Hygroscopic proprieties of fig (Ficus carica L.): Mathematical modelling of moisture sorption isotherms and isosteric heat kinetics

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.

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Moisture Sorption Isotherms and Thermodynamic Properties of Carrot

International Journal of Food Engineering ◽

10.2202/1556-3758.1804 ◽

2011 ◽

Vol 7 (3) ◽

Cited By ~ 17

Author(s):

Valeria S. Eim ◽

Carmen Rosselló ◽

Antoni Femenia ◽

Susana Simal

Keyword(s):

Moisture Content ◽

Dry Matter ◽

Sorption Isotherms ◽

Moisture Sorption ◽

Isosteric Heat ◽

Nonlinear Regression Analysis ◽

Mean Relative Error ◽

Moisture Sorption Isotherms ◽

Different Temperatures ◽

Water Sorption Isotherms

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.

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Comparative moisture sorption isotherms, modelling and isosteric heat of sorption of controlled and irradiated Moroccan rosemary leaves

Industrial Crops and Products ◽

10.1016/j.indcrop.2016.02.050 ◽

2016 ◽

Vol 88 ◽

pp. 28-35 ◽

Cited By ~ 11

Author(s):

Safa Mghazli ◽

Ali Idlimam ◽

Mostafa Mahrouz ◽

Lamyae Lahnine ◽

Nadia Hidar ◽

...

Keyword(s):

Sorption Isotherms ◽

Moisture Sorption ◽

Isosteric Heat ◽

Heat Of Sorption ◽

Moisture Sorption Isotherms

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Effect of temperature on the moisture sorption isotherms of a heat-treated whole milk product, khoa

Journal of Dairy Research ◽

10.1017/s0022029900029903 ◽

1991 ◽

Vol 58 (3) ◽

pp. 329-335 ◽

Cited By ~ 13

Author(s):

Ish K. Sawhney ◽

Girdhari R. Patil ◽

Bikram Kumar

Keyword(s):

Sorption Isotherms ◽

Moisture Sorption ◽

Isosteric Heat ◽

Moisture Level ◽

Effect Of Temperature ◽

Milk Product ◽

Heat Treated ◽

Moisture Sorption Isotherms ◽

Monolayer Moisture ◽

Increasing Temperature

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.

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