Moisture Sorption Isotherms of Osmotically Dehydrated Sweet Pepper

Author(s):  
Jatindra Kumar Sahu ◽  
Ajita Tiwari

Moisture sorption isotherms of osmotically dehydrated sweet peppers were determined at 15oC, 30oC and 40oC using static desiccator techniques. In the study, seven levels of water activity in range of 0.08 to 0.91 were used by the use of saturated salt solutions. The isotherms were found to be sigmoid type and of BET classification II. Out of seven sorption models i.e. BET, modified BET, Hasley, Caurie, GAB, Oswin and Smith, fitted to the experimental data, Oswin model was found to be the best for accurate prediction of moisture sorption isotherm with highest value of coefficient of determination (R2) and lowest values of standard error (SE) and relative deviation parentage (Rd). The value of monolayer moisture content of the osmotically dehydrated sweet pepper was found to be 3.037%, 3.934% and 4.432% (db) at 15oC, 30oC and 40oC respectively. The values of net isosteric heat of sorption as calculated by Clausius–Clapeyron equation showed a regular fall with increase in moisture content.

2015 ◽  
Vol 11 (4) ◽  
pp. 573-578 ◽  
Author(s):  
Ji-Yeon Chun ◽  
Yeon-Ji Jo ◽  
Jun-Bo Shim ◽  
Sang-Gi Min ◽  
Geun-Pyo Hong

Abstract This study investigated the moisture sorption isotherm (MSI) profiles of freeze-dried (FD) and boiled-dried (BD) abalone at 15°C, 25°C, and 35°C, and compared the quality characteristics of the abalone after rehydration. The equilibrium moisture content (EMC) and the calculated monolayer moisture content of FD abalone were higher than those of BD abalone. After rehydration, FD abalone showed a higher yield and a lower shear force than BD abalone. Additionally, the appearance of FD abalone was similar to that of fresh abalone, reflecting a potential application of FD to produce value-added dried abalone.


2007 ◽  
Vol 13 (4) ◽  
pp. 309-316 ◽  
Author(s):  
A. Vega-Gálvez ◽  
R. Lemus-Mondaca ◽  
P. Fito ◽  
A. Andrés

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.


Molekul ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. 114
Author(s):  
Margareta Novian Cahyanti ◽  
Alvama Pattiserlihun

The moisture sorption isotherm data of gaplek flour fortified with red bead tree seed stored in a chamber, the relative humidity of chamber ranging from 10% to 97% regulated using a saturated salt solution, was determined at three temperatures 25°, 35°, and 45 °C. The experimental data used to determine the thermodynamic functions were isosteric heat of sorption, sorption entropy, and free energy changes. The sorption isosteric heats were determined by the application of the Clausius–Clapeyron equation. Isosteric heats of adsorption increased to maximum level and then declined with increase of moisture content. Adsorption entropy increased to maximum level and then declined with the increase of moisture content. The free energy changes increased with increase in moisture content. The spreading pressure increased with increasing water activity.


Author(s):  
J Roy ◽  
MA Alim ◽  
MN Islam

The study was carried out for the purpose of determining the drying kinetics as well as moisture sorption isotherm of hybrid-81 corn. Corn at about 31% moisture content (wb) was dried in a forced convective hot air cabinet dryer at different drying conditions, such as variable air dry bulb temperature (40°C, 50°C and 60°C) and loading density (3.56 kg/m2, 7.12 kg/m2, and 10.68 kg/m2) as well as in shining sun at different layers (3.56 kg/m2, 7.12 kg/m2, and 10.68 kg/m2). The water sorption isotherm of the dried corn was developed using vacuum desiccators, which contained saturated salt solutions in the range of 11-93% RHs. The mono-layer moisture content calculated by the Brunauer–Emmett–Teller (BET) model (6.76 g/100 g solid) was lesser than that calculated by the Guggenheim–Anderson–De Boer (GAB) model (10.53 g/100 g solid). The energy constants were 10.45 and 4.64 as per BET and GAB equation, respectively. Both models gave suitable fits for corn. The activation energy (Ea) for diffusion of water was found to be 11.09 kcal/gm-mole for corn. Furthermore, it was noticed that, with the increase of corn layer, the drying rate decreased in case of both sun and mechanical drying. However, higher loading density resulted in efficient drying, at least up to 10.7 kg/m2. It was shown that the drying time to obtain stability was the lowest for moisture content (12.08 %) corresponding to aw of 0.65 in case of BET or GAB monolayer moisture content. This finding could be helpful in predicting the storage life of corn.J. Bangladesh Agril. Univ. 15(2): 309-317, December 2017


2014 ◽  
Vol 28 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Kamran Maleki Majd ◽  
Seyed H. Karparvarfard ◽  
Asgar Farahnaky ◽  
Sara Ansari

Abstract In this study the moisture sorption isotherm of grape seed was determined by using a static gravimetric method at 35-65°C and 0.108-0.821 water activity range. The sorption isotherms were found to be typical sigmoid shape of most food materials. Five models including the Brunauer-Emmett-Teller (2-parameter), Guggenheim, Anderson and De Boer (3-parameter), Oswin (2-parameter), Ferro-Fontan (3-parameter) and Peleg (4-parameter) models were considered to fit the experimental data. The Ferro- Fontan and Peleg equations (at three temperatures 35, 45, 65°C) having R2 greater than 0.97 and lower values of standard error of estimate and deviation modulus gave the best fit of the experimental data throughout the entire range of water activity. The net isosteric heat of sorption, calculated by Calusius-Clapeyron equation on experimental data, was found to be a polynomial and exponential function of equilibrium moisture content within the temperature range investigated.


Author(s):  
Zhao Yang ◽  
Enlong Zhu ◽  
Zongsheng Zhu

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.


Author(s):  
Valeria S. Eim ◽  
Carmen Rosselló ◽  
Antoni Femenia ◽  
Susana Simal

The water sorption isotherms of carrot were determined at five different temperatures (at 10, 20, 30, 40 and 50ºC) within wide ranges of moisture content (1.3-78.4 kg water /100 kg dry matter) and water activities (0.165-0.907) by using a standardized conductivity thermohygrometer. The sorption isotherms exhibited the type III behaviour, thus, an increase in temperature promoted a decrease in water activity. The GAB, Halsey, Henderson, Iglesias & Chirife and Oswin models were tested to fit the experimental data by using nonlinear regression analysis. The GAB and Henderson models satisfactorily described the sorption isotherms (mean relative error < 5.6%). The net isosteric heat of sorption (Qstn) and the differential entropy (Sd), estimated as functions of the moisture content, decreased as the carrot moisture content increased.


1991 ◽  
Vol 58 (3) ◽  
pp. 329-335 ◽  
Author(s):  
Ish K. Sawhney ◽  
Girdhari R. Patil ◽  
Bikram Kumar

SummaryMoisture sorption isotherms of khoa were determined at 15, 25, 35 and 45 °C over a water activity (aw) range of O·l 1–0·97. The isotherms were sigmoid (Type II) and were fitted to the Guggenheim–Anderson–de Boer (GAB) equation (Bizot, 1983). The aw of freshly made khoa was found to be 0·96. The aw of khoa increased with increasing temperature up to 0·9; above this the effect of temperature on aw diminished. The monolayer moisture content of khoa decreased with increasing temperature. The equations describing the temperature dependence of GAB constants were determined in the form of the Clausius–Clapeyron equation. The net isosteric heat of desorption of khoa decreased rapidly until a moisture level of 0·1 g/g solids, and approached a constant value of 0·43 kJ/mol above a moisture level of 0·25 g/g solids.


2020 ◽  
Vol 21 (4) ◽  
pp. 11-20
Author(s):  
Maha Muhyi Alhussaini ◽  
Hassanain A. Hassan ◽  
Nada S. Ahmedzeki

   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.


Author(s):  
Mario Luna-Flores ◽  
Mariana Gisela Peña-Juarez ◽  
Angélica Mara Bello-Ramirez ◽  
Javier Telis-Romero ◽  
Guadalupe Luna-Solano

Moisture sorption isotherms of the habanero pepper powder were determined using the Dynamic Vapor Sorption (DVS) method at 20, 25, 35, 45 and 55 °C in a range of water activity from 0.10 to 0.90 at which the processes of drying, packing and storage of habanero pepper are developed. The sorption capacity decreased with increasing temperature at a given water activity and the sorption isotherms showed a sigmoid form (Type II). The hysteresis phenomenon was observed in the sorption isotherms at all temperatures studied and it was more pronounced at temperatures high. The experimental sorption curves were fitting to the GAB, BET and Oswin models. It was concluded that the models that best describe the adsorption and desorption data for habanero pepper dehydrated powder were the GAB and Oswin models.  The isosteric heat of water sorption was calculated with the moisture content data in equilibrium. The desorption isotherms present a higher isosteric heat in relation to the adsorption isotherms. In both, the isosteric heat decreased as the moisture content increased. Keywords: Habanero pepper dehydrated powder; Convective drying; Moisture sorption isotherms; Mathematic models


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