa, Paulo Cesar; Oliveira, Gabriel Henrique Horta de; Oliveira, Ana Paula Lelis Rodrigues de; Goneli, André Luis Duarte; Botelho, Fernando MendesAlterações físicas e químicas de produtos agrícolas podem ocorrer durante o armazenamento, levando à perdas quantitativas e qualitativas. Portanto, o conhecimento acerca da relação entre o produto, a temperatura (T) e a umidade relativa (UR) do ambiente é necessário para diminuir possíveis alterações. Dito isto, este trabalho objetivou determinar o modelo matemático mais adequado para predizer o teor de água de equilíbrio (Xeq) de sementes de beterraba, cv. “Chata do Egito”, em diferentes T e UR. Xeq foi alcançado por meio do método estático, utilizando soluções salinas saturadas, com valores de UR entre 11 e 96 %. Sementes foram colocadas no interior de dessecadores contendo as soluções salinas, posteriormente armazenadas em câmaras BOD em diferentes T (10; 20; 30; 40 e 50 ºC). Xeq foi obtido quando a variação entre três pesagens consecutivas fosse igual ou menor a 0,01 g. O teor de água foi determinado pelo método gravimétrico usando estufa a 105 ± 1°C até a massa constante. Cinco modelos matemáticos (Chung Pfost, Copace, Halsey Modificado, Henderson e Henderson Modificado) foram ajustados aos dados experimentais de Xeq. O modelo mais adequado foi escolhido considerando a magnitude do erro médio relativo (MRE), desvio padrão da estimativa (SE) e análise de resíduos. O modelo de Chung-Pfost foi o que mais se ajustou aos dados experimentais, apresentando valores de 8,04 % e 0,62 % b.s. de MRE e SE, respectivamente.Item Kinetic modeling of water sorption by roasted and ground coffee(Acta Scientiarum. Agronomy, 2016-09-20) Baptestini, Fernanda Machado; Corrêa, Paulo Cesar; Oliveira, Gabriel Henrique Horta de; Cecon, Paulo Roberto; Soares, Nilda de Fátima FerreiraThe objective of this study was to model the kinetics of water sorption in roasted and ground coffee. Crude Arabica coffee beans with an initial moisture content of 0.1234 kgwkgdm-1 were used. These beans were roasted to a medium roast level (SCCA # 55) and ground at three particle sizes: coarse (1.19 mm), medium (0.84 mm) and fine (0.59 mm). To obtain the water sorption isotherms and the isosteric heat, different conditions of temperature and relative humidity were analyzed using the dynamic method at 25ºC (0.50, 0.60, 0.70, and 0.80 of RH) and 30°C (0.30, 0.40, 0.50, 0.60, 0.70, and 0.80 of RH) and using the static method at 25ºC (0.332 and 0.438 of RH). The GAB model best represented the hygroscopic equilibrium of roasted coffee at every particle size. Isosteric heat of sorption for the fine particle size increased with increments of equilibrium moisture content, indicating a strong bond energy between water molecules and the product components. The Gibbs free energy decreased with the increase in equilibrium moisture content and with temperature.Item Mapping the potential beverage quality of coffee produced in the Zona da Mata, Minas Gerais, Brazil(Journal of the Science of Food and Agriculture, 2015-11-12) Queiroz, Daniel Marçal de; Silva, Samuel de Assis; Ferreira, Williams Pinto Marques; Corrêa, Paulo Cesar; Rufino, José Luis dos SantosDetailed knowledge of coffee production systems enables optimization of crop management, harvesting and post‐harvest techniques. In this study, coffee quality is mapped as a function of coffee variety, altitude and terrain aspect attributes. The work was performed in the Zona da Mata, Minas Gerais, Brazil. A large range of coffee quality grades was observed for the Red Catuai variety. For the Yellow Catuai variety, no quality grades lower than 70 were observed. Regarding the terrain aspect, samples from the southeast‐facing slope (SEFS) and the northwest‐facing slope (NWFS) exhibited distinct behaviors. The SEFS samples had a greater range of quality grades than did the NWFS samples. The highest grade was obtained from an NWFS point. The lowest quality values and the largest range of grades were observed at lower altitudes. The extracts from the highest‐altitude samples did not produce any low‐quality coffee. The production site's position and altitude are the primary variables that influenced the coffee quality. The study area has micro‐regions with grades ranging from 80 to 94. These areas have the potential for producing specialty coffees. © 2015 Society of Chemical IndustryItem Mathematical modeling of dehydration of 'Fuji' and 'Gala' apples slices using infrared(Food Science and Technology, 2010-06-18) Santos, Emílio de Souza; Corrêa, Paulo Cesar; Baptestini, Fernanda Machado; Botelho, Fernando Mendes; Magalhães, Felipe Elia de AlmeidaThe objective of this work was to determine and model the infrared dehydration curves of apple slices - Fuji and Gala varieties. The slices were dehydrated until constant mass, in a prototype dryer with infrared heating source. The applied temperatures ranged from 50 to 100 °C. Due to the physical characteristics of the product, the dehydration curve was divided in two periods, constant and falling, separated by the critical moisture content. A linear model was used to describe the constant dehydration period. Empirical models traditionally used to model the drying behavior of agricultural products were fitted to the experimental data of the falling dehydration period. Critical moisture contents of 2.811 and 3.103 kgw kgs^-1 were observed for the Fuji and Gala varieties, respectively. Based on the results, it was concluded that the constant dehydration rates presented a direct relationship with the temperature; thus, it was possible to fit a model that describes the moisture content variation in function of time and temperature. Among the tested models, which describe the falling dehydration period, the model proposed by Midilli presented the best fit for all studied conditions.Item Mathematical modeling of the drying process of corn ears(Acta Scientiarum. Agronomy, 2011-10) Corrêa, Paulo Cesar; Botelho, Fernando Mendes; Oliveira, Gabriel Henrique Horta; Goneli, André Luis Duarte; Resende, Osvaldo; Campos, Sílvia de CarvalhoThe objective of this work was to study and model the drying process of corn ears at different air temperatures. Thermodynamic properties associated with the drying process of this product were also determined. Corn ears with initial moisture content of 0.45 dry basis (kgw kgdm-1) were dried until they reached a final moisture content of 0.12 (kgw kgdm-1) at temperatures of 45, 55 and 65°C. Traditional models used to describe the drying process of several agricultural products were employed to fit the observed data of the drying process of corn ears. The effective diffusion coefficient (Def) was determined by means of an analytical solution of Fick's second law. It was concluded that the Logarithmic model was the one that best fit the observed data representing the drying process. Def values increased with temperature increases, ranging from 5.490 x 10-10 to 1.163 x 10-9 m2 s-1. Based on the dependence of the drying constant of the Logarithmic model with temperature, thermodynamic properties were determined, concluding that the drying kinetics variation is dependent on the energy contributions of the surrounding environment.Item Modelagem matemática da secagem dos frutos de amendoim em camada delgada(Revista Ciência Agronômica, 2017-07) Araujo, Willian Dias; Goneli, André Luís Duarte; Corrêa, Paulo Cesar; Hartmann Filho, Cesar Pedro; Martins, Elton Aparecido SiqueiraEste trabalho teve por objetivo ajustar modelos matemáticos aos dados experimentais da secagem dos frutos de amendoim em camada delgada, submetidos a diferentes temperaturas do ar de secagem. Foram utilizados frutos de amendoim da cultivar IAC 505. Os frutos de amendoim foram submetidos à secagem em estufa de ventilação forçada com diferentes níveis de temperatura (40; 50; 60 e 70 ºC). Aos dados experimentais foram ajustados dez modelos matemáticos tradicionalmente utilizados para representação da cinética de secagem em camada delgada. Baseado nos resultados encontrados, conclui-se que dentre os modelos ajustados aos dados experimentais, o modelo de Page foi o escolhido para representar o fenômeno de secagem em camada delgada dos frutos de amendoim. O coeficiente de difusão efetivo aumenta com a elevação da temperatura, e a sua relação com a temperatura de secagem pode ser descrita pela equação de Arrhenius. As propriedades termodinâmicas entalpia e entropia tiveram seus valores reduzidos com aumento da temperatura do ar de secagem, enquanto que os valores da energia livre de Gibbs aumentam com o aumento da temperatura.Item Modelagem matemática e determinação das propriedades termodinâmicas do café (Coffea arabica L.) durante o processo de secagem(Revista Ceres, 2010-07) Corrêa, Paulo Cesar; Oliveira, Gabriel Henrique Horta; Botelho, Fernando Mendes; Goneli, André Luis Duarte; Carvalho, Fábia MartinsA secagem de produtos agrícolas é largamente utilizada no mundo para o controle e a manutenção da qualidade dos produtos agrícolas. O objetivo do presente trabalho foi modelar o processo de secagem e obter os parâmetros termodinâmicos de frutos de café (Coffea Arabica L.), cultivar Catuaí Amarelo, para três diferentes condições de temperatura e umidade relativa (35 ºC e 32,1%; 45 ºC e 15,7%; e 55 ºC e 10,2%). Foram utilizados frutos de café colhidos manualmente com teor inicial de água de 1,25 (b.s.) e submetidos à secagem até atingirem o teor médio de 0,13 (b.s). Seis modelos matemáticos usualmente utilizados para a representação do processo de secagem de produtos agrícolas foram ajustados aos dados experimentais. A segunda lei de Fick foi utilizada para obter os coeficientes de difusão dos frutos de café por meio da cinética da secagem. A energia de ativação para a secagem dos frutos de café, bem como a entropia, entalpia e energia livre de Gibbs, foram obtidas. O modelo de Midili modificado foi o que melhor representou o fenômeno de secagem de frutos de café. Os valores do coeficiente de difusão obtidos foram 2,99 x 10-11, 2,39 x 10-11 e 5,98 x 10-11 m2 s-1 para as temperaturas de 35, 45 e 55 ºC, respectivamente. A entalpia diminuiu com o aumento da temperatura do ar de secagem, bem como a entropia. A energia livre de Gibbs aumentou com o aumento da temperatura.Item Modeling of the shrinkage kinetics of coffee berries during drying(Acta Scientiarum. Agronomy, 2011-07) Oliveira, Gabriel Henrique Horta; Corrêa, Paulo Cesar; Botelho, Fernando Mendes; Goneli, André Luis Duarte; Afonso Júnior, Paulo Cesar; Campos, Sílvia CarvalhoThe effects of drying conditions on the shrinkage of Coffea arabica L., cultivar Catuaí Vermelho, were studied. An exponential model derived from the kinetic model was used to describe the shrinkage kinetics. In addition, an equation was proposed to describe the relationship between the superficial areas and weights of the coffee berries. Coffee berries were dried at temperatures (T) of 35, 45, 55 and 65ºC and at relative humidities (φ) of 25, 35, 45 and 55%, forming 16 different sets of conditions, with an initial moisture content for all conditions of 2.27 dry basis (d.b.), dried until 0.11 d.b. Changes in the product dimensions were measured continuously during drying. Surface area-to-volume ratio values increased with moisture content decrease. The model was suitable for representing the shrinkage kinetics, as well the empirical equation for predicting surface area. Temperature had a greater influence over the constant rate of change of the characteristic dimension (k values) than φ. Activation energies were also determined to have magnitudes of 39.31, 37.32, 36.28 and 36.22 kJ mol-1 for relative humidities of 25, 35, 45 and 55%, respectively.Item Modeling the hydration process of bean grains coated with carnauba wax(Semina: Ciências Agrárias, 2017-04-20) Paixão, Aline Almeida da; Corrêa, Paulo Cesar; Baptestini, Fernanda Machado; Donzeles, Sérgio Maurício Lopes; Diniz, Mayra Darliane Martins Silva; Freitas, Rafael Leite deEdible waxes are widely used to maintain foodstuff until they are consumed. However, some products may be subjected to industrial procedures, such as hydration, prior to their consumption. Hydration of a material is a complex process, which aims to reconstitute the original characteristics of a product when in contact with a liquid phase. An important agricultural product that requires this procedure is beans. Thus, the purpose of this work is to study the hydration process of beans (cultivar BRSMG Majestoso) in different temperatures and concentrations of carnauba wax, which is applied on the product surface. Beans with initial moisture content of 0.2015, 0.1972 and 0.1745 (d.b.) corresponding to treatments 0 (witness), 1 (wax diluted in water in the ratio 1:1), and 2 (carnauba wax, without dilution) were used. Later, these samples were imbibed in distilled water at temperatures of 20, 30 and 40 oC, for 15 h. The temperature and the carnauba wax influenced the water absorption rate. The Peleg model described satisfactory experimental data and the Mitscherlich model presented biased residual distribution. The constants C 1 and C 2 of the Peleg model exhibited opposite behaviors with increasing temperatures in the hydration process.Item Moisture desorption isotherms of cucumber seeds: modeling and thermodynamic properties(Journal of Seed Science, 2015-07) Corrêa, Paulo Cesar; Reis, Maycon Fagundes Teixeira; Oliveira, Gabriel Henrique Horta de; Oliveira, Ana Paula Lelis Rodrigues de; Botelho, Fernando MendesHygroscopic equilibrium curves or sorption isotherms are important in order to define dehydration limits of the product, estimate moisture content alterations under environment conditions and to acquire moisture content values for safe storage. This work aimed to determine desorption isotherms of cucumber seeds stored at different temperature (10, 20, 30, 40 and 50 ºC) and relative humidity (0.11 to 0.96) and the thermodynamic properties of this process. Mathematical models were fitted to experimental data in order to represent the agricultural products hygroscopicity. Net isosteric heat of desorption was performed based on the Clausius-Clapeyron thermodynamic relation and Gibbs free energy through the Van't Hoff equation. Based on statistical parameters, Modified Henderson model was the one that best represented hygroscopicity of cucumber seeds. Equilibrium moisture content of cucumber seeds decreased with temperature increment at a constant value of relative humidity. Differential enthalpy values, representing the energy required to remove moisture from the cucumber seeds, ranged from 2923 to 2469 kJ. kg-1. Values of differential entropy and Gibbs free energy decreased with moisture content increase. Enthalpy-entropy compensation theory is valid for the sorption of cucumber seeds, in which the water sorption mechanism in cucumber seeds can be considered to be enthalpy controlled.