scholarly journals Application of Dynamic Temperature-Humidity Chamber for Measuring Moisture Sorption Isotherms of Biomaterials as Compared to the Conventional Isopiestic Method

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Maha Al-Khalili ◽  
Nasser Al-Habsi ◽  
Mohammad Shafiur Rahman
Keyword(s):  
Water Activity ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isopiestic Method ◽  
Model Parameters ◽  
Dynamic Temperature ◽  
Water Sorption Isotherm ◽  
State Of Water ◽  
Moisture Sorption Isotherms ◽  
Humidity Chamber

Measurement of water activity and moisture sorption isotherms of foods and biomaterials are important to determine the state of water. In this work, a dynamic temperature-humidity (DTH) controlled chamber was used to measure water sorption isotherm and compared with the conventional isopiestic method. Temperature and relative humidity of DTH chamber can be controlled in the range of -15 to 100°C and 0 to 98%, respectively; thus, measurement of water activity at any point can be measured within the above ranges. The DTH chamber method showed high reproducibility as compared with the conventional isopiestic method when measured isotherms of cellulose, lignin, and hemicellulase were compared at 30°C. Finally, isotherm data of cellulose, lignin, and hemicellulase were generated in the temperature range of 10-90°C using DTH chamber, and these were modelled by BET and GAB equations. The model parameters were correlated with the temperature.

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 Moisture Sorption Behaviour and Mould Ecology of Trade Garri Sold in South Eastern Nigeria

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Tochukwu Samuel ◽  
J. Obeta Ugwuanyi
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Central Africa ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Fungal Species ◽  
Temperature Dependent ◽  
Sorption Behaviour ◽  
Moisture Sorption Isotherms ◽  
West And Central Africa

Garri is a creamy white or yellow starchy grit produced by roasting to gelatinization and dryness of peeled, washed, mashed, and fermented dewatered cassava roots. It is the most important product of cassava in West and Central Africa. Mean moisture content of yellow and white garri was 11.11% and 10.81% within 24 hrs of sampling from the market, increasing to 17.27% and 16.14%, respectively, following 3 months of storage at room temperature. The water activity of samples varied from initial 0.587 to 0.934 following storage. Moisture sorption isotherms, determined by static gravimetric techniques at 20° and 30°C, showed temperature dependent BET Sigmoidal type II behaviour typical of carbohydrate rich foods but modulated very slightly by the content of palm oil. Equilibrium moisture content decreased with increase in temperature at constant water activity. A total of 10 fungal species belonging to the generaMucor,Penicillium,Cephalosporium,Aspergillus,Scopulariopsis,Rhizopus, and Paecilomyceswere identified, with range increasing with water activity of samples.

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.

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.

Experimental Study and Modelling of Moisture Sorption Isotherms of Salted Largehead Hairtail (Trichiurus lepturus) at 25 and 35°C

2014 ◽  
Vol 1033-1034 ◽  
pp. 681-689
Author(s):  
Zhong Yang Ren ◽  
Yan Yan Wu ◽  
Zhen Hua Duan ◽  
Lai Hao Li ◽  
Xian Qing Yang
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
The Body ◽  
Trichiurus Lepturus ◽  
Moisture Sorption Isotherms

The moisture sorption characteristics of salted largehead hairtail (Trichiurus lepturus) were investigated within the limits of water activity (0.11-0.98) at 25 and 35°C using a self-made instrument for the measurement of the equilibrium moisture content according to the static gravimetric method. The shape of the sorption isotherms was sigmoidal. The moisture sorption isotherms exhibited significant hysteresis. The hysteresis of salted fish may be due to the salt permeating into the body of the fish as a result of desorption and adsorption processes. Seventeen mathematical models were fit to the experimental data for the equilibrium moisture content at different water activity levels. The Ferro-Fontan equation provided the best fit for the experimental data of the equilibrium moisture content among the 17 models assessed for the sorption isotherms at 25 and 35°C. The net isosteric heats of sorption decreased gradually with increases in moisture content. The isosteric heats of sorption ranged from 44.59 kJ/mol to 45.61 kJ/mol between the moisture contents of 22.22% and 43.25% for salted largehead hairtail.

scholarly journals Experimental Investigation of Moisture Sorption Isotherms for Mefenamic Acid Tablets

2020 ◽  
Vol 21 (4) ◽  
pp. 11-20
Author(s):  
Maha Muhyi Alhussaini ◽  
Hassanain A. Hassan ◽  
Nada S. Ahmedzeki
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Mefenamic Acid ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Sorption Process ◽  
Sorption Behavior ◽  
Moisture Sorption Isotherms ◽  
Gab Model ◽  
Monolayer Moisture

   The moisture sorption isotherms of Mefenamic acid tablets were investigated by measuring the experimental equilibrium moisture content (EMC) using the static method of saturated salt solutions at three temperatures (25, 35, and 45°C) and water activity range from 0.056 to 0.8434. The results showed that EMC increased when relative humidity increased and the sorption capacity decreased, the tablets became less hygroscopic and more stable when the temperature increased at constant water activity. The sorption curves had a sigmoid shape, type II according to Brunauer’s classification. The hysteresis effect was significant along with the whole sorption process. The results were fitted to three models: Oswin, Smith, and Guggenhein - Anderson and de Boer. According to the fitting results, the GAB model was the most appropriate model to describe the sorption behavior of Mefenamic acid; it had a regression coefficient range (0.9803-0.994), %E (0.69-4.06), and low values of SEE (0.85-2.2). The monolayer moisture content was calculated using the GAB model and it was concluded that the tablets should be stored at moisture content equal or slightly higher than (0.2046, 0.1843, and 0.1437 %) for desorption and (0.2073, 0.1269, and 0.1452 %) for adsorption for the three temperatures.

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