Adsorption–desorption isotherms and heat of sorption of prickly pear fruit (Opuntia ficus indica) (original) (raw)
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Journal of Food Engineering, 2002
Moisture equilibrium data for adsorption and desorption of water from prickly pear peel (Opuntia ficus indica) were investigated at temperatures in the range of 30-50°C and water activity ranging from 0.05 to 0.9. The experimental procedure used was based on the gravimetric static method. The experimental curves of sorption are then described by GAB, Henderson's and BET models. The BET and Henderson models were found to be the most suitable for describing the sorption curves. The monolayer moisture content values for the sorption at different temperature are calculated.
Energy Conversion and Management, 2003
The equilibrium moisture contents of cladode of Opuntia ficus indica were determined using the gravimetric static method at 30, 40 and 50°C over a range of relative humidity (Rh) from 0.05 to 0.9. The sorption capacity of cladode decreased with increase in temperature at constant Rh. The experimental sorption curves are then described by the GAB, Henderson's and BET models. The BET model was found to be the most suitable for describing the sorption curves. The monolayer moisture content values for the sorption at different temperatures are calculated.
Searching the most optimal model of water sorption fruit powder
The present work aims to investigate the moisture adsorption characteristics of Lyophilized Algerian Arbutus unedo L. fruit powder (LP). First, the LP was evaluated for some of its physicohemical parameters, including X-ray diffraction (XRD) properties, crude fiber, titrable, etc. Second, the experimental sorption curves, determined at 20, 30 and 40 °C with the standard static-gravimetric method, were fitted to six isotherm models (Kühn, Caurie, Smith, Halsey, Oswin and GAB). Results showed also that the moisture adsorption isotherms of LP are of Sshaped profile (Type II), generally obtained for biomaterials. Among all tested models, those of Halsey and GAB (T=20 and 30 °C) gave the best fits at 20 and 30 °C, with the mean relative percentage deviation modulus (E%) less than 1%, χ 2 ≤ 2.68 10 -1 and a root mean square error (RMSE) ≤ 0.2808). The K parameter of GAB model was found to increase with increasing temperature, whereas the monolayer moisture content (X 0 ) decreased with increasing temperature. Such data are represent a usefull tool for choose appropriate storage conditions of LP.
ADSORPTION ISOTHERMS OF PEAR AT SEVERAL TEMPERATURES by
2016
The moisture adsorption isotherms of pear were determined at 15 °C, 30 °C, and 45i°C using the standard static gravimetric method over a range of water activity from 0.112 to 0.920. The experimental data were fitted with isotherm equations recommended in ASAE Standard D245.5. In order to find which equation gives the best results, large number of numerical experiments were performed. After that, several statistical criteria proposed in scientific literature for estimation and selec-tion of the best sorption isotherm equations were used. For each equation and ex-perimental data set, the average performance index was calculated and models were ranked afterwards. After that, some statistical rejection criteria were checked (D'Agostino-Pearson test of normality, single-sample run test and significance and precision of the model parameters). The performed statistical analysis shows that the Guggenheim-Anderson-de Boer equation has the highest value of average per-formance index, but...
Adsorption isotherms of pear at several temperatures
Thermal Science, 2014
The moisture adsorption isotherms of pear were determined at 15°C, 30°C, and 45i°C using the standard static gravimetric method over a range of water activity from 0.112 to 0.920. The experimental data were fitted with isotherm equations recommended in ASAE Standard D245.5. In order to find which equation gives the best results, large number of numerical experiments were performed. After that, several statistical criteria proposed in scientific literature for estimation and selection of the best sorption isotherm equations were used. For each equation and experimental data set, the average performance index was calculated and models were ranked afterwards. After that, some statistical rejection criteria were checked (D'Agostino-Pearson test of normality, single-sample run test and significance and precision of the model parameters). The performed statistical analysis shows that the Guggenheim-Anderson-de Boer equation has the highest value of average performance index, but higher correlation between pair of parameters leads to lower precision of estimated parameters.
Moisture sorption isotherms of mango slices
Moisture sorption isotherms (desorption and adsorption) of mango fruit, var. Kent, were investigated using the standard static gravimetric method. The sorption isotherms were obtained at the temperatures of 20, 30 and 40 °C and in the water activity (a w ) range from 0.111 to 0.813. The sorption isotherms of mango fruit followed type III (J-shaped) isotherms, characteristic of high sugar products. The reverse temperature effect occurred at a w >0.75, resulting in a crossing over of the sorption curves for the adsorption isotherms only. The application of the GAB model to the experimental data, using direct nonlinear regression analysis, provided agreement between the experimental and predicted values. The GAB model parameters monolayer moisture content (Mo) and heat of sorption for monolayer (C) were found to decrease with increasing temperature, whereas the heat of sorption for multilayer (K) was found to increase with increasing temperature. A hysteresis effect was observed at all three temperatures studied.
Journal de Physique IV (Proceedings), 2004
This work is focused on some properties of dried apple (Red Chief) and carrot (Misky). Water sorption isotherms of carrot and apple were investigated at three temperatures: 30, 40 and 60°C, corresponding to drying temperatures, by the static method consisting of the use of different sulphuric acid solutions. Guggenheim-Anderson-de Boer (G.A.B) model is found to describe the experimental curves better than Henderson, Hasley and Oswin models with a correlation coefficient superior to 0.97 for both products. The hysteresis phenomenon was clearly observed in the case of apple isotherms. The experimental data were also used to determine the isosteric enthalpy of desorption of apple and carrot. The isosteric enthalpy of desorption decreased with increase in moisture content and the trend became asymptotic.
Moisture adsorption characteristics of solar-dried mango slices (p883-890)
Moisture adsorption isotherms of solar-dried mango slices (cv. Kitchener) were determined at three temperatures (20°C, 30°C and 40°C) for a water activity (a w ) range of 0.111 to 0.813 using the standard static gravimetric method. The sorption characteristic of solar-dried mango slices followed type III (J-shaped) isotherms, characteristic of high sugar products. An intersection of the curves occurred at a w =0.75 for the investigated temperatures, which indicates the occurrence of the reverse temperature effect. The experimental equilibrium moisture content data were subsequently fitted to two well-known mathematical sorption models; namely, the BET and GAB models. Non-linear regression analysis was used to evaluate the models' parameters. The validation of the two selected models was done by using statistical parameters: the mean relative percentage deviation (% P) and the coefficient of determination (R 2 ). The estimated parameters of the GAB model were correlated to temperature. The (K) parameter of GAB model was found to increase with temperature, whereas the monolayer moisture content (Mo) decreased with increasing temperature. The Arrhenius-type relationships of the GAB parameters were determined. The GAB model was satisfactorily used to predict the equilibrium moisture content (EMC) of solar dried-mango slices.
Sorption isotherms and moisture sorption hysteresis of intermediate moisture content banana
Journal of Food Engineering, 2008
Sorption isotherms of dried or intermediate moisture content (IMC) products are most important to model moisture uptake during storage and distribution. Working isotherms of IMC bananas were determined at five different temperatures (10, 15, 20, 30 and 40°C). Desorption and adsorption isotherms were determined at 10 and 40°C. All the sorption curves were found to be Type II, with non-zero moisture content (approximately 3-9% db for different temperatures) when the water activity was zero. Different models were fitted to the data and it was found that the best results were obtained with a modified Freundlich equation (valid from 0.06 to 0.76 water activity). The dependence of the models constants on temperature was investigated and the secondary models were built accounting for the effect of a w and temperature on the samples moisture content (R 2 = 99%). Hysteresis was observed at 10°C and 40°C, but the effect was greater at 10°C. The net isosteric heat of sorption (working isotherms) varied from 0.85 kJ g À1 mol À1 to 7.67 kJ g À1 mol À1 , decreasing with increasing moisture content. This effect was well described by an exponential function (R 2 > 99%). These results provide reliable experimental data on sorption isotherms which is important for designing an optimized packaging system.