scholarly journals Modeling sorption isotherms and isosteric heat of sorption of roasted coffee beans

2018 ◽  
Author(s):  
Gentil Andres Collazos-Escobar ◽  
Nelson Gutiérrez-Guzmán ◽  
Henry Alexander Vaquiro-Herrera ◽  
Erika Tatiana Cortes-Macias
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Dew Point ◽  
Roasted Coffee ◽  
Sorption Data ◽  
Heat Of Sorption ◽  
Coffee Beans ◽  
Roasted Coffee Beans

The aim of this work was determine the sorption isotherms in roasted beans of specialty coffee at temperatures of 25, 30 and 40 °C and water activities between 0.1 and 0.8 using the dynamic dew point method. The experimental sorption data were modeled using 12 different equations to represent the dependence of equilibrium moisture content with aw and temperature. The net isosteric heat of sorption was determined from the experimental sorption data using the Clausius-Clapeyron equation. The Weibull model satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in roasted coffee beans (R2adj =0.902 and RMSE = 0.00550 kg·kg-1d.b.). The net isosteric heat of sorption increase with increased moisture content. Keywords: water activity; sorption properties; equilibrium moisture content; hygroscopicity

scholarly journals MODELING DYNAMIC ADSORPTION ISOTHERMS AND THERMODYNAMIC PROPERTIES OF SPECIALTY GROUND ROASTED-COFFEE (Coffee Arabica L.)

2019 ◽  
Vol 14 (1) ◽  
pp. 93 ◽  
Author(s):  
Gentil Andres Collazos-Escobar ◽  
Nelson Gutiérrez-Guzman ◽  
Henry A. Vaquiro Herrera
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Adsorption Isotherms ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Roasted Coffee ◽  
Sorption Data ◽  
Specialty Coffee ◽  
Sensorial Attributes

Specialty coffee is highly differentiated product because of  its sensorial attributes: aroma, body and brand reputation. In specialized markets, these products are highly valued, and sometimes up to six times their commercial value is paid. Thus, it is essential to preserve their freshness. Sorption isotherms are necessary for determining and studying water sorption changes in specialty coffee during storage. This study aimed to determine the adsorption isotherms of specialty ground roasted-coffee at temperatures of 25 °C, 30 °C and 40 °C and water activities between 0.1 and 0.8 using the dynamic dewpoint method (DDI). The experiment sorption data were modeled using 12 different equations with non-linear regression to represent the dependence of the equilibrium moisture content with both water activity and temperature. In addition, the thermodynamic properties were determined with the experiment adsorption data. The results showed that type III isotherms were obtained according to the Brunauer classification, and the Weibull equation satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in the specialty ground roasted-coffee. The results of thermodynamic analysis showed that the net isosteric heat of adsorption and Gibbs free energy decreased as the equilibrium moisture content increased, indicating the amount of energy released, a strong bond energy between water molecules in the product components and spontaneity in the adsorption process. The entropy of the adsorption increased with the moisture content, leading to product stability conditions during storage. The results were similar to those reported for the roasted and ground coffee of others cultivars.

Moisture Sorption Isotherms, Isosteric Heat of Sorption and Glass Transition Temperature of Murtilla (Ugni molinae T.) Berry

2014 ◽  
Vol 10 (4) ◽  
pp. 583-594 ◽  
Author(s):  
Kong S. Ah-Hen ◽  
Roberto Lemus-Mondaca ◽  
Karen A. Mathias-Rettig ◽  
Antonio Vega-Gálvez ◽  
Jessica López
Keyword(s):  
Experimental Data ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Sorption Data ◽  
Heat Of Sorption ◽  
Ugni Molinae

Abstract Adsorption and desorption isotherms of fresh and dried murtilla (Ugni molinae Turcz) berries were determined at 20, 40 and 60°C using a gravimetric technique. The experimental data obtained were fitted to eight models, namely GAB, BET, Henderson, Caurie, Smith, Oswin, Halsey and Iglesias–Chirife. A non-linear least square regression analysis was used to evaluate the models. The GAB model best fitted the experimental data. Isosteric heat of sorption was determined from the equilibrium sorption data using the Clausius–Clapeyron equation and was found to decrease exponentially with increasing moisture content. The enthalpy–entropy compensation theory applied to the sorption isotherms indicated an enthalpy controlled sorption process. Glass transition temperature of murtilla was determined by differential scanning calorimetry and modelled as a function of moisture content by the Gordon–Taylor equation and as function of water activity by Roos and Khalloufi models, which proved to be excellent tools for predicting glass transition of murtilla.

Sorption Isotherms and Isosteric Heat of Peanut Pods, Kernels and Hulls

2007 ◽  
Vol 13 (3) ◽  
pp. 231-238 ◽  
Author(s):  
P.C. Corrêa ◽  
A.L.D. Goneli ◽  
C. Jaren ◽  
D.M. Ribeiro ◽  
O. Resende
Keyword(s):  
Experimental Data ◽  
Relative Humidity ◽  
Moisture Content ◽  
Mathematical Models ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Statistical Parameters ◽  
Peanut Hulls ◽  
Pass Through

This study was carried out to evaluate the sorption isotherms of peanut pods, kernels and hulls for several temperature and humidity conditions and to fit different mathematical models to the experimental data, selecting the one best fitting the phenomenon. The dynamic method was applied to obtain the hygroscopic equilibrium moisture content. The environmental conditions were provided by means of an atmospheric conditioning unit, in which removable perforated trays were placed to allow air to pass through peanut mass, each one containing 50 g of the product. The mathematical models frequently used for the representation of hygroscopicity of agricultural products were fit to the experimental data. Based on those results, it was concluded that peanut pods, kernels and hulls presented differentiated hygroscopicity. The equilibrium moisture content for peanut pods, kernels and hulls increased with an increase in the relative humidity at any particular temperature and decreased with increase in temperature at constant relative humidity. At a constant water activity, peanut hulls samples had higher equilibrium moisture content than the pods and kernels samples. Based on statistical parameters, the modified Henderson and Chung-Pfost models were found to adequately describe the sorption characteristics of peanut pods, kernels and hulls. Isosteric heat of desorption were evaluated by applying the Clausius—Clapeyron equation to experimental isotherms and decreased with increasing moisture content. The peanut hulls had higher isosteric heat of sorption than that peanut pods and kernels.

Adsorption Isotherms for Red Onion Slices Using Empirical and Neural Network Models

2011 ◽  
Vol 7 (6) ◽  
Author(s):  
Hamid Reza Gazor ◽  
Afshin Eyvani
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Multilayer Perceptron ◽  
Sorption Isotherms ◽  
Network Models ◽  
Isosteric Heat ◽  
Neural Network Models ◽  
Isosteric Heat Of Adsorption

Moisture sorption isotherms of red onion slices were determined at 30, 40, 50, and 60°C using the standard gravimetric static method over a range of relative humidity from 0.11 to 0.83. The experimental sorption curves were fitted by seven empirical equations: modified Henderson, modified Chung–Pfost, modified Halsey, modified Oswin, modified Smith, modified BET, and GAB. Also three types of Artificial neural network models: linear, multilayer perceptron, and radial basis function were tested and developed to predict the equilibrium moisture content of onion slices and the selected models were trained by using related algorithms. The modified Oswin model was found acceptable for predicting adsorption moisture isotherms and fitting to the experimental data, based on the coefficient of determination (R2= 0.991), mean relative percent error (MRE=15.019), and standard error of estimation (SEE=1.371). Besides, multilayer perceptron model with four layers (2: 17: 14: 1) was selected as the best artificial neural network for estimation of onion slices’ equilibrium moisture content by considering R2= 0.993 and good performance. The net isosteric heat of adsorption of moisture was determined by applying the Clausius–Clapeyron equation to the sorption isotherms at different temperatures. The net isosteric heat of adsorption of red onion slices varied between 1.46 and 4.96 kJ/mol at moisture content varying between 2% and 52% (d.b.).

Moisture Sorption Characteristics of Dakuwa (Nigerian Cereal/Groundnut Snack)

2013 ◽  
Vol 9 (4) ◽  
pp. 499-504 ◽  
Author(s):  
Ocheme Boniface Ocheme ◽  
Chukwuma Charles Ariahu ◽  
Emmanuel Kongo Ingbian
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Goodness Of Fit ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Sorption Data ◽  
Moisture Contents ◽  
Monolayer Moisture ◽  
Increasing Temperature ◽  
Sorption Characteristics

AbstractThe moisture sorption characteristics of dakuwa at 10, 20, 30 and 400°C were studied. The experimental sorption data obtained were applied to BET, GAB, Oswin and Henderson equations to test fitness of the equations to moisture sorption of dakuwa. The sorption isotherms of dakuwa were type III isotherms (J shaped), and the equilibrium moisture content increased with increasing water activity but decreased with increasing temperature. The BET and GAB monolayer moisture contents all decreased with increasing temperature. For adsorption, the BET monolayer was higher (3.163–4.158 g/100 g solid) than that of GAB (2.931–3.728 g/100 g solid), but for desorption, the GAB monolayer (4.792–7.741 g/100 g solid) was higher than that of BET (3.962–4.480 g/100 g solid). Evaluation of goodness of fit of models revealed that moisture sorption of dakuwa was best modelled by GAB equation.

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 Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits

2017 ◽  
Vol 21 (4) ◽  
pp. 285-289
Author(s):  
Daniel E. C. de Oliveira ◽  
Osvaldo Resende ◽  
Lílian M. Costa ◽  
Glicélia P. Silva ◽  
Juliana de F. Sales
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Dynamic Method ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Coefficient Of Determination ◽  
Chi Square ◽  
Mean Error ◽  
Technological Information ◽  
Desorption Isotherms

ABSTRACT ‘Sucupira-branca’ (Pterodon emarginatus Vogel) is a tree from ‘Cerrado’ and stands out mainly for its pharmacological properties; however, there are no technological information about its post-harvest operations. Thus, the aim of this study was to determine the sorption isotherms of ‘sucupira-branca’ fruits for different air conditions and obtain the values of desorption isosteric heat, depending on the equilibrium moisture content of the product. The equilibrium moisture content of ‘sucupira-branca’ fruits was determined by dynamic method for temperatures of 25, 30, 35 and 40 °C and water activities for each temperature between 0.270 and 0.775. The models Chung-Pfost, Copace, Modified Halsey, Oswin Modified and Sigma Copace obtained high coefficient of determination (R2) and low chi-square (χ2), relative mean error (P) and estimated mean error (SE), and the Copace model was selected to represent the desorption isotherms. The isosteric heat increases with the reduction of equilibrium moisture content and required more energy to remove water from the ‘sucupira-branca’ fruit.

scholarly journals Determination of desorption isotherms, latent heat and isosteric heat of pequi diaspore

2016 ◽  
Vol 20 (5) ◽  
pp. 493-498 ◽  
Author(s):  
Kelly A. de Sousa ◽  
Osvaldo Resende ◽  
Bruno de S. Carvalho
Keyword(s):  
Moisture Content ◽  
Latent Heat ◽  
Equilibrium Moisture Content ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Static Method ◽  
The One ◽  
Content Range ◽  
Water Sorption Isotherms

ABSTRACT The objective was to determine water sorption isotherms of diaspores of pequi fruits in order to obtain information on the amount of water that this product desorbs at the temperatures of 10, 20, 30 and 40 °C and water activities from 0.20 to 0.89, adjusting different mathematical models to experimental data, and to determine its latent heat and isosteric heat. The equilibrium moisture content was obtained through the indirect static method, using the device Hygropalm Model Aw 1. The Modified Henderson model was the one that best fitted the data and was selected to predict the equilibrium moisture content of pequi diaspore. It was observed that the higher the temperature for the same equilibrium moisture content (% d.b.), the higher the water activity values. As temperature values increased, there was a reduction in the vaporization latent heat of the product. Isosteric heat values of diaspores of pequi fruits in the moisture content range of 4.02 to 16.63 (% d.b.) varied from 2,776.49 to 2,558.39 kJ kg-1.

scholarly journals EVALUASI MUTU KOPI ROBUSTA DI KECAMATAN KARE KABUPATEN MADIUN JAWA TIMUR

Pro Food ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 729
Author(s):  
Choiroel Anam ◽  
Eny Muzayana ◽  
Rohmat Priya Atmaja ◽  
Didik Purnomo
Keyword(s):  
Moisture Content ◽  
Microbiological Quality ◽  
Coffee Bean ◽  
Roasted Coffee ◽  
Physical Quality ◽  
Caffeine Content ◽  
Physical Chemical ◽  
Coffee Beans ◽  
Roasted Coffee Beans

ABSTRACT   Coffee is a leading commodity in Madiun Regency, East Java, the area of coffee plantations in 2018  is 1,432 Ha with an average productivity of 769.63 kg / ha /year.  This study aims to provide information on the physical, chemical, and microbiological quality characteristics of rice coffee, roasted coffee beans and evaluate the primary processing procedures for Mugi Lestari Farmer Group's coffee in Kare Village, Kare District, Madiun Regency. Evaluation of the quality of coffee rice is based on general and specific quality equirements according to SNI 01-2907: 2008. Organoleptic and chemical analysis of rice coffee and roasted coffee beans was carried out to see the state (smell, taste), moisture content, ash content, ash alkalinity, caffeine content, sugar content (reducing), insoluble solids, metal contaminants (Pb and Cu). Assessment of the physical quality of coffee beans shows that the robusta rice coffee produced at Poktan Mugi Lestari has quality according to SNI 01-2907-2008, especially for the parameters of the presence of insects, moisture content, impurities, and no found odor/mold.  Physical quality of roasted coffee beans from Poktan Mugi Lestari when compared to SNI standards has a normal condition, both in terms of smell, taste, and appearance. Chemical parameters of roasted coffee bean samples are also in accordance with the general requirements for roasted coffee (SNI 01-2983-1992). The number of bacteria and molds is less than the maximum limit set. Assessment of physical, chemical, and microbiological quality of packaged coffee powder has a value in accordance with the SNI quality requirements, both for caffeine content, the amount of mold, and bacteria (ALT value), and water content. The primary coffee processing process at Poktan Mugi Lestari has been able to produce rice coffee in accordance with SNI requirements.   Keywords: coffee, robusta, quality, kare madiun   ABSTRAK               Kopi merupakan komoditas unggulan di Kabupaten madiun Jawa Timur, Luas areal perkebunan kopi tahun 2018 di Kabupaten Madiun  1.432 Ha dengan produktivitas rata rata 769,63 kg/ha/tahun. Penelitian ini bertujuan memberikan informasi karakteristik mutu fisik, kimiawi, dan mikrobiologis dari kopi beras, kopi biji sangrai dan mengevaluasi prosedur pengolahan primer kopi Kelompok Tani Mugi Lestari di desa Kare, Kecamatan Kare, Kab Madiun, agar dihasilkan produk dengan mutu yang baik. Evaluasi mutu kopi beras didasarkan pada syarat mutu umum dan khusus sesuai SNI 01-2907:2008. Analisa organoleptik dan kimiawi kopi beras dan kopi biji sangrai dilakukan untuk melihat keadaan (bau, rasa), kadar air, kadar abu, kealkalian abu, kadar kafein, kadar gula (pereduksi), padatan tak larut dalam air, cemaran logam (Pb dan Cu). Penilaian mutu fisik biji kopi diketahui bahwa kopi beras robusta yang dihasilkan di Poktan Mugi Lestari memiliki mutu sesuai dengan SNI 01-2907-2008, khususnya untuk parameter keberadaan serangga, nilai kadar air, pengotor, dan tidak ditemukannya bau busuk/kapang. Keadaan mutu fisik biji kopi sangrai dari Poktan Mugi Lestari jika dibandingan dengan SNI 01-2983-1992 memiliki keadaan yang normal, baik dalam hal bau, rasa, dan penampakan. Parameter kimiawi biji kopi sangrai dalam penelitian juga sesuai dengan syarat umum kopi sangrai (SNI 01-2983-1992). Jumlah bakteri dan kapang kurang dari batas maksimum yang ditetapkan. Penilaian mutu fisik, kimiawi, dan mikrobiologis bubuk kopi yang dikemas memiliki nilai sesuai dengan persyaratan mutu SNI, baik untuk kadar kafein, jumlah kapang, dan bakteri (nilai ALT), dan kadar air. Proses pengolahan primer kopi di Poktan Mugi Lestari sudah mampu menghasilkan kopi beras yang sesuai dengan persyaratan SNI.     Kata kunci: Kopi, Robusta, Mutu, Kare Madiun

Determination of Moisture Sorption Isotherms of Jasmine Rice Crackers Using BET and GAB Models

2006 ◽  
Vol 12 (6) ◽  
pp. 459-465 ◽  
Author(s):  
U. Siripatrawan ◽  
P. Jantawat
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Sorption Data ◽  
Heat Of Sorption ◽  
Moisture Sorption Isotherms ◽  
Jasmine Rice ◽  
Gab Model ◽  
Best Fit

Moisture sorption isotherms of Thai Jasmine rice crackers were determined at 30, 45 and 60°C over a water activity range of 0.10 to 0.95 using a static gravimetric technique. Moisture sorption isotherms of rice crackers exhibited the sigmoid (Type II) shape. The moisture content of rice crackers decreased as temperature increased at a given water activity of the storage environment. The Brunauer, Emmett and Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models were applied to fit the experimental data. The isosteric heat of sorption at different moisture levels was also determined using the Clausius–Clapeyron thermodynamic equation. A nonlinear regression analysis method was determined to evaluate the parameters of sorption equations. The criteria used to evaluate the goodness of fit of each model were the mean relative percentage deviation modulus (E) and the percentage root mean square error (RMSE). The more extended range of application of the GAB equation over the BET equation was evident. The GAB model gave the best fit to the experimental sorption data for a wide range of water activity (0.10–0.95) while the BET model gave the best fit for a water activity range of less than 0.60. The GAB model is considered suitable to predict the moisture sorption isotherm of rice crackers since it gave low E and RMSE values. The heat of sorption values of rice crackers were found to be large at low moisture content and decreased with an increase in food moisture content.

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