scholarly journals Moisture sorption isotherms of raw and extruded wholemeal sorghum flours studied by the dynamic and salt slurry methods

2018 ◽  
Vol 21 (0) ◽  
Author(s):  
Melicia Cintia Galdeano ◽  
Renata Valeriano Tonon ◽  
Carlos Wanderlei Piler de Carvalho ◽  
Neuri Santos Menezes ◽  
Regina Isabel Nogueira ◽  
...  
Keyword(s):  
Water Activity ◽  
Dynamic Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
High Water ◽  
Grain Sorghum ◽  
Equilibration Time ◽  
Whole Grain ◽  
Sorghum Flour ◽  
Slurry Method

Abstract The saturated salt slurry method has been a standard method for many years, but there are several drawbacks, including long equilibration times, extensive labour and mould growth at high water activity (aw) values. The validity of the dynamic method (automated sorption instrument) was investigated by comparing it with the equilibrium isotherms obtained using the saturated salt slurry method for two food materials (whole sorghum raw flour and whole grain sorghum extrudates), as well as their diffusion coefficients. The sorption isotherms ranged between 11.3% and 84.3%. The equilibration time for the highest water activity (0.843) was about 30 days using the saturated salts method, considerably longer than using the dynamic method (300 min). For raw sorghum flour, the dynamic method values were consistent with the data obtained using the traditional method, which can be confirmed by the similar curves and monolayer values obtained (0.038 and 0.040 g water / g solids for the salt slurry and dynamic methods, respectively). For the sorghum extrudates, the equilibrium moisture values were higher using the dynamic method, which could be related to the low diffusion coefficient of the material (order of 10 -10). The authors suggest the use of the dynamic method as a better alternative to the saturated salt method in order to determine the sorption isotherms of whole grain sorghum-based food materials.

scholarly journals Effect of temperature on moisture sorption phenomena in agricultural products

2005 ◽  
Vol 53 (4) ◽  
pp. 177-184 ◽  
Author(s):  
Jiří Štencl
Keyword(s):  
Water Activity ◽  
Dynamic Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Effect Of Temperature ◽  
Relative Air Humidity ◽  
Introductory Part ◽  
Moisture Sorption Isotherms ◽  
Model Equations ◽  
Dehydration Processes

The paper demonstrates importance of temperature influence on dehydration processes using drying model equations in introductory part and further presents results of water sorption tests of parsley leaves. Measurements were carried out under laboratory conditions in the temperature range of 10–40 °C and relative air humidity from 30 to 100%. Moisture sorption isotherms were tested using a gravimetric dynamic method with continuous recording of changes in sample weight. Five mathematical models available in the literature (Chung-Pfost, GAB, Halsey, Henderson, and Oswin) were statistical evaluated. The Henderson equation was found to be a good model both for moisture adsorption and desorption. Part of the sorption isotherms measured in parsley leaves show the type II BET classification shape. An increase in temperature causes an increase in water activity for the same moisture content and, if water activity is kept constant, an increase in temperature causes a decrease in the amount of absorbed water.

scholarly journals Comparative evaluation of whole grains flour chemical composition of grain sorghum (Sorghum bicolor) and chia (Salvia hispanica)

2020 ◽  
pp. 168-177
Author(s):  
S. Tretiakova ◽  
V. Voitovska ◽  
Y. Yevchuk ◽  
L. Kononenko
Keyword(s):  
Celiac Disease ◽  
Chemical Composition ◽  
Raw Materials ◽  
Chemical Constituents ◽  
Grain Sorghum ◽  
Gluten Free ◽  
Whole Grain ◽  
Free Products ◽  
Salvia Hispanica ◽  
Sorghum Flour

The article highlights a complex of studies and a comparative assessment of flour of various varieties and hybrids of chia and sorghum. It was found that, in terms of their chemical composition, these crops are advisable to use as raw materials for the production of gluten free products. To live a full life, people with celiac disease must constantly consume gluten-free foods. Rice, buckwheat, millet, corn are considered safe, and amaranth, quinoa, sago, Setaria italica, sorghum are also less common in Ukraine. To obtain high-quality gluten-free products, it is important to choose the right raw materials and their ratio in chemical composition. Therefore, it is advisable to study and compare the chemical composition of sorghum and chia flour. The aim of the research was to study and compare the chemical composition of whole grain sorghum flour versus chia for use in the food industry as a source of gluten-free nutrition. The experimental part of the work was carried out during 2017–2019 in the hybrids of grain sorghum of Ukrainian (Lan 59), French (Targga) and American (Prime) selection and Spanish sage (chia) (Salvia hispanica) varieties: Salba, Tzotzol, Iztac. Whole grain sorghum and chia flours were obtained from their grains and various chemical constituents were determined. Comparative analysis of the chemical composition of sorghum and chia flour allows us to note that, on average, the protein content in sorghum was in the range from 9.53 to 10.6 g, in chia varieties from 14.98 to 16.52 g, which is on average five, 8 g more. The data on the determination of fats show that in the hybrid of sorghum of Ukrainian selection, this indicator was 2.8 g, French 1.24 g, and American – 3.3 g, as for chia, this indicator is much higher and varies by varieties from 30, 12 to 30.71 g. Starch is the main component of flour and in sorghum; its mass fraction is more in the Prime hybrid 63.7 g, Lan 59 – 63.1 g and the smallest amount in Targga – 62.7 g. It has been determined that grain sorghum and chia flour has a high content of B vitamins, which act as coenzymes of a number of metabolic processes. In addition to the vitamins listed above, sorghum flour contains vitamins B9, B5, B6 as well. Chia varieties have high levels of micro- and microelements. Key words: flour, vitamins, microelements, proteins, fats, carbohydrates, celiac disease, sorghum, chia.

scholarly journals Moisture Sorption Behaviour and Mould Ecology of Trade Garri Sold in South Eastern Nigeria

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Tochukwu Samuel ◽  
J. Obeta Ugwuanyi
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Central Africa ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Fungal Species ◽  
Temperature Dependent ◽  
Sorption Behaviour ◽  
Moisture Sorption Isotherms ◽  
West And Central Africa

Garri is a creamy white or yellow starchy grit produced by roasting to gelatinization and dryness of peeled, washed, mashed, and fermented dewatered cassava roots. It is the most important product of cassava in West and Central Africa. Mean moisture content of yellow and white garri was 11.11% and 10.81% within 24 hrs of sampling from the market, increasing to 17.27% and 16.14%, respectively, following 3 months of storage at room temperature. The water activity of samples varied from initial 0.587 to 0.934 following storage. Moisture sorption isotherms, determined by static gravimetric techniques at 20° and 30°C, showed temperature dependent BET Sigmoidal type II behaviour typical of carbohydrate rich foods but modulated very slightly by the content of palm oil. Equilibrium moisture content decreased with increase in temperature at constant water activity. A total of 10 fungal species belonging to the generaMucor,Penicillium,Cephalosporium,Aspergillus,Scopulariopsis,Rhizopus, and Paecilomyceswere identified, with range increasing with water activity of samples.

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.

Moisture Sorption Isotherms and Net Isosteric Heats of Sorption of Green Soybean

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Zhao Yang ◽  
Enlong Zhu ◽  
Zongsheng Zhu
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Sorption Capacity ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Isosteric Heat ◽  
Model Parameters ◽  
Desorption Process ◽  
Moisture Sorption Isotherms

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.

scholarly journals Moisture Sorption Isotherms And Thermodynamic Properties Of Urtica Dioica Leaves

2016 ◽  
Vol 12 (24) ◽  
pp. 376 ◽  
Author(s):  
Abdelkader Lamharrar ◽  
Ali Idlimam ◽  
Mohammed Kouhila ◽  
Lamya Lahnine ◽  
Hind Mouhanni
Keyword(s):  
Water Activity ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Storage Conditions ◽  
Urtica Dioica ◽  
Endemic Plant ◽  
Clapeyron Equation ◽  
Moisture Sorption Isotherms ◽  
Different Temperatures

Urtica dioica is a Moroccon endemic plant of used for its virtues in traditional medicine. Thus, it is necessary to study the effect of preservation processes on the storage conditions of the plant. The static gravimetric method was used to determine sorption isotherms of Urtica dioica leaves at three temperatures (40, 50 and 60 °C) and in the range of water activity ( w a ) ranging from 0.0572 to 0.898. Six mathematical models were used to fit the experimental data. The Enderby and Peleg models were found to be the most suitable for describing the sorption curves. The optimal water activity for conservation of Urtica dioica leaves was determined. Isosteric heats of desorption and adsorption were calculated by applying the Clausius- Clapeyron equation to the sorption isotherms at different temperatures; it decreased with increasing moisture content. A linear relation exists between the enthalpy and entropy of the sorption reaction.

The prediction of moisture adsorption isotherm for sucrose powder in Côte d’Ivoire

2018 ◽  
Vol 6 (04) ◽  
Author(s):  
Yué Bi Yao Clément ◽  
Akmel Djédjro Clément ◽  
Tano Kablan
Keyword(s):  
Adsorption Isotherm ◽  
Moisture Content ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Least Square ◽  
Moisture Adsorption ◽  
Wide Range ◽  
Gab Model ◽  
And Storage

Moisture sorption isotherms play an essential role in preservation and storage of dehydrated food. To study the behavior of sucrose, it’s moisture adsorption isotherm was investigated using the static gravimetrique method at laboratory temperature (29 ±1°C) in a water activity range (aw) of 0.07-0.97. The results showed that the equilibrium moisture content of sucrose increase substantially above aw = 0.6. The moisture adsorption isotherm was sigmoid in shap, showing a type III BET isotherm. The data obtained were fitted to several models including two-parameter (BET, Hasley, Kuhn and Oswin), three parameter (GAB). A non-linear least square regression analysis was used to evaluate the models constants. The GAB model best fitted the experimental data in the wide range of water activity. The best fitted equation provide a sound basis for futur work on the drying and storage of sucrose. The accurate moisture content and the stability profile of sucrose were determined. The results of determination show that sucrose powder was stable below 7.7% RH at 29°C. The content of water adsorbed in the monomolecular layer was calculated (GAB Xm=0.950 g H2O/100 g solids; BET Xm= 1.072 g H2O/100 g solids).

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