scholarly journals Experimental Determination and Modeling of the Moisture-Sorption Isotherms and Isosteric Heat of Tobacco Leaves

2021 ◽  
Vol 20 (5) ◽  
pp. 269-277
Author(s):  
Foullanine Meriama ◽  
Bennaceur Said ◽  
Loumani Akil ◽  
Mediani Ahmed ◽  
Moungar Houcine ◽  
...  
Keyword(s):  
Nicotiana Tabacum ◽  
Experimental Determination ◽  
Water Content ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Nicotiana Tabacum L ◽  
Desorption Isotherms ◽  
Adsorption Desorption

During a forced convection sun drying and storage operation, the equilibrium water content of a product to be dried is critical. These figures are frequently derived using isothermal sorption curves. The calculation of isotherms is a necessary step in determining the distribution and intensity of water connections in products. for that this paper concentrates on the experimental determination of the adsorption-desorption isotherms for various temperatures (40, 50, and 60℃) of the Nicotiana Tabacum L plants. From which we had established the relationship between the water activity and the water content in the product. However, the aforementioned determination was carried out by the static gravimetric method. Eight saturated salt solutions have been utilized in applications such as (KOH, KCl, MgCl2, MgNO3, K2CO3, BaCl2, K2SO4, and NaCl). Hygroscopic equilibrium was completed after 13 days for temperature 40℃, 11 days for 50℃, and 9 days for 60℃. The overall experimental sorption curves are summarized by six models (HENDERSON, modified HALSEY, OSWIN, GAB, modified BET, and PELEG). The sorption isotherms built using the Clausius–Clapeyron equation were used to determine the net isosteric temperatures of desorption and adsorption of Nicotiana Tabacum L. The results for the adsorption-desorption isotherms found are type III according to IUAPC. Following the smoothing of the experimental results by different used models, it was found that the models of GAB and Peleg allow having the lowest mean relative errors and correlation coefficient.

Thermodynamic properties of water sorption isotherms of grape seed

2014 ◽  
Vol 28 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Kamran Maleki Majd ◽  
Seyed H. Karparvarfard ◽  
Asgar Farahnaky ◽  
Sara Ansari
Keyword(s):  
Experimental Data ◽  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Grape Seed ◽  
Clapeyron Equation ◽  
Moisture Sorption Isotherm ◽  
Best Fit

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.

scholarly journals APPLICATION OF NEURAL NETWORK FOR ESTIMATION OF PISTACHIO POWDER SORPTION ISOTHERMS

2014 ◽  
Vol 44 (3) ◽  
pp. 189-194
Author(s):  
H. TAVAKOLIPOUR ◽  
M. MOKHTARIAN
Keyword(s):  
Neural Network ◽  
Moisture Content ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isotherm Models ◽  
Ann Modeling ◽  
Moisture Sorption Isotherms ◽  
Artificial Neural Network Ann ◽  
Adsorption Desorption

Moisture sorption isotherms for pistachio powder were determined by gravimetric method at temperatures of 15, 25, 35 and 40ºC. Some mathematical models were tested to measure the amount of fitness of experimental data. The mathematical analysis proved that Caurie model was the most appropriate one. As well, adsorptiondesorption moisture content of pistachio powder were predicted using artificial neural network (ANN) approach. The results showed that, MLP network was able to predict adsorption-desorption moisture content with R2 values of 0.998 and 0.992, respectively. Comparison of ANN results with classical sorption isotherm models revealed that ANN modeling had greater accuracy in predicting equilibrium moisture content of pistachio powder.

scholarly journals Hygroscopicity of baru (Dipteryx alata Vogel) fruit

2017 ◽  
Vol 21 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Daniel E. C. de Oliveira ◽  
Osvaldo Resende ◽  
Lílian M. Costa ◽  
Weder N. Ferreira Júnior ◽  
Silva Igor O. F.
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Equilibrium Moisture Content ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Water Desorption ◽  
Safe Storage ◽  
Moisture Contents ◽  
Desorption Isotherms ◽  
Dipteryx Alata

ABSTRACT With the knowledge on the hygroscopic equilibrium of the baru (Dipteryx alata Vogel) fruit, the product can be adequately handled to maintain the moisture content at the levels recommended for safe storage. Thus, this paper aimed to determine the water desorption isotherms of baru fruits at temperatures of 20, 25, 30 and 35 °C, and water activity between 0.14 and 0.80, and obtain the values of isosteric heat of desorption as a function of the equilibrium moisture content of the product. The equilibrium moisture content was obtained using the static-gravimetric method. Modified Halsey was the best model recommended to represent the hygroscopicity of baru fruits. The recommended moisture contents for safe storage of baru fruits are not more than 19.9, 19.3, 18.6 and 18.0 (%, d.b.) for the respective temperatures of 20, 25, 30 and 35 °C. The integral isosteric heat of desorption increases as the water content decreases, leading to an increment in the energy required to remove water from the product.

scholarly journals Sorption Properties of Some Romanian Gingerbread

2014 ◽  
Vol 18 (1) ◽  
pp. 25-32
Author(s):  
Anca Tulbure ◽  
Mihai Ognean ◽  
Claudia-Felicia Ognean ◽  
Ioan Danciu
Keyword(s):  
Shelf Life ◽  
Water Content ◽  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Condition ◽  
Invert Sugar ◽  
Sorption Properties

Abstract Water activity of gingerbread is very important for keeping the product freshness and shelf life. Water activity is influenced by composition, water content and temperature. The water content of gingerbread could vary according with storage condition. i.e. rH. 11 gingerbread samples were analysed. The water content and water activity lies between 7.0 and 12.6% and respectively 0.590 and 0.715. The sorption isotherms were determined at 30°C by gravimetric method. The moisture sorption is influenced by composition, especially sweeteners and humectants. Honey and invert sugar have the same impact on gingerbread higroscopicity.

Experimental Determination and Modeling of Desorption Isotherms of the Tomato "Lycopersicum esculentum"

2021 ◽  
pp. 24-31
Author(s):  
Roland Lankouande ◽  
G. Gilbert Nana ◽  
Souleymane Ouedraogo ◽  
Kalifa Palm ◽  
Frédéric Ouattara ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Experimental Studies ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Storage Conditions ◽  
Market Place ◽  
Desorption Isotherms ◽  
Final Water Content ◽  
The Stability

The aim of this work is to make a contribution to the drying of tomatoes. The purpose of this contribution is the experimental determination of the desorption isotherms of a variety of tomato (one of the most widespread on the Burkinabe market place) using the static gravimetric method at temperatures of 25°C, 40°C and 50°C. It is more specifically a question of validating a theoretical model based on these experimental studies. Sorption isotherms allow us to have information to establish the stability of food products and their storage conditions. These isotherms are curves which give valuable information on the hygroscopic balance of a product because they allow to know its range of stability after drying by determining the final water content.

scholarly journals Modelling the Water Sorption Isotherms of Warionia Saharae and determination of sorption heats and drying kinetics

2018 ◽  
Author(s):  
Fedol Amel ◽  
A. Cheriti
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Storage Conditions ◽  
Drying Kinetics ◽  
Equilibrium Water Content ◽  
Clapeyron Equation

The hygroscopic equilibrium of Warionia saharae was studied, which allowed getting an idea of ​​the equilibrium water content relative to a given humidity. The results of this study made it possible to have the sorption curves. The results of this study made it possible to obtain the sorption curves necessary for know the storage conditions of the plant and the study of its drying kinetics. The static gravimetric method was used to determine sorption isotherms of Warionia saharae leaves at 30and 40 ◦C and in the range of water activity varying from 0.063 to 0.898.  The Gab, Peleg models was found to be the most suitable for describing the sorption curves. The isosteric heat calculated by applying the Clausius–Clapeyron equation .The desorption isosteric heat was higher than the isosteric heat of adsorption and both decreased continuously with increasing of the equilibrium moisture content. The experimental results obtained allowed us to determine the temporal evolution of the drying kinetics as a function of the moisture content. The curve of the evolution of the water content as a function of time shows the absence of the phases product temperature and constant drying rate Keywords: Sorption isotherm, isosteric heats, modelling, kinetics, Warionia saharae.  

scholarly journals Sorption isotherms and their fitted equations for dried chips of cassava roots (Manihot Esculenta Crantz; Tme-7 variety) and the resulting isosteric heats of sorption

Food Research ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 703-711
Author(s):  
A.S. Ajala ◽  
P.O. Ngoddy ◽  
J.O. Olajide
Keyword(s):  
Relative Humidity ◽  
Shelf Life ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Coefficient Of Determination ◽  
Mean Bias Error ◽  
Isotherm Models ◽  
Bias Error ◽  
Manihot Esculenta Crantz

Cassava roots are susceptible to deterioration with 24 hrs of harvest; it needs processing into a more stable material such as dried cassava chips to extend its shelf life for long storage. However, improper knowledge of the effect of atmospheric relative humidity on these dried chips during storage makes it mouldy and unacceptable. This work aimed at studying the effect of sorption isotherms on the dried cassava chips. In this study, adsorption and desorption isotherm were carried out using static gravimetric method and data for equilibrium moisture content (EMC) were generated at five (5) temperatures (53, 60, 70, 80, 86oC). These were fitted into four (4) isotherm-models [Oswin, Peleg, the Modified Oswin and GAB]. The statistical criteria to test the models were coefficient of determination (R2 ), reduced chi-square (χ 2 ), root mean square error (RMSE) and mean bias error (MBE). The values of EMC ranged from 7.21-12.44% wb. The values of R2 ranged from 0.95-0.99; χ 2 ranged from 0.008-0.14; RMSE values ranged from 0.06-0.254 while MBE values ranged from -0.0004-1.1E-5. The values of isosteric heat of sorption calculated from the isosteres recorded a range from 6.579 to 67.829 kJ/mole. The Pelegmodel gave the best fit in the relative humidity range of 10 to 80%. The values of EMC show that the chips can have a stable shelf life without spoilage.

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.

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