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EFFECT OF DRYING METHODS ON THE THERMODYNAMIC PROPERTIES OF BLACKBERRY PULP POWDER

GOMEZ, Gloria I. Giraldo; ORREGO-ALZATE, Carlos E.; GRAJALES, Lina M.; TELIS, Vania R. N.; GABAS, Ana L.; TELIS-ROMERO, Javier
Fonte: UNIV NAC COLOMBIA, FAC NAC MINAS Publicador: UNIV NAC COLOMBIA, FAC NAC MINAS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.08%
Three different types of maltodextrin encapsulated dehydrated blackberry fruit powders were obtained using vibrofluidized bed drying (VF), spray drying (SD), vacuum drying (VD), and freeze drying (FD). Moisture equilibrium data of blackberry pulp powders with 18% maltodextrin were determined at 20, 30, 40, and 50 degrees C using the static gravimetric method for the water activity range of 0.06-0.90. Experimental equilibrium moisture content data versus water activity were fit to the Guggenheim-Anderson-de Boer (GAB) model. Agreement was found between experimental and calculated values. The isosteric heat of sorption of water was determined using the Clausius-Clapeyron equation from the equilibrium data; isosteric heats of sorption were found to increase with increasing temperature and could be adjusted by an exponential relationship. For freeze dried, vibrofluidized, and vacuum dried pulp powder samples, the isosteric heats of sorption were lower (more negative) than those calculated for spray dried samples. The enthalpy-entropy compensation theory was applied to sorption isotherms and plots of Delta H versus Delta S provided the isokinetic temperatures, indicating an enthalpy-controlled sorption process.; Colciencias; CNPq[471223/2006-9]

Study of adsorption isotherms of green coconut pulp; Estudo das isotermas de adsorção da polpa de coco verde

LAVOYER, Fábia Carolina Gonçalves; Gabas, Ana Lucia; Oliveira, Wanderley Pereira de; Romero, Javier Telis
Fonte: Sociedade Brasileira de Ciência e Tecnologia de Alimentos; Campinas Publicador: Sociedade Brasileira de Ciência e Tecnologia de Alimentos; Campinas
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.09%
Brazil is considered one of the largest producers and consumers of tropical fruits. Green coconut (Cocos nucifera L.) stands out not only for its production and consumption, but also for the high amount of waste produced by coconut water industry and in natura consumption. Therefore, there is a need for utilization of this by-product. This study aims to study the adsorption isotherms of green coconut pulp and determine its isosteric heat of sorption. The adsorption isotherms at temperatures of 30, 40, 50, 60, and 70 °C were analyzed, and they exhibit type III behavior, typical of sugar rich foods. The experimental results of equilibrium moisture content were correlated by models present in the literature. The Guggenheim, Anderson and De Boer (GAB) model proved particularly good overall agreement with the experimental data. The heat of sorption determined from the adsorption isotherms increased with the decrease in moisture content. The heat of sorption is considered as indicative of intermolecular attractive forces between the sorption sites and water vapor, which is an important factor to predict the shelf life of dried products.; O Brasil é considerado um dos maiores produtores e consumidores de frutas tropicais. O coco verde (Cocos nucifera L.) se destaca tanto em termos de produção e consumo quanto em quantidade de resíduos gerada por indústrias de água de coco e pelo consumo in natura. Portanto...

Estudo da sorção do antibiótico oxitetraciclina a solos e ácidos húmicos e avaliação dos mecanismos de interação envolvidos; Study of sorption of antibiotic oxytetracycline to the soils and humic acids and evaluation of interaction mechanisms involved

Vaz Júnior, Silvio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/04/2010 PT
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Na atualidade estudos direcionados para a avaliação do risco químico e do impacto ambiental produzidos por compostos químicos de uso intensivo, como agrotóxicos, petroquímicos e fármacos, vêm ganhando importância por elucidarem as implicações ao meio ambiente e à saúde pública decorrentes deste uso pela sociedade moderna de forma a estabelecer parâmetros restritivos para suas aplicações, evitando-se danos posteriores. Este Estudo compreendeu as observações de sorção e de interação do antibiótico de uso animal e agrícola oxitetraciclina (OTC) com solos brasileiros e ácidos húmicos (AH) extraídos de solos, tendo-se como objetivos gerais comprovar a sorção aos solos e aos AH e verificar a influência da matéria orgânica (MO) e do pH sobre a sorção, definindo quais os mecanismos moleculares de interação envolvidos, cabendo destacar que as tetraciclinas são uma das principais classes de antibióticos utilizadas na pecuária brasileira, tanto para tratamento de enfermidades quanto como Antibióticos Promotores de Crescimento (APC), além de serem freqüentemente aplicados na agricultura para controle de fungos e bactérias. Utilizou-se a Cromatografia Líquida de Alta Eficiência (CLAE) para a coleta de dados quantitativos que permitiram a construção de isotermas de sorção solo-OTC em pH 4...

Influence of cooking in sorption isotherms of pinhão (Araucaria angustifolia seeds)

Olivera, Florencia Cladera; Noreña, Caciano Pelayo Zapata; Pettermann, Ana Carolina; Marczak, Ligia Damasceno Ferreira
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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56.81%
The seeds of Araucaria angustifolia, commonly known as pinhão, are widely consumed in both Southern and Southeastern Brazil due to their high nutritious value. Moisture desorption isotherms of cooked pinhão were determined at 15, 25, 30 and 40 oC and modeled using well know isotherm models. Results show that Chirife model most appropriately represents the experimental data as reported previously for raw pinhão. The differential enthalpy was calculated and decreased as moisture content increased, becoming almost constant at 0.3 kg water kg-1 dry solids. Values, for each moisture content, were smaller than those reported for raw pinhão. The enthalpy-entropy compensation theory was applied to desorption isotherms providing the isokinetic temperature (401 ± 17 K). It was found that the desorption process investigated was enthalpy controlled as previously reported for raw pinhão.

INFLUENCE of ENCAPSULATING MATERIALS on WATER SORPTION ISOTHERMS of VACUUM-DRIED PERSIMMON PULP POWDER

Damy Benedetti, Patricia de Carvalho; Marques Pedro, Maria Angelica; Telis-Romero, Javier; Nicoletti Telis, Vania Regina
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 423-431
ENG
Relevância na Pesquisa
47.08%
Water sorption isotherms for vacuum-dried persimmon pulp (PP) powder were determined in the temperature range of 20-50C, and the effects of maltodextrin (MD) or gum arabic (GA) addition on the water sorption behavior of the dried powders were analyzed. Several models were evaluated to fit the experimental data and the Guggenheim-Anderson-de Boer model was selected as the most adequate to describe the observed behavior. Addition of encapsulants affected the isotherms: at the same water activity, PP powder with added GA (PP + GA) or MD (PP + MD) presented lower equilibrium water content than pure PP and were less affected by temperature variations. Samples of PP + MD presented lower equilibrium moisture content than those of PP + GA. The isosteric heats of sorption of pulp powders with encapsulants were higher (less negative) than those of PP, suggesting that there are more active polar sites in PP than in pulp powder containing encapsulants.PRACTICAL APPLICATIONSThe choice of persimmon to carry out this work was due to the large persimmon production available in Brazil; moreover, persimmon pulp is rich in vitamin C, vitamin A and iron, as well as in phenolic compounds. Drying of fruit pulps with high sugar content presents technical difficulties because the hygroscopicity and thermoplasticity of the resulting powders when exposed to high temperature and relative humidity. For this reason...

Thermodynamic properties applied to the sorption isotherms of kiwifruit

Kohayakawa, M. N.; Yamashita, F.; Telis-Romero, J.; Gabas, A. L.; Waliszewski, K. N.
Fonte: Isnt Tecnologico Veracruz Publicador: Isnt Tecnologico Veracruz
Tipo: Conferência ou Objeto de Conferência Formato: 453-462
ENG
Relevância na Pesquisa
57.13%
The net isosteric heat and entropy of water sorption were calculated for kiwifruit, based on sorption isotherms obtained by the static gravimetric method at different temperatures (20 to 70 degreesC). The Guggenheim-Anderson-deBoer equation was fitted to the experimental data, using direct non-linear regression analysis; the agreement between experimental and calculated values was satisfactory. The net isosteric heat of sorption was estimated from equilibrium sorption data, using the Clausius-Clapeyron equation. Isosteric heats of sorption were found to increase with increasing temperature and could be well adjusted by an exponential relationship. The enthalpy-entropy compensation theory was applied to sorption isotherms and plots of DeltaH versus DeltaS provided the isokinetic temperature, T-B = 450.9 +/- 7.7 K, indicating an enthalpy-controlled desorption process over the whole range of moisture content considered.

Water sorption enthalpy-entropy compensation based on isotherms of plum skin and pulp

Gabas, A. L.; Menegalli, F. C.; Telis-Romero, J.
Fonte: Inst Food Technologists Publicador: Inst Food Technologists
Tipo: Artigo de Revista Científica Formato: 680-684
ENG
Relevância na Pesquisa
47.13%
The net isosteric heat and entropy of water sorption were calculated for plum, based on sorption isotherms obtained by the static gravimetric method at different temperatures (20 to 70 degrees C). The Guggenheim-Anderson-deBoer model was applied to the experimental data giving a good agreement between experimental and calculated values. The net isosteric heat of water sorption, estimated by applying Claussius-Clapeyron equation to sorption isotherms, was found to be different for plum skin and pulp, mainly at low moisture contents, and could be well adjusted by an empirical exponential relationship. Plots of enthalpy in contrast to entropy provided the isokinetic temperatures for skin and pulp, indicating an enthalpy-controlled sorption process. Thermodynamic data on water sorption for plums are not found in literature, as opposed to prunes for which the data are abundant.

Thermodynamic models for water sorption by grape skin and pulp

Gabas, A. L.; Telis-Romero, J.; Menegalli, F. C.
Fonte: Marcel Dekker Inc Publicador: Marcel Dekker Inc
Tipo: Artigo de Revista Científica Formato: 961-974
ENG
Relevância na Pesquisa
57.01%
The enthalpy-entropy compensation theory was applied to water sorption for grapes of Italy variety. The moisture sorption isotherms were analyzed using the static gravimetric method at 35, 40, 50, 60, 70 and 75 degrees C. For isotherms construction, the skin and pulp of the grape were used separately and it was possible to observe significant differences. The GAB equation was fitted to the experimental data, using direct nonlinear regression analysis; the agreement between experimental and calculated values was satisfactory. The net isosteric heat or enthalpy of water sorption, determined from the equilibrium sorption data, showed a different behavior when compared with other works, as it was obtained for skin and pulp separately. Plots of Delta h vs Delta S for skin and pulp provided the isokinetic temperatures T-Bs = 423.2 +/- 27.6 K and T-Bp = 424.5 +/- 25.3 K, respectively, indicating an enthalpy-controlled desorption process over the whole range of moisture content considered.

Water sorption and plasticization of an amorphous galacto-oligosaccharide mixture

Torres, D.; Bastos, Margarida; Gonçalves, M. P.; Teixeira, J. A.; Rodrigues, L. R.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2011 ENG
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56.81%
Food-grade galacto-oligosaccharides (GOS) are commercially available as transparent syrups or dried powders. Food powders can be found in an amorphous metastable state which is very sensitive to changes in temperature and moisture content. In this work the impact of water content on thermal behavior and relative humidity on water sorption behavior of amorphous GOS powders were studied. Results from differential scanning calorimetry (DSC) and sorption isotherms suggest that GOS mixture studied, with high content of oligosaccharides, has low ability to crystallize. A dramatic decrease in the stability of GOS powders occurred above critical water content (12–14 g/100 g) and corresponding critical water activity (0.55–0.62). Above these conditions GOS powder lost its amorphous character, collapsed and shrank, as the powder became a transparent “solution-like” material. The knowledge about the physicochemical changes, acquired during the present study, should be used to a proper control of processing and storage conditions to achieve and maintain optimum powder quality with desired properties.; Agência da Inovação (ADI) - Project BIOLIFE – PRIME 03/347; Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BDE/15510/2004

Role of Sorption Isotherms in the Analysis of Coupled Heat and Mass Fluxes in Porous Media

Reis, A. Heitor; Rosa, Rui
Fonte: Begell House Publicador: Begell House
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.85%
The aim of this work is to show the importance of the sorption isotherms in the study of the heat and mass fluxes in unsaturated porous media. General forms of the heat and mass fluxes are presented in terms of experimentally accessible quantities. The role of the isotherm slope in the coupling of heat and mass fluxes and its influence on the effective permeability are shown. Separate relations for vapor and liquid fluxes through the porous medium are presented as functions of the temperature and the isotherm slopes. Nonstationary isothermal mass flux is also analyzed, a relaxation time for this process is identifled, and its relation to the isotherm slope is also discussed.

Sorption isotherms of Portuguese varieties of pears.

Barroca, Maria João
Fonte: Instituto Politécnico de Viseu Publicador: Instituto Politécnico de Viseu
Tipo: Conferência ou Objeto de Conferência
Publicado em //2005 ENG
Relevância na Pesquisa
56.86%
In this study the desorption isotherms of fresh pears were investigated at 30 ºC for fruits of the varieties Amêndoa, Amorim, Carapinheira Branca and S. Bartolomeu, all original from Portugal. This value of temperature was established to represent the summer average daily temperatures in Portugal, where the solar dried of pears is carried out. From the results obtained it was possible to verify that the behaviour of the equilibrium moisture content against the corresponding water activity is very similar for the four varieties of pears, and is of type III according to the Brunauer et al. (1940) classification of isotherms, very characteristic of products rich in carbohydrates (Vásquez-Uña, 2001; Rizvi, 1986). The experimental data were fitted to the Guggenheim-Anderson-deBoer (GAB), Halsey, Hendersen and Oswin models found in literature (Viswanathan, 2003). The performance of these models was evaluated by comparing the coefficient of correlation (R), the residuals of moisture content and the prediction capabilities. From the results obtained it was possible to conclude that the Oswin model is less appropriate for describing the process at study, and that the Chen and Halsey models are also not very adequate. The Henderson and GAB models...

Moisture sorption isotherms and isosteric heat determination in Chilean papaya (Vasconcellea pubescens)

Vega-Gálvez,Antonio; Palacios,Marlene; Lemus-Mondaca,Roberto; Passaro,Catarina
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
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The moisture sorption isotherms of Chilean papaya were determined at 5, 20, and 45 ºC, over a relative humidity range of 10-95%. The GAB, BET, Oswin, Halsey, Henderson, Smith, Caurie and Iglesias-Chirife models were applied to the sorption experimental data. The goodness of fit of the mathematical models was statistically evaluated by means of the determination coefficient, mean relative percentage deviation, sum square error, root-mean-square error, and chi-square values. The GAB, Oswin and Halsey models were found to be the most suitable for the description of the sorption data. The sorption heats calculated using the Clausius-Clapeyron equation were 57.35 and 59.98 kJ·mol-1, for adsorption and desorption isotherms, respectively.

Sorption and desorption of Suflafenacil in two soils in the state of São Paulo with different physical and chemical attributes

Matallo,M.B.; Franco,D.A.S.; Almeida,S.D.B.; Cerdeira,A.L.
Fonte: Sociedade Brasileira da Ciência das Plantas Daninhas Publicador: Sociedade Brasileira da Ciência das Plantas Daninhas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
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A study was conducted to evaluate the sorption and desorption of 14C herbicide saflufenacil (pyrimidinedione) in two soils in the State of São Paulo, classified as Red Yellow Latosol with clayey texture (LVA-1) and medium texture (LVA-2), using the batch method through isotherms. The soils were air dried and sieved a 2 mm mesh. The radioactivity was determined by liquid scintillation spectrometry in acclimatized room (25 ± 2 °C). Sorption isotherms were conducted for 5 concentrations of saflufenacil (5.0; 2.5; 1.0; 0.5 and 0.05 μg mL-1) and the results were adjusted to the Freundlich equation, thus obtaining the parameters of sorption followed by two extractions with 0.01 M CaCl2 to determine desorption parameters similarly to sorption. The results showed that saflufenacil sorption was low for both soils studied, being greater for the LVA with higher organic matter content. The desorption coefficients were greater than their sorption coefficients, suggesting the occurrence of hysteresis. The sorption and desorption isotherms (classified as type C isotherms), hysteresis and the t-test between the angular coefficient of the respective isotherms showed that both the sorption and desorption occur with equal intensity.

Study of adsorption isotherms of green coconut pulp

Lavoyer,Fábia Carolina Gonçalves; Gabas,Ana Lúcia; Oliveira,Wanderley Pereira; Telis-Romero,Javier
Fonte: Sociedade Brasileira de Ciência e Tecnologia de Alimentos Publicador: Sociedade Brasileira de Ciência e Tecnologia de Alimentos
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 EN
Relevância na Pesquisa
47.09%
Brazil is considered one of the largest producers and consumers of tropical fruits. Green coconut (Cocos nucifera L.) stands out not only for its production and consumption, but also for the high amount of waste produced by coconut water industry and in natura consumption. Therefore, there is a need for utilization of this by-product. This study aims to study the adsorption isotherms of green coconut pulp and determine its isosteric heat of sorption. The adsorption isotherms at temperatures of 30, 40, 50, 60, and 70 °C were analyzed, and they exhibit type III behavior, typical of sugar rich foods. The experimental results of equilibrium moisture content were correlated by models present in the literature. The Guggenheim, Anderson and De Boer (GAB) model proved particularly good overall agreement with the experimental data. The heat of sorption determined from the adsorption isotherms increased with the decrease in moisture content. The heat of sorption is considered as indicative of intermolecular attractive forces between the sorption sites and water vapor, which is an important factor to predict the shelf life of dried products.

Electroanalytical procedure for the determination of methylparathion in soil suspensions and its application for sorption studies with Brazilian soils

Castanho,Giuliane M.; Vaz,Carlos M. P.; Machado,Sérgio A. S.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2003 EN
Relevância na Pesquisa
56.86%
The differential pulse polarography technique was used to establish an electroanalytical procedure for the determination of the organophosphorous insecticide methyl parathion (O,O-dimethyl O-(4-nitrophenyl) phosphorothioate) in soil samples. Three reduction peaks were observed in mercury electrodes as a function of the solution pH. The more cathodic peak (Ep= -0.55V), only observed for pH values higher than 5.0, was chosen for the analytical determinations. The limit of detection was 1.93x10-8 mol L-1 for pure water and about 8x10-8 mol L-1 for soil suspensions with a scan rate of 2 mV s-1 and a pH of 6.75. The electroanalytical procedure developed was applied for the determination of sorption isotherms of methylparathion on 3 soils from São Paulo State, Brazil, at different pH and diverse amounts of clay and organic matter. The experimental data were fitted using the Freundlich isotherm model and the Freundlich coefficients (K F) obtained for each soil varied from 7 to 29 L kg-1, representing a low to medium sorption capacity, according to the IBAMA (Brazilian Environmental Protection Agency) standards. The amounts of organic matter and clay were the most important soil parameters controling the sorption of methylparathion by these soils.

Sorption and desorption of Suflafenacil in two soils in the state of São Paulo with different physical and chemical attributes.

MATALLO, M. B.; FRANCO, D. A. S.; ALMEIDA, S. D. B.; CERDEIRA, A. L.
Fonte: Planta Daninha, Viçosa, v. 32, n. 2, p. 393-399, 2014. Publicador: Planta Daninha, Viçosa, v. 32, n. 2, p. 393-399, 2014.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
57.24%
Resumo: Foi conduzido um estudo para avaliar a sorção e dessorção do herbicida saflufenacil em dois solos do Estado de São Paulo: um Latossolo Vermelho-Amarelo com textura argilosa (LVA-1) e outro com textura média (LVA-2), classificados como argiloso e franco-argiloarenoso, respectivamente, através de isotermas, utilizando o método em batelada. Os solos foram secos ao ar e peneirados em malha de 2 mm. A molécula radiomarcada com 14C foi o saflufenacil, herbicida do grupo das pirimidinadionas. A radioatividade foi determinada por espectrometria de cintilação líquida. Os ensaios foram realizados em sala climatizada (25 ± 2 ºC). Para determinação de sorção e isotermas de sorção, foram empregadas cinco concentrações do saflufenacil (5,0; 2,5; 1,0; 0,5; e 0,05 ?g mL-1), sendo os resultados ajustados à equação de Freundlich, obtendo-se assim os parâmetros de sorção. Na sequência, foram realizadas duas extrações com 0,01 M de CaCl2, determinando-se os parâmetros de dessorção de forma similar à sorção. Os resultados mostraram que a sorção do saflufenacil foi baixa para ambos os solos, sendo maior para o LVA com maior teor de matéria orgânica. Os coeficientes de dessorção foram maiores do que os respectivos coeficientes de sorção...

Competitive sorption of cadmium and lead in acid soils of Central Spain

Serrano, S.; Garrido, Fernando; Campbell, C. G.; García González, María Teresa
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 22195 bytes; application/pdf
ENG
Relevância na Pesquisa
57.16%
14 pages, and tables stadistics.; The bioavailability and ultimate fate of heavy metals in the environment are controlled by chemical sorption. To assess competitive sorption of Pb and Cd, batch equilibrium experiments (generating sorption isotherms) and kinetics sorption studies were performed using single and binary metal solutions in surface samples of four soils from central Spain. For comparisons between soils, as well as, single and binary metal solutions, soil chemical processes were characterized using the Langmuir equation, ionic strength, and an empirical power function for kinetic sorption. In addition, soil pH and clay mineralogy were used to explain observed sorption processes. Sorption isotherms were well described by the Langmuir equation and the sorption kinetics were well described by an empirical power function within the reaction times in this study. Soils with higher pH and clay content (characterized by having smectite) had the greatest sorption capacity as estimated by the maximum sorption parameter (Q) of the Langmuir equation. All soils exhibited greater sorption capacity for Pb than Cd and the presence of both metals reduced the tendency for either to be sorbed although Cd sorption was affected to a greater extent than that of Pb. The Langmuir binding strength parameter (k) was always greater for Pb than for Cd. However...

Equipamento experimental para determinação de isotermas de adsorção pelo método dinâmico; Experimental apparatus for the determination of sorption isotherms by the dynamic method

Padro Filho, L.G.; Sabbagh, M.
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/12/1993 POR
Relevância na Pesquisa
56.81%
Foi realizada a avaliação do desempenho de equipamento experimental para a determinação de curvas de umidade de equilíbrio - isoterma de adsorção - de farinhas pelo método dinâmico. Para o ajuste dos valores definidos (0,51; 0,57; 0,67; 0,75; 0,79 e 0,81) de atividade de água - Aa - na corrente de ar, foram usadas soluções saturadas de sais. A comparação da eficiência do equipamento, com e sem recirculação de ar, foi feita determinando-se a isoterma de adsorção de farinha de soja a 35°C. A versão com recirculação de ar permite a obtenção de dados de equilíbrio em elevados níveis de Aa, nos quais há perda das amostras por crescimento microbiano quando se emprega a versão sem recirculação. Os tempos necessários para a obtenção do equilíbrio da farinha com as umidades relativas das correntes de ar são cerca de 50% menores na versão com recirculação de ar.; The evaluation of the performance of an experimental apparatus for the determination of flour sorption isotherms was carried out. To adjust the water activity - Aa - values (0.51; 0.57; 0.67; 0.75; 0.79 and 0.81) of the air stream, saturated salt solutions were used. The comparison of the apparatus with and without air recycling, was done by determining the sorption isotherm of soybean flour at 35°C. The air recycling model enables to obtain reliable data in a high Aa range...

SORPTION ISOTHERMS FOR FOOD PRODUCTS: STUDY OF MODELS AGREEMENT

NASCIMENTO, FABIANO RIBEIRO; Universidade Federal de Lavras - MG; CÔRREA, JEFFERSON LUIZ GOMES; Universidade Federal de Lavras - MG; BORGES, SORAIA VILELA; Universidade Federal de Lavras - MG; TOSATO, POLIANA GASPAR; Universidade Federal de Lavras - MG
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 26/08/2011 POR
Relevância na Pesquisa
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The knowledge of sorption isotherms is important for establishing conditions of storage and of processes like drying. There are several models for fitting sorption isotherms. This work presents a study about the agreement of 40 mathematical models of sorption isotherms to experimental data of 53 food products. The quadratic residual sum and the standard error were the criteria of evaluation. For the major part of the products, the best agreement was obtained with equation of Jaafar and Michalowski, if temperature or saturation pressure were not considered as a variable. For cases where temperature or saturation pressure were considered, the equation of Strohman and Yoerger was the one with the best agreement for most of the products. Ross equation, based on thermodynamics aspects, was also tested for some products, but the agreement was just satisfactory.

Comparison between the isotherms of two commercial types of textured soy protein

Cassini,A.S.; Marczak,L.D.F.; Noreña,C.P.Z.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
Relevância na Pesquisa
56.85%
Textured soy proteins (TSP) are functional ingredients used in food applications. This study aims to compare the sorption isotherms of two commercial types of TSP at 10, 20, 30 and 40 °C; the best fit to the experimental data was selected from eight classical models. The curves obtained for TSP type I showed that the equilibrium moisture content decreases as temperature increases for water activities up to 90%. At higher water activities, the moisture content showed an inverse behavior. This inversion did not occur for TSP type II due to the absence of sugars in this type of TSP. The Chirife, GAB and Peleg equations presented the best fit for the curves.