Determination of Moisture Sorption Isotherms of Rice and Husk Flour Composites

2020 ◽  
Vol 36 (6) ◽  
pp. 859-867
Author(s):  
Kaushik Luthra ◽  
Soraya Shafiekhani ◽  
Sammy S. Sadaka ◽  
Griffiths G. Atungulu
Keyword(s):  
Rice Husk ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Rice Flour ◽  
Empirical Models ◽  
Adsorption And Desorption ◽  
Rough Rice ◽  
Moisture Sorption Isotherms ◽  
Rice Husk Flour ◽  
Temperature Levels

HighlightsMoisture sorption isotherms of rice and husk flour composites were determined.Adsorption isotherms were best modeled by the Chung-Pfost and Oswin equations.Desorption isotherms were best modeled by the Polynomial and Chung-Pfost equations.The Modified Oswin model was the best for both adsorption and desorption.Abstract. Empirical models describing isotherms specifically for adsorption and desorption have not been described for rough rice and husk flour composites. Such models are vital for process control and monitoring operations which use rice husk and rice flours or their mixtures for food or material processing. The current study was undertaken to determine the moisture sorption isotherms of rice husk flour, rough rice flour and their mixtures subjected to different temperature levels. Effects of rice husk flour to rough rice flour ratio of 0:1 (0.0%), 1:49 (2.0%), 1:16 (5.9%), and 1:0 g/g (100.0%) on rough rice moisture isotherms at temperature levels of 20°C, 40°C, and 60°C were investigated. The dynamic dewpoint isotherm technique (DDI) was used to generate accurate isotherms. Several empirical models were tested to fit the experimental EMC data. All the isotherms showed typical sigmoidal type 2 shapes. The equilibrium moisture content (EMC) over equilibrium relative humidity (water activity) ranging from 10% to 95% showed temperature dependence. Hysteresis was evident for all samples, with a decreasing level at a higher temperature. Rice husk flour to rough rice flour ratio, as a factor, showed a significant effect on the EMC of rough rice. The EMC decreased with an increase in rice husk flour levels. Chung-Pfost and Oswin were the two best models for describing adsorption isotherm, and Polynomial and Chung-Pfost were the best models for fitting the desorption isotherm. Modified Oswin model was the best model amongst the two-variable models for describing both adsorption and desorption isotherms. Keywords: Empirical models, Equilibrium moisture content, Rice husk flour, Rough rice flour, Sorption isotherms.

scholarly journals Moisture sorption isotherms of castor beans. Part 1: Mathematical modeling and hysteresis

2016 ◽  
Vol 20 (8) ◽  
pp. 751-756 ◽  
Author(s):  
André L. D. Goneli ◽  
Paulo C. Corrêa ◽  
Gabriel H. H. de Oliveira ◽  
Osvaldo Resende ◽  
Munir Mauad
Keyword(s):  
Moisture Content ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Environmental Condition ◽  
Adsorption And Desorption ◽  
Moisture Sorption Isotherms ◽  
Different Temperatures ◽  
The Difference ◽  
The Stability ◽  
And Storage

ABSTRACT Sorption isotherms are of great importance in post-harvest procedures, especially for predicting drying and storage, which help to establish the final moisture content of the product under certain environmental condition. Hysteresis is a phenomenon that occurs due to the difference between adsorption and desorption curves, which aids the evaluation of chemical and microbiological deteriorations, indicating the stability of stored products. Moisture sorption isotherms of castor beans were determined and hysteresis was analyzed. Static gravimetric technique at different temperatures (25, 35, 45 and 55 ± 1 °C) was used. Saturated salt solutions in the range of 37-87% ± 2% were utilized to create the required controlled relative humidity environment. Equilibrium moisture content data were correlated by different mathematical models and the Modified Halsey model presented good adjustment for the data, according to statistical procedures. Hysteresis between adsorption and desorption isotherms is present over the range of 0.2-0.9 of water activity, regardless of the temperature. This phenomenon decreases with temperature increase.

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.

scholarly journals Modelling the moisture sorption isotherms of Roselle (Hibiscus sabdariffa L.) in the temperature range of 5–35 °C

2013 ◽  
Vol 61 (6) ◽  
pp. 1769-1777 ◽  
Author(s):  
Jitka Langová ◽  
Donludee Jaisut ◽  
Ratiya Thuwapanichayanan ◽  
Charotorn Phowong ◽  
Jiří Štencl ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Sorption ◽  
Structural Changes ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Ambient Air ◽  
Point Of View ◽  
Hibiscus Sabdariffa ◽  
Adsorption And Desorption ◽  
Moisture Sorption Isotherms

Water sorption tests of Roselle (Hibiscus sabdariffa L.) carried out under laboratory conditions are presented together with mathematical analyses of the moisture sorption isotherms (MSI’s). Moisture equilibrium data for adsorption and desorption of water from Roselle powder were investigated at near ambient air temperatures in the range of 5 and 35 °C and water activity (Aw) ranging from 0.11 to 0.97. The manometric method has been used for water sorption tests. Models for MSI’s are exponential equations. Coefficients of determination are 0.998 and 0.996 (for adsorption and desorption at 5 °C, respectively), 0.998 and 0.999 (for adsorption and desorption at 20 °C, respectively), and 0.998 and 0.999 (for adsorption and desorption at 35 °C, respectively). The equilibrium moisture content (EMC) of Roselle samples increased with an increase of Aw at a constant temperature both for adsorption and desorption. Adsorption curve equates to desorption curve at higher temperatures of tests carried out. Critical values of EMC of samples tested corresponding to the Aw equal to 0.6 were between 13.401% moisture content wet basis (MC w.b.) and 15.934% MC (w.b.) for moisture adsorption and desorption, respectively. These values are useful for storing conditions optimisation from point of view microorganisms grow and structural changes analyses. Crystal structure changes were observed during adsorption and desorption in the microscope, too. It was found out glass transition in dependence on the water content of samples tested.

scholarly journals Water sorption properties of Dutch type semi-hard cheese edge in the range of common storing temperatures

2011 ◽  
Vol 59 (5) ◽  
pp. 203-208 ◽  
Author(s):  
Maria Carolina Soares Pereira ◽  
Jiří Štencl ◽  
Bohumíra Janštová ◽  
Václav Vlášek
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Pure Water ◽  
Free Water ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Water Evaporation ◽  
Adsorption And Desorption ◽  
Moisture Sorption Isotherms ◽  
Hard Cheese

Moisture sorption isotherms of Dutch type semi-hard cheese edge in the temperature range of 10–25 ºC and water activity (Aw) from 0.11 to 0.98 were determined using manometric method. The sorption curves had a sigmoid shape. The equilibrium moisture content (EMC) of cheese samples increased with an increase in Aw at a constant temperature both for water adsorption and desorption. An increase in temperature caused an increase in Aw for the same moisture content (MC) and, if Aw was kept constant, an increase in temperature caused a decrease in the amount of absorbed water. Critical values of equilibrium moisture content, corresponding to the Aw = 0.6, were between 11 % MC (w.b.) and 17 % MC (w.b.) both for moisture adsorption and desorption. Values of sorption heat were calculated from moisture sorption isotherms by applying the Clausius-Clapeyron equation. Values of the heat of desorption are higher than those of adsorption and the difference increases with the MC decrease. Heat of sorption decreased from 48.5 kJ/mol (~5.5 % MC w.b.) to the values approaching the heat of vaporization of pure water, free MC. The critical value for free water evaporation is about w = 27 % (w.b.) for the range of temperature 10–25 ºC.

scholarly journals Moisture sorption isotherms of whole milk powder in the temperature range of 5–35 °C and critical values of water activity prediction

2014 ◽  
Vol 83 (10) ◽  
pp. S35-S40 ◽  
Author(s):  
Jitka Langová ◽  
Jiří Štencl
Keyword(s):  
Water Activity ◽  
Milk Powder ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Critical Values ◽  
Adsorption And Desorption ◽  
Temperature Range ◽  
Whole Milk ◽  
Moisture Sorption Isotherms ◽  
Whole Milk Powder

The study presents results of water sorption tests of whole milk powder in the temperature range of 5–35 °C and water activity (aw) from 0.11 to 0.97. The experimental procedure used was the manometric static method. Four sorption models recommended in literature sources (Chung-Pfost, Halsey, Henderson, Oswin) were analysed and evaluated with the aim of aw prediction. The modified Oswin’s equation was the best model for moisture adsorption and desorption of the whole milk powder. Critical values of the equilibrium moisture content (EMC) from the viewpoint of microorganism growth corresponding to the aw = 0.6 were calculated for the temperature range tested. The critical EMC was 7.82% and 8.51% wet basis (w.b.), for water adsorption and desorption, respectively, at the temperature of 20 ºC. Sorption capacity of samples tested decreased as temperature increased, and vice versa. The differences between the EMC values at a constant aw were small in the temperature range measured, and rehydration of the dried material resulted in hysteresis but this effect was non-significant.

scholarly journals Moisture sorption isotherms and heat of sorption of Algerian bay leaves (Laurus nobilis)

2015 ◽  
Vol 17 (4) ◽  
pp. 759-772 ◽  
Author(s):  
N Ouafi ◽  
H Moghrani ◽  
N Benaouada ◽  
N Yassaa ◽  
R Maachi ◽  
...  
Keyword(s):  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Laurus Nobilis ◽  
Heat Of Sorption ◽  
Moisture Sorption Isotherms
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