scholarly journals Isotherms and Isosteric Heat Desorption of Hymenaea stigonocarpa Mart. Seeds

2018 ◽  
Vol 10 (10) ◽  
pp. 504 ◽  
Author(s):  
Weder N. Ferreira Junior ◽  
Osvaldo Resende ◽  
Daniel E. C. de Oliveira ◽  
Lílian M. Costa
Keyword(s):  
Mathematical Model ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Information Criterion ◽  
Isosteric Heat ◽  
Brazilian Cerrado ◽  
Harvest Management ◽  
Statistical Parameters ◽  
Modified Model ◽  
The One

The Brazilian Cerrado is one of the most important ecosystems and due to the extractivism it is necessary to recover the degraded areas. The tree of Hymenaea stigonocarpa Mart. is used in this reforestation system, so the study of post-harvest management of the seed is necessary for the propagation. The objective of this work was to determine the isotherms and the isosteric desorption heat of Hymenaea stigonocarpa Mart. Seeds, and to test the methodology of the Akaike’s information criterion (AIC) and Schwarz’s bayesian information criterion (BIC) for the choice of the best mathematical model. Different mathematical models were fitted to the experimental data and the model that best represents the phenomenon was selected, from the statistical parameters. To obtain the equilibrium moisture content was used static method using desiccants in incubators cameras with control of relative humidity by salt solution. The Oswin Modified model obtained better results according to analyzed parameters, being this model the one selected for prediction of the hygroscopic balance of the Hymenaea stigonocarpa Mart. seeds. It was found that the higher the temperature for the same equilibrium moisture content, the higher the water activity values. The AIC and BIC methodology contributed to the choice of the best mathematical model to predict the hygroscopicity phenomenon. The isosteric heat increased with the decrease in the equilibrium moisture content requiring a greater amount of energy to remove water from the seeds.

Sorption Isotherms and Isosteric Heat of Peanut Pods, Kernels and Hulls

2007 ◽  
Vol 13 (3) ◽  
pp. 231-238 ◽  
Author(s):  
P.C. Corrêa ◽  
A.L.D. Goneli ◽  
C. Jaren ◽  
D.M. Ribeiro ◽  
O. Resende
Keyword(s):  
Experimental Data ◽  
Relative Humidity ◽  
Moisture Content ◽  
Mathematical Models ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Statistical Parameters ◽  
Peanut Hulls ◽  
Pass Through

This study was carried out to evaluate the sorption isotherms of peanut pods, kernels and hulls for several temperature and humidity conditions and to fit different mathematical models to the experimental data, selecting the one best fitting the phenomenon. The dynamic method was applied to obtain the hygroscopic equilibrium moisture content. The environmental conditions were provided by means of an atmospheric conditioning unit, in which removable perforated trays were placed to allow air to pass through peanut mass, each one containing 50 g of the product. The mathematical models frequently used for the representation of hygroscopicity of agricultural products were fit to the experimental data. Based on those results, it was concluded that peanut pods, kernels and hulls presented differentiated hygroscopicity. The equilibrium moisture content for peanut pods, kernels and hulls increased with an increase in the relative humidity at any particular temperature and decreased with increase in temperature at constant relative humidity. At a constant water activity, peanut hulls samples had higher equilibrium moisture content than the pods and kernels samples. Based on statistical parameters, the modified Henderson and Chung-Pfost models were found to adequately describe the sorption characteristics of peanut pods, kernels and hulls. Isosteric heat of desorption were evaluated by applying the Clausius—Clapeyron equation to experimental isotherms and decreased with increasing moisture content. The peanut hulls had higher isosteric heat of sorption than that peanut pods and kernels.

scholarly journals Determination of desorption isotherms, latent heat and isosteric heat of pequi diaspore

2016 ◽  
Vol 20 (5) ◽  
pp. 493-498 ◽  
Author(s):  
Kelly A. de Sousa ◽  
Osvaldo Resende ◽  
Bruno de S. Carvalho
Keyword(s):  
Moisture Content ◽  
Latent Heat ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Static Method ◽  
The One ◽  
Content Range ◽  
Water Sorption Isotherms

ABSTRACT The objective was to determine water sorption isotherms of diaspores of pequi fruits in order to obtain information on the amount of water that this product desorbs at the temperatures of 10, 20, 30 and 40 °C and water activities from 0.20 to 0.89, adjusting different mathematical models to experimental data, and to determine its latent heat and isosteric heat. The equilibrium moisture content was obtained through the indirect static method, using the device Hygropalm Model Aw 1. The Modified Henderson model was the one that best fitted the data and was selected to predict the equilibrium moisture content of pequi diaspore. It was observed that the higher the temperature for the same equilibrium moisture content (% d.b.), the higher the water activity values. As temperature values increased, there was a reduction in the vaporization latent heat of the product. Isosteric heat values of diaspores of pequi fruits in the moisture content range of 4.02 to 16.63 (% d.b.) varied from 2,776.49 to 2,558.39 kJ kg-1.

scholarly journals Isotermas e calor isostérico de dessorção das sementes de tungue

2021 ◽  
Vol 1 (54) ◽  
pp. 163
Author(s):  
Lílian Moreira Costa ◽  
Osvaldo Resende ◽  
Weder Nunes Ferreira Junior ◽  
Daniel Emanuel Cabral de Oliveira ◽  
Igor Olacir Fernandes Silva
Keyword(s):  
Mathematical Model ◽  
Moisture Content ◽  
Information Criterion ◽  
Isosteric Heat ◽  
Static Method ◽  
Biodiesel Production ◽  
Salt Solutions ◽  
Equilibrium Water Content ◽  
Desorption Isotherms ◽  
Content Range

<p><span class="fontstyle0">The tung is a species that has potential for biodiesel production, so for safe storage there is a need to get to know its hygroscopicity. The objective of this work was to determine the desorption isotherms based on the recommendation of a mathematical model, to define the safe moisture content for storage, and to obtain the isosteric heat for the tung seeds. In order to obtain the hygroscopic equilibrium water content, the static method was used, with 20g of seeds surrounded by a permeable tissue, and placed inside the desiccators containing salt solutions, in a BOD chamber with temperatures of 20, 25, At 30 and 35 ºC, water activity ranged from 0.14 to 0.812 decimal.The Akaike information criterion (AIC) and Bayesian Schwarz information criterion (BIC) were used to adjust the mathematical models and to help choose the best one. Among the tested models, ChungPfost was  elected to represent the desorption isotherms of tung seeds. Integral isosteric desorption heat values in the equilibrium moisture content range from 2.08 to 8.35 (% b.s.) ranged from 3754 to 2555 kJ kg</span><span class="fontstyle0">-1</span> <br /><br /></p>

Adsorption Isotherms for Red Onion Slices Using Empirical and Neural Network Models

2011 ◽  
Vol 7 (6) ◽  
Author(s):  
Hamid Reza Gazor ◽  
Afshin Eyvani
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Multilayer Perceptron ◽  
Sorption Isotherms ◽  
Network Models ◽  
Isosteric Heat ◽  
Neural Network Models ◽  
Isosteric Heat Of Adsorption

Moisture sorption isotherms of red onion slices were determined at 30, 40, 50, and 60°C using the standard gravimetric static method over a range of relative humidity from 0.11 to 0.83. The experimental sorption curves were fitted by seven empirical equations: modified Henderson, modified Chung–Pfost, modified Halsey, modified Oswin, modified Smith, modified BET, and GAB. Also three types of Artificial neural network models: linear, multilayer perceptron, and radial basis function were tested and developed to predict the equilibrium moisture content of onion slices and the selected models were trained by using related algorithms. The modified Oswin model was found acceptable for predicting adsorption moisture isotherms and fitting to the experimental data, based on the coefficient of determination (R2= 0.991), mean relative percent error (MRE=15.019), and standard error of estimation (SEE=1.371). Besides, multilayer perceptron model with four layers (2: 17: 14: 1) was selected as the best artificial neural network for estimation of onion slices’ equilibrium moisture content by considering R2= 0.993 and good performance. The net isosteric heat of adsorption of moisture was determined by applying the Clausius–Clapeyron equation to the sorption isotherms at different temperatures. The net isosteric heat of adsorption of red onion slices varied between 1.46 and 4.96 kJ/mol at moisture content varying between 2% and 52% (d.b.).

scholarly journals MODELING DYNAMIC ADSORPTION ISOTHERMS AND THERMODYNAMIC PROPERTIES OF SPECIALTY GROUND ROASTED-COFFEE (Coffee Arabica L.)

2019 ◽  
Vol 14 (1) ◽  
pp. 93 ◽  
Author(s):  
Gentil Andres Collazos-Escobar ◽  
Nelson Gutiérrez-Guzman ◽  
Henry A. Vaquiro Herrera
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Adsorption Isotherms ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Roasted Coffee ◽  
Sorption Data ◽  
Specialty Coffee ◽  
Sensorial Attributes

Specialty coffee is highly differentiated product because of  its sensorial attributes: aroma, body and brand reputation. In specialized markets, these products are highly valued, and sometimes up to six times their commercial value is paid. Thus, it is essential to preserve their freshness. Sorption isotherms are necessary for determining and studying water sorption changes in specialty coffee during storage. This study aimed to determine the adsorption isotherms of specialty ground roasted-coffee at temperatures of 25 °C, 30 °C and 40 °C and water activities between 0.1 and 0.8 using the dynamic dewpoint method (DDI). The experiment sorption data were modeled using 12 different equations with non-linear regression to represent the dependence of the equilibrium moisture content with both water activity and temperature. In addition, the thermodynamic properties were determined with the experiment adsorption data. The results showed that type III isotherms were obtained according to the Brunauer classification, and the Weibull equation satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in the specialty ground roasted-coffee. The results of thermodynamic analysis showed that the net isosteric heat of adsorption and Gibbs free energy decreased as the equilibrium moisture content increased, indicating the amount of energy released, a strong bond energy between water molecules in the product components and spontaneity in the adsorption process. The entropy of the adsorption increased with the moisture content, leading to product stability conditions during storage. The results were similar to those reported for the roasted and ground coffee of others cultivars.

Moisture Sorption Isotherms and Net Isosteric Heats of Sorption of Green Soybean

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Zhao Yang ◽  
Enlong Zhu ◽  
Zongsheng Zhu
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Sorption Capacity ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Model Parameters ◽  
Desorption Process ◽  
Moisture Sorption Isotherms

Abstract Moisture sorption isotherms of green soybean seeds were determined by static gravimetric method and water activity ranging from 0.11to 0.94 at 20, 30 and 40°C. The optimal sorption model of green soybean was determined by using nonlinear regression method. Modified BET multilayer sorption theory model parameters at different temperatures were calculated, isosteric sorption heat was derived by the water activity sorption isosteric model. Results indicated that sorption isotherms were belong to type III behaviour, a notable hysteresis effect was observed, Green soybean monolayer saturated sorption capacity was greater in desorption process than that of adsorption. The monolayer saturated sorption capacity decreased with increasing temperature, while the number of multilayer had a reverse trend with the monolayer saturated sorption capacity, the optimal sorption isotherm model for green soybean is Halsey model, The thermodynamic parameters including net isosteric heat of adsorption and desorption calculated at 40°C were 105.2-1865.4 kJ/kg and 111.62-1939.0 kJ/kg with equilibrium moisture content between 5% and 32% (d.b.), respectively. The net isosteric heat of sorption decreased with increasing equilibrium moisture content.

scholarly journals Desorption isotherms and isosteric heat of araticum (Annona crassiflora Mart.) seeds

2020 ◽  
Vol 24 (9) ◽  
pp. 630-636
Author(s):  
Weder N. Ferreira Junior ◽  
Osvaldo Resende ◽  
Kelly A. de Sousa ◽  
Melícia I. A. Gavazza ◽  
Juliana de F. Sales ◽  
...  
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Nonlinear Regression ◽  
Regression Models ◽  
Information Criterion ◽  
Isosteric Heat ◽  
Nonlinear Regression Models ◽  
Desorption Isotherms ◽  
Annona Crassiflora ◽  
Content Range

ABSTRACT The objective of this study was to determine the desorption isotherms and isosteric heat of Annona crassiflora Mart. seeds, using Akaike information criterion (AIC) and Schwarz’s Bayesian information criterion (BIC) to assist in the choice of the nonlinear regression model. The desorption isotherms were determined by indirect static method and water activity was obtained using the instrument HygroPalm; the product was put in the device in B.O.D. chamber set at 10, 20, 30 and 40 °C. Several nonlinear regression models were fitted to the experimental data by the Gauss-Newton method. The desorption isotherms of Annona crassiflora Mart. seeds can be represented by the models of Chung-Pfost, Copace, Modified GAB, Modified Henderson, Modified Oswin, Sabbah and Sigma Copace. However, the Sigma Copace model showed better fit to the experimental data, with lower AIC and BIC values, being chosen to represent the desorption isotherms of Annona crassiflora Mart seeds. Isosteric heat increased with decreasing moisture content, requiring a greater amount of energy to remove water from seeds, with values ranging from 2541.64 to 2481.56 kJ kg-1, for the moisture content range from 5.69 to 14.93% on a dry basis.

scholarly journals Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits

2017 ◽  
Vol 21 (4) ◽  
pp. 285-289
Author(s):  
Daniel E. C. de Oliveira ◽  
Osvaldo Resende ◽  
Lílian M. Costa ◽  
Glicélia P. Silva ◽  
Juliana de F. Sales
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Dynamic Method ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Coefficient Of Determination ◽  
Chi Square ◽  
Mean Error ◽  
Technological Information ◽  
Desorption Isotherms

ABSTRACT ‘Sucupira-branca’ (Pterodon emarginatus Vogel) is a tree from ‘Cerrado’ and stands out mainly for its pharmacological properties; however, there are no technological information about its post-harvest operations. Thus, the aim of this study was to determine the sorption isotherms of ‘sucupira-branca’ fruits for different air conditions and obtain the values of desorption isosteric heat, depending on the equilibrium moisture content of the product. The equilibrium moisture content of ‘sucupira-branca’ fruits was determined by dynamic method for temperatures of 25, 30, 35 and 40 °C and water activities for each temperature between 0.270 and 0.775. The models Chung-Pfost, Copace, Modified Halsey, Oswin Modified and Sigma Copace obtained high coefficient of determination (R2) and low chi-square (χ2), relative mean error (P) and estimated mean error (SE), and the Copace model was selected to represent the desorption isotherms. The isosteric heat increases with the reduction of equilibrium moisture content and required more energy to remove water from the ‘sucupira-branca’ fruit.

scholarly journals Desorption isotherms and isosteric heat of 'cajuzinho-do-cerrado' achenes

2016 ◽  
Vol 20 (5) ◽  
pp. 481-486 ◽  
Author(s):  
Karine F. Barbosa ◽  
Juliana de F. Sales ◽  
Osvaldo Resende ◽  
Daniel E. C. de Oliveira ◽  
Jacson Zuchi ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
National Park ◽  
Linear Regression Analysis ◽  
Isosteric Heat ◽  
Static Method ◽  
Different Temperatures ◽  
Desorption Isotherms ◽  
The One ◽  
Content Range

ABSTRACT The objective of this study was to determine the desorption isotherms of 'cajuzinho-do-cerrado' achenes (Anacardium humile St. Hil.) in various conditions of temperature and water activity, as well as to select the one that best represents the phenomenon and to determine the isosteric heat of desorption. The fruits were collected at the Emas National Park, in the municipality of Mineiros-GO, Brazil, pulped and then subjected to drying in silica gel at temperature of 25 ± 2 °C until the moisture contents of 17.6, 13.6, 11.1, 8.7 and 5.3 (d.b.%). After drying, the desorption isotherms were determined by the indirect static method. The water activity (Aw) was determined at different temperatures, and the achenes were placed in a B.O.D. chamber, regulated at 10, 20, 30 and 40 °C. Data of hygroscopic equilibrium moisture content were fitted to different mathematical models through non-linear regression analysis, using the Gauss-Newton method. The Copace model was the one that best represented the hygroscopicity of 'cajuzinho-do-cerrado' achenes, while the integral isosteric heat of desorption of 'cajuzinho-do-cerrado' achenes for the moisture content range of 4.51 to 13.40 (% d.b.) varied from 2,734.82 to 2,548.49 kJ kg-1.

scholarly journals Modeling sorption isotherms and isosteric heat of sorption of roasted coffee beans

2018 ◽  
Author(s):  
Gentil Andres Collazos-Escobar ◽  
Nelson Gutiérrez-Guzmán ◽  
Henry Alexander Vaquiro-Herrera ◽  
Erika Tatiana Cortes-Macias
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Dew Point ◽  
Roasted Coffee ◽  
Sorption Data ◽  
Heat Of Sorption ◽  
Coffee Beans ◽  
Roasted Coffee Beans

The aim of this work was determine the sorption isotherms in roasted beans of specialty coffee at temperatures of 25, 30 and 40 °C and water activities between 0.1 and 0.8 using the dynamic dew point method. The experimental sorption data were modeled using 12 different equations to represent the dependence of equilibrium moisture content with aw and temperature. The net isosteric heat of sorption was determined from the experimental sorption data using the Clausius-Clapeyron equation. The Weibull model satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in roasted coffee beans (R2adj =0.902 and RMSE = 0.00550 kg·kg-1d.b.). The net isosteric heat of sorption increase with increased moisture content. Keywords: water activity; sorption properties; equilibrium moisture content; hygroscopicity

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