Sorption isotherms of cocoa and cupuassu products

Medeiros, Magda Leite; Ayrosa, Ana Maria Irene Bartolomeu; Pitombo, Ronaldo Nogueira de Moraes; Lannes, Suzana Caetano da Silva

doi:10.1016/j.jfoodeng.2005.02.002

Cited by 48 publications

(38 citation statements)

References 10 publications

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“…The modified GAB model gave a better fit than the original model for the experimental data obtained from the moisture adsorption isotherms in the range from 0.10 to 0.90 a w (Table 3). As the parameters of the GAB equation are based on the physical phenomena involved in water adsorption by hydrophilic materials, it is considered the most suitable model to describe experimental data (Bratasz et al, 2012;Figura & Teixeira, 2007;Furmaniak et al, 2007;Lavoyer et al, 2013;Medeiros et al, 2006;Souza et al, 2015;Timmermann et al, 2001;Zhang & Han, 2008).…”

Section: Modeling Of Experimental Datamentioning

confidence: 99%

Modelling the effect of temperature on the water sorption isotherms of chitosan films

2016

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The interaction of the water molecules from the environment with foods and other materials can be evaluated using sorption isotherms. Films and biodegradable films are susceptible to changes in their functional characteristics due to adsorbed water. The amount of moisture that biodegradable films can adsorb depends on the temperature, relative humidity of the storage area and chemical composition. Several mathematical models can be used to describe the behavior of sorption isotherms in biodegradable films and some of them have been modified to include the temperature parameter into the equation. In this research, the original and modified BET, GAB, Halsey, Henderson and Dswin models were assessed to determine their suitability describing the behavior of moisture adsorption isotherms of chitosan films at 15, 20, 25 and 30 °C. The modified models of GAB, Dswin and Halsey gave the best fit to the experimental sorption data of the chitosan films, with R 2 values higher than 0.97 demonstrating that those models describe better the sorption isotherms at the temperatures studied.Keywords: chitosan film; moisture adsorption isotherm; GAB model. Practical Application:The knowledge of the relationship between the equilibrium moisture content, equilibrium relative humidity and temperature is very important in order to describe the effect of water activity on storage of foods. Several mathematical models were used to describe the water sorption behavior of chitosan edible films involving water activity, moisture content and temperature.

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Section: Modeling Of Experimental Datamentioning

confidence: 99%

Modelling the effect of temperature on the water sorption isotherms of chitosan films

2016

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“…More recently, GAB model gave the best fit of the sorption isotherms of cocoa and cupuassu products at 15 °C, 30 °C and 35 °C (Medeiros, 2006).…”

Section: Introductionmentioning

confidence: 99%

Desorption Isotherms and Isosteric Heats of Fermented Cocoa Beans (Theobroma cocoa)

Akmel¹,

Kakou²,

Kone³

et al. 2015

JFR

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Water desorption isotherms of fermented cocoa beans from Ivory Coast were determined using the gravimetric static method of saturated salts solutions at 30 °C, 40 °C and 60 °C, and isosteric heats of desorption were calculated from Clausius-Clapeyron equation. The experimental data were fitted to several isotherm equations. The best fittings were obtained for the BET equation for aw<0.50 (with an average mean relative deviation (MRD) value of 1.56%) and for the Harkins-Jura equation for aw≥0.50 (with an average value MRD equation of 4.17%). The isotherms obtained at 30 °C and 40 °C are practically coincident and overlapped for aw below 0.40. Fermented cocoa beans presented a monolayer moisture content of 0.083 dry basis (d.b.) at 30 °C and this value decreases with increasing temperature. The net isostheric heats of desorption for fermented cocoa beans for the temperature range studied (30-60 °C) were estimated as a function of moisture content. The maximum net isosteric heat of desorption for fermented cocoa beans was estimated at around 13.51 kJ/mol corresponding to a moisture content value of 2.85%. The energy requirement for maintaining the moisture content low of 8.7% (d.b.) or 8% wet basis (w.b.) for safe storage of this product or for reducing the moisture content during drying was estimated at around 9.58 kJ/mol.

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“…O cálculo do valor monomolecular através da equação de BET torna-se progressivamente impreciso à medida que o valor de C se aproxima da unidade. [10] [5,6], trabalhando com colágeno de tendão bovino, por cristalografia, encontraram valores semelhantes aos nossos para o teor de umidade na camada monomolecular.…”

Section: Ajuste Das Isu Aos Modelos Matemáticos De Bet E Gabunclassified

“…Os modelos são considerados satisfatórios quando %E for menor ou igual a 10%. [2,10] O modelo BET ajustou perfeitamente as curvas de adsorção e dessorção de umidade em todas as temperaturas estudadas. O modelo GAB apresentou valores de %E superiores a 10% nas curvas de dessorção a 25 e 35°C.…”

Section: Ajuste Das Isu Aos Modelos Matemáticos De Bet E Gabunclassified

“…[7] Neste trabalho estudou-se o comportamento higroscópico de PB, tratado com glutaraldeído, com o objetivo de estabelecer a termodinâmica de sorção de água e verificar a aplicabilidade de modelos matemáticos (Tabela 1): 1) de Brunauer-Emmett-Teller (BET), modelo cinético baseado na formação de camada monomolecular pelo processo de adsorção de vapor de água pela superfície do sólido seco a baixas pressões de vapor; 2) de Guggenheim-Anderson-de Boer (GAB), é considerado mais eficiente por aplicar-se em todo o intervalo da ISU. [4,10]; e 3) a equação de Clausius-Clapeyron aplicado no cálculo do calor de adsorção do material estudado. [3] Tabela 1: Modelos matemáticos aplicados as ISU de PB liofilizado.…”

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Estudo do comportamento higroscópico do pericárdio bovino liofilizado

et al. 2007

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RESUMOO comportamento higroscópico de produtos desidratados pode ser visualizado a partir da construção de curvas denominadas Isotermas de Sorção de Umidade (ISU). Esse tipo de curva relaciona a quantidade máxima de água absorvida por uma substância, com a pressão de vapor de equilíbrio ou a atividade de água, numa dada temperatura mantida constante. Com o objetivo de estudar posteriormente a reconstituição, material de embalagem e utilização de implantes feitos a partir de pericárdio bovino liofilizado, foram traçadas curvas de adsorção e dessorção de umidade em um analisador de sorção de vapor de água, Hydrosorb TM 1000, nas temperaturas de 15, 25 e 35°C. Os resultados obtidos mostraram ISU tendendo ao tipo II, segundo a classificação de BET, reação típica de superfícies hidrofílicas com formação de monocamada e multicamadas. O fenômeno da histerese foi observado durante todo o intervalo da ISU. Os modelos matemáticos de Brunauer-Emmett-Teller (BET) e Guggenheim-Anderson-de Boer (GAB) ajustaram bem os dados experimentais permitindo o cálculo do valor monomolecular, importante para a estimativa do nível crítico de umidade residual que confere maior estabilidade de armazenamento ao produto.Palavras chaves: Liofilização, pericárdio bovino, comportamento higroscópico, isotermas de sorção de umidade. Hygroscopic behavior of lyophilized bovine pericardium ABSTRACTHygroscopic behavior of lyophilized products can be visualized starting from the construction of Moisture Sorption Isotherms (MSI). Such curves show the relationship between the maximum amount of absorbed water for a substance, with the equilibrium vapor pressure or water activity, at a given constant temperature. Aimed to study later the reconstitution and use of biological materials of lyophilized bovine pericardium, it was plot adsorption and desorption curves, at temperatures of 15, 25 and 35°C, on Hydrosorb TM 1000 -water vapor sorption analyzer. The results showed MSI type II, according BET classification, typical reaction of hydrophilic surfaces with monolayer and multilayer formation. Histerese phenomenon was observed during the whole MSI interval. The mathematical models of BET and GAB fitted well the experimental data and allowed the water monolayer calculation, estimate the critical level of residual moisture that assures more stability to the product.

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Sorption isotherms of cocoa and cupuassu products

Cited by 48 publications

References 10 publications

Modelling the effect of temperature on the water sorption isotherms of chitosan films

Modelling the effect of temperature on the water sorption isotherms of chitosan films

Desorption Isotherms and Isosteric Heats of Fermented Cocoa Beans (Theobroma cocoa)

Estudo do comportamento higroscópico do pericárdio bovino liofilizado

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