Sorption isotherms, GAB parameters and isosteric heat of sorption

Quirijns, E.J.; Boxtel, A.J.B. van; Loon, W.K.P. van; Straten, G. van

doi:10.1002/jsfa.2140

Cited by 268 publications

(270 citation statements)

References 38 publications

(75 reference statements)

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“…The impact of temperature on the sorption capacity of rice was more obvious in the desorption data compared to the adsorption. The increase in EMC at the lower temperature is probably because the kinetic energy that the water molecules are holding is insufficient to free them from their corresponding sorption sites (Quirijns et al 2005). Moreover, water molecules form hydrogen bounds along with hydrophilic groups of the biopolymer such as starch, proteins.…”

Section: Resultsmentioning

confidence: 99%

Sorption isotherms and isosteric heats of sorption of Malaysian paddy

et al. 2012

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Understanding the water sorption characteristics of cereal is extremely essential for optimizing the drying process and ensuring storage stability. Water relation of rough rice was studied at 20, 30, 40 and 50°C over relative humidity (RH.) between 0.113 and 0.976 using the gravimetric technique. The isotherms displayed the general sigmoid, Type II pattern and exhibited the phenomenon of hysteresis where it was more pronounced at lower temperatures. The sorption characteristics were temperature dependence where the sorption capacity of the paddy increased as the temperature was decreased at fixed (RH). Among the models assessed for their ability to fit the sorption data, Oswin equation was the best followed by the third order polynomial, GAB, Smith, Chung-Pfost, and Henderson models. The monolayer moisture content was higher for desorption than adsorption and tend to decrease with the increase in temperature. Given the temperature dependence of the sorption isotherms the isosteric heats of sorption were calculated using Claussius-Clapeyron equation. The net isosteric heats decreased as the moisture content was increased and heats of desorption were greater than that of adsorption.

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Section: Resultsmentioning

confidence: 99%

Sorption isotherms and isosteric heats of sorption of Malaysian paddy

et al. 2012

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“…The parameters are the moisture content in the monolayer (x m ) and the energy involved in the process of water adsorption (c). x m is the amount of water which is adsorbed strongly at specific binding sites on the surface of the material and can also be set as a measure of the availability of active sites of a material for the adsorption of water molecules (Figura & Teixeira, 2007;Lavoyer et al, 2013;Quirijns et al, 2005). In the chitosan-based films, BET model fitted appropriately the range from 0 to 0.75 a w .…”

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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“…Therefore, the binding energy between the adsorbent surface and water will decrease from the strong binding energy at the monolayer to zero at the outer layers. In the outer layers, far from the adsorbent surface, the water molecules show properties similar to those of liquid water [30].…”

Section: Desorption Isothermsmentioning

confidence: 99%

“…A water sorption isotherm is a fundamental relationship that describes the dependence of water content within a solid-water mixture on the water activity, at a certain pressure and temperature [30]. The Guggenheim, Anderson and de…”

Section: Desorption Isothermsmentioning

confidence: 99%

“…X m is known as the monolayer moisture content and it is interpreted as a measure of the number of active sites available for water sorption in the material. The value of this parameter is expected to decrease as the temperature is increased, due to the destruction of the active sites available for water sorption [30]. The parameters C g and K represent the nature of the water-material interaction.…”

Section: Desorption Isothermsmentioning

confidence: 99%

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A Neural Based Modeling Approach for Drying Kinetics Analysis of Mint Branches and Their Fractions (Leaves and Stems)

Rosanova¹,

Maia²,

Freire³

et al. 2017

ACES

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This work is aimed at investigating regular mint (Mentha × villosa) drying behavior and assessing how the heterogeneous composition of plants affects their drying kinetics. Drying kinetics and sorption isotherms were evaluated for whole branches and their fractions (leaves and stems). Stems and leaves were characterized by measurement of dimensions, apparent density and initial moisture content. The moisture sorption isotherms were obtained under temperatures of 30˚C, 40˚C and 50˚C for branches, stems and leaves and the data were fitted to the GAB model. Mint branches and their fractions were oven dried at temperatures from 40˚C to 70˚C and were obtained kinetic curves for each part. Water sorption patterns were similar for leaves and stems and the GAB model described well the sorption behavior of both materials. At a constant temperature, the drying rates were higher for leaves in comparison to stems and the differences increased as the temperature was raised. Therefore, depending on drying conditions, the moisture distribution in dried branches might be significantly different. Since the leaves constitute the major fraction in branches, the drying rates of branches were closer to those of leaves. The kinetic curves were fitted to a diffusion model based on an analytical solution of Fick's second diffusion law and to an empirical model based on artificial neural network (ANN). The results showed that the model based on the ANN predicted the drying kinetics of the different parts better than the diffusive model. A single network was built to describe the kinetic behavior of branches and fractions in the whole range of temperatures investigated. The diffusive model based on fitting effective diffusivity did not provide good predictions of moisture content, probably because neither the dependence of effective diffusivity on the moisture content nor the heterogenei- 155ty and shrinking of static beds were considered.

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Sorption isotherms, GAB parameters and isosteric heat of sorption

Cited by 268 publications

References 38 publications

Sorption isotherms and isosteric heats of sorption of Malaysian paddy

Sorption isotherms and isosteric heats of sorption of Malaysian paddy

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

A Neural Based Modeling Approach for Drying Kinetics Analysis of Mint Branches and Their Fractions (Leaves and Stems)

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