scholarly journals Sorption isotherms for oat flakes (Avena sativa L.)

2014 ◽  
Vol 32 (1) ◽  
pp. 52-58 ◽  
Author(s):  
José Edgar Zapata M. ◽  
Oscar Albeiro Quintero C. ◽  
Luis Danilo Porras B.
Keyword(s):  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Conditions ◽  
Percentage Error ◽  
Relative Air Humidity ◽  
Moisture Sorption Isotherms ◽  
Relative Percentage Error ◽  
The Mean ◽  
Best Fit

Moisture sorption isotherms of oat flakes were determined at temperatures of 5, 25 and 37°C, using a gravimetric technique in an aw range of between 0.107 and 0.855. These curves were modeled using six equations commonly applied in food. The quality of the fit was assessed with the regression coefficient (r2) and the mean relative percentage error (MRPE). The best fit were obtained with the Caurie model with r2 of 0.996, 0.901 and 0.870, and MRPE of 7.190, 17.878 and 16.206, at 5, 25 and 37°C, respectively. The equilibrium moisture presented a dependence on temperature in the studied aw range, as did the security moisture (XS). These results suggest that the recommended storage conditions of oat flakes include: a relative air humidity of 50% between 5 and 25°C and of 38% up to 37°C.

Moisture Sorption Isotherms and Isosteric Heats of Sorption of High-Pressure Treated Paulownia Wood under Different Storage Conditions

2019 ◽  
Vol 62 (1) ◽  
pp. 105-114
Author(s):  
Xiuping Jiang ◽  
Xiuping Jiang ◽  
Huanhuan Li ◽  
Hosahalli S. Ramaswamy ◽  
Songming Zhu ◽  
...  
Keyword(s):  
High Pressure ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Conditions ◽  
Sorption Behavior ◽  
Adsorption And Desorption ◽  
Moisture Sorption Isotherm ◽  
Moisture Sorption Isotherms ◽  
Paulownia Wood

Abstract. Understanding of moisture sorption isotherms (MSI) is critical for predicting the stability of wood during handling, transport, and storage. The aim of this study was to evaluate the adsorption and desorption isotherm characteristics of high-pressure (HP) treated paulownia wood and to identify the best-fitting model to describe its sorption behavior. The equilibrium moisture contents (EMCs) of HP-treated paulownia wood were obtained using a static gravimetric method under different storage conditions: three temperatures (20°C, 30°C, and 40°C) and five water activity (aw) levels (0.32 to 0.95). Results showed that HP parameters did not significantly affect the MSI trend of treated groups. Eight modified models (modified Chung-Pfost, modified Henderson, modified Oswin, modified Halsey, Chen-Clayton, Guggenheim-Anderson-de Boer (GAB), simply modified GAB, and Peleg) were fitted to the experimental data. The Chen-Clayton model (temperature-dependent) produced randomized residuals and the best prediction performance for both adsorption and desorption among all models. Net isosteric heat of adsorption and desorption decreased from 7.55 to 4.84 kJ mol-1 and from 18.1 to 12.2 kJ mol-1, respectively, with an increase in EMC from 7.5% to 10%. The isosteric temperature (Tß) was 352 K for adsorption and 335 K for desorption, between which all the adsorption and desorption reactions proceeded at the same rate. All thermodynamic functions were adequately characterized by a power law model. Keywords: Equilibrium moisture content, High-pressure treatment, Modeling, Moisture sorption isotherm, Paulownia wood, Temperature, Thermodynamic analysis.

scholarly journals Moisture Sorption Isotherms And Thermodynamic Properties Of Urtica Dioica Leaves

2016 ◽  
Vol 12 (24) ◽  
pp. 376 ◽  
Author(s):  
Abdelkader Lamharrar ◽  
Ali Idlimam ◽  
Mohammed Kouhila ◽  
Lamya Lahnine ◽  
Hind Mouhanni
Keyword(s):  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Conditions ◽  
Urtica Dioica ◽  
Endemic Plant ◽  
Clapeyron Equation ◽  
Moisture Sorption Isotherms ◽  
Different Temperatures

Urtica dioica is a Moroccon endemic plant of used for its virtues in traditional medicine. Thus, it is necessary to study the effect of preservation processes on the storage conditions of the plant. The static gravimetric method was used to determine sorption isotherms of Urtica dioica leaves at three temperatures (40, 50 and 60 °C) and in the range of water activity ( w a ) ranging from 0.0572 to 0.898. Six mathematical models were used to fit the experimental data. The Enderby and Peleg models were found to be the most suitable for describing the sorption curves. The optimal water activity for conservation of Urtica dioica leaves was determined. Isosteric heats of desorption and adsorption were calculated by applying the Clausius- Clapeyron equation to the sorption isotherms at different temperatures; it decreased with increasing moisture content. A linear relation exists between the enthalpy and entropy of the sorption reaction.

scholarly journals Effect of temperature on moisture sorption phenomena in agricultural products

2005 ◽  
Vol 53 (4) ◽  
pp. 177-184 ◽  
Author(s):  
Jiří Štencl
Keyword(s):  
Water Activity ◽  
Dynamic Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Effect Of Temperature ◽  
Relative Air Humidity ◽  
Introductory Part ◽  
Moisture Sorption Isotherms ◽  
Model Equations ◽  
Dehydration Processes

The paper demonstrates importance of temperature influence on dehydration processes using drying model equations in introductory part and further presents results of water sorption tests of parsley leaves. Measurements were carried out under laboratory conditions in the temperature range of 10–40 °C and relative air humidity from 30 to 100%. Moisture sorption isotherms were tested using a gravimetric dynamic method with continuous recording of changes in sample weight. Five mathematical models available in the literature (Chung-Pfost, GAB, Halsey, Henderson, and Oswin) were statistical evaluated. The Henderson equation was found to be a good model both for moisture adsorption and desorption. Part of the sorption isotherms measured in parsley leaves show the type II BET classification shape. An increase in temperature causes an increase in water activity for the same moisture content and, if water activity is kept constant, an increase in temperature causes a decrease in the amount of absorbed water.

scholarly journals Moisture Sorption Isotherms and Prediction Models of Carboxymethyl Chitosan Films from Different Sources with Various Plasticizers

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Juthamas Tantala ◽  
Chitsiri Rachtanapun ◽  
Wirongrong Tongdeesoontorn ◽  
Kittisak Jantanasakulwong ◽  
Pornchai Rachtanapun
Keyword(s):  
Water Solubility ◽  
Prediction Models ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
High Water ◽  
Carboxymethyl Chitosan ◽  
Percentage Error ◽  
Moisture Sorption Isotherms ◽  
Gab Model ◽  
The Stability

Carboxymethyl chitosan (CMCH) from different chitosan sources (shrimp, crab, and squid) and molecular sizes (polymer and oligomer) were synthesized via carboxymethylation reaction. The CMCH films were prepared by solution casting. All the CMCH films had high water solubility, higher than 85% of the dry matter of the films. The sorption isotherm of the CMCH films was evaluated at several values of relative humidity (0% RH, 23% RH, 34% RH, 43% RH, 65% RH, 77% RH, and 86% RH) at 25 ± 1°C. The equilibrium moisture content values of all the CMCH films were low at lower aw but increased considerably above aw = 0.65. The sigmoidal moisture sorption isotherms of this product can be classified as type II. Understanding of sorption isotherms is an important prerequisite for the prediction of moisture sorption properties of films via moisture sorption empirical models. The experimental data were analyzed and fitted by the nine sorption models. The various constants determined by linear fitting of the sorption equation with r2 values were in the range of 0.7647 to 0.999. The GAB model was found to be the best-fitted model for CMCH films (aw = 0.23–0.86, 25 ± 1°C), and the model presented the optimal root-mean-square percentage error (%RMS) values when compared with other models. In conclusion, it can be stated that the GAB model was found to be better estimated for predicting the CMCH films than other models. Therefore, the constant derived from different sorption models were applied for use in terms of information and for the determination of the stability of CMCH packaging films for specific end uses.

Prediction Modeling for Moisture Sorption Isotherms of Rice Starch/Carboxymethyl Cellulose from Durian Rind Blend Films

2013 ◽  
Vol 431 ◽  
pp. 32-36 ◽  
Author(s):  
Rungsiri Suriyatem ◽  
Pornchai Rachtanapun
Keyword(s):  
Sorption Isotherm ◽  
Carboxymethyl Cellulose ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Rice Starch ◽  
Percentage Error ◽  
Blend Films ◽  
Moisture Sorption Isotherm ◽  
Moisture Sorption Isotherms ◽  
Durian Rind

Rice starch/carboxymethyl cellulose from durian rind (RS/CMCd) blend films were prepared by solution casting. The effect of different ratios between rice starch and CMCd (100:0, 88:12, 67:33, 50:50, 33:67, 12:88 and 0:100) on moisture sorption isotherm of blend films was investigated. The sorption isotherm of RS/CMCd blend films was determined at various relative humidity (RH) at 25°C. The isotherm curves revealed that the highest equilibrium moisture content (EMC) was obtained from CMCd film, at aw=85. Knowledge of sorption isotherms is important to predict the moisture sorption properties of the filmsviamoisture sorption empirical models. The Lewicki, Peleg, Guggenheim-Anderson-deBoer (GAB), BrunauerEmmettTeller (BET), and Oswin models were tested to fit the experimental data. The root mean squares percentage error (%RMS) of Lewicki, Peleg, GAB, BET and Oswin was in the range of 5.3-83.1, 2.2-20.0, 6.9-20.2, 3.4-26.4 and 4.7-41.2, respectively. The Peleg model was found to be the best fitted model for RS/CMCd blend films.

Determination of Moisture Sorption Isotherms of Jasmine Rice Crackers Using BET and GAB Models

2006 ◽  
Vol 12 (6) ◽  
pp. 459-465 ◽  
Author(s):  
U. Siripatrawan ◽  
P. Jantawat
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Sorption Data ◽  
Heat Of Sorption ◽  
Moisture Sorption Isotherms ◽  
Jasmine Rice ◽  
Gab Model ◽  
Best Fit

Moisture sorption isotherms of Thai Jasmine rice crackers were determined at 30, 45 and 60°C over a water activity range of 0.10 to 0.95 using a static gravimetric technique. Moisture sorption isotherms of rice crackers exhibited the sigmoid (Type II) shape. The moisture content of rice crackers decreased as temperature increased at a given water activity of the storage environment. The Brunauer, Emmett and Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models were applied to fit the experimental data. The isosteric heat of sorption at different moisture levels was also determined using the Clausius–Clapeyron thermodynamic equation. A nonlinear regression analysis method was determined to evaluate the parameters of sorption equations. The criteria used to evaluate the goodness of fit of each model were the mean relative percentage deviation modulus (E) and the percentage root mean square error (RMSE). The more extended range of application of the GAB equation over the BET equation was evident. The GAB model gave the best fit to the experimental sorption data for a wide range of water activity (0.10–0.95) while the BET model gave the best fit for a water activity range of less than 0.60. The GAB model is considered suitable to predict the moisture sorption isotherm of rice crackers since it gave low E and RMSE values. The heat of sorption values of rice crackers were found to be large at low moisture content and decreased with an increase in food moisture content.

Note: Moisture Sorption Isotherms and Isosteric Heat of Red Bell Pepper (var. Lamuyo)

2007 ◽  
Vol 13 (4) ◽  
pp. 309-316 ◽  
Author(s):  
A. Vega-Gálvez ◽  
R. Lemus-Mondaca ◽  
P. Fito ◽  
A. Andrés
Keyword(s):  
Statistical Evaluation ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Sorption Data ◽  
Clapeyron Equation ◽  
Moisture Contents ◽  
Moisture Sorption Isotherms ◽  
Monolayer Moisture

Sorption isotherms of red pepper (var. Lamuyo) were determined at three temperatures (10, 20 and 30°C) in a range of water activity from 0.10 to 0.96. BET, GAB, Halsey, Herderson, Caurie, Smith, Oswin and Iglesias—Chirife equations were tested for modelling the sorption isotherms. The statistical evaluation of fit quality of the preceding models showed good results using the BET, GAB, Halsey and Iglesias—Chirife models on experimental sorption data. The BET and GAB models showed monolayer moisture contents from 0.07 to 0.10 g water/g (d.b.); however, they did not show direct dependence on temperature. The Clausius—Clapeyron equation satisfactorily determined the sorption isosteric heats, which were found to increase as the moisture content decreased; the desorption heat (74.2kJ/mol) was higher than that of adsorption heat (36.9kJ/mol). The preceding experimental data showed a good quality fit when evaluated with the Tsami equation.

scholarly journals Simulation of Storage Conditions of Mixed Biomass Pellets for Bioenergy Generation: Study of the Thermodynamic Properties

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2544
Author(s):  
Lyes Bennamoun ◽  
Merlin Simo-Tagne ◽  
Macmanus Chinenye Ndukwu
Keyword(s):  
Mathematical Modeling ◽  
Thermodynamic Properties ◽  
Standard Error ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Conditions ◽  
Coefficient Of Determination ◽  
Chi Square ◽  
Bioenergy Generation ◽  
Moisture Sorption Isotherms

Experimental and mathematical modeling of the moisture sorption isotherms for biomass pellets during storage is performed in this study. The tested pellets are a mixture of 50% wood: spruce or pine, and 50% switchgrass agricultural biomass. Storage conditions, i.e., temperature and humidity, are tested by varying the environment conditions in a conditioning chamber. The experimental results show that the moisture sorption isotherms are not affected by the temperature. Nevertheless, the equilibrium moisture content depends on the kind of the tested pellets. Mathematical modeling of the experimental isotherms is performed using four common models: the Oswin, GAB, Henderson and Peleg models. The Oswin model is defined as the most appropriate model to predict the moisture sorption isotherms of the spruce–switchgrass pellets. It presents a coefficient of determination equal to 0.998, a standard error around 0.049 and a chi-square approaching 0.007. On the other hand, Henderson and GAB models show the best results for pine–switchgrass pellets, with a coefficient of determination varying between 0.998 and 0.997, a standard error range 0.054–0.065 and chi-square error between 0.008 and 0.009. The thermodynamic properties, which include the net isosteric of heat and the entropy changes of sorption, are also determined for all tested samples.

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