scholarly journals Desorption isotherms and isosteric heat of niger grains (Guizotia abyssinica (L. f.) Cass.)

2018 ◽  
Vol 12 (2) ◽  
pp. 124 ◽  
Author(s):  
Valdiney Cambuy Siqueira ◽  
Fernanda Pimentel Da Silva ◽  
Wellytton Darci Quequeto ◽  
Rodrigo Aparecido Jordan ◽  
Rafael Araujo Leite ◽  
...  
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Mathematical Models ◽  
Water Activity ◽  
Seed Oil ◽  
Oil Quality ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Seed Moisture Content ◽  
Desorption Isotherms

Niger seed oil has excellent quality and quantity (30-50%) and is rich in polyunsaturated fatty acids, mainly linoleic acid (about 70%). Thus, control of environmental temperature and relative humidity, and of seed moisture content is essential to maintain seed oil quality during storage. Thus, the objective of this study was to determine the desorption isotherms of niger seeds under different temperature and water activity conditions, to test the experimental data with different mathematical models, and discover which best represents the phenomenon, as well as calculate the isosteric heat value for the product. Hygroscopicity was determined by the static gravimetric method, at temperatures of 30, 35 and 40 ºC, and water activity between 0.07 and 0.79 (decimal). For the experimental data, mathematical models commonly used to test hygroscopicity in agricultural products were evaluated. From the results obtained, it was concluded that: water activity increases as moisture content rises; based on the statistical parameters, the models of Chung and Pfost, modified Henderson, Oswin, Sabbah, Sigma Copace, Halsey, Smith and Copace appropriatrely represented the desorption phenomenon of niger seeds; total isosteric desorption heat increased with reduction of moisture content, with values varying from 2539.62 to 3081.48 kJ kg-1, within the range of equilibrium moisture content of 2.4 to 12.2 (% dry basis).

scholarly journals Thermodynamic properties of water sorption of jackfruit (Artocarpus heterophyllus Lam.) as a function of moisture content

2013 ◽  
Vol 33 (1) ◽  
pp. 199-208 ◽  
Author(s):  
Ana Paula Prette ◽  
Francisco de Assis Cardoso Almeida ◽  
Harvey Alexander Villa-vélez ◽  
Javier Telis-Romero
Keyword(s):  
Thermodynamic Properties ◽  
Moisture Content ◽  
Water Activity ◽  
Water Sorption ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Effect Of Temperature ◽  
Artocarpus Heterophyllus ◽  
Biological Damage ◽  
Desorption Isotherms

The Jackfruit tree is one of the most significant trees in tropical home gardens and perhaps the most widespread and useful tree in the important genus Artocarpus. The fruit is susceptible to mechanical and biological damage in the mature state, and some people find the aroma of the fruit objectionable, particularly in confined spaces. The dehydration process could be an alternative for the exploitation of this product, and the relationship between moisture content and water activity provides useful information for its processing and storage. The aim of this study was to determine the thermodynamic properties of the water sorption of jackfruit (Artocarpus heterophyllus Lam.) as a function of moisture content. Desorption isotherms of the different parts of the jackfruit (pulp, peduncle, mesocarp, peel, and seed) were determined at four different temperatures (313.15, 323.15, 333.15, and 343.15 K) in a water activity range of 0.02-0.753 using the static gravimetric method. Theoretical and empirical models were used to model the desorption isotherms. An analytical solution of the Clausius-Clapeyron equation was proposed to calculate the isosteric heat of sorption, the differential entropy, and Gibbs' free energy using the Guggenhein-Anderson-de Boer and Oswin models considering the effect of temperature on the hygroscopic equilibrium.

scholarly journals Post-harvest of parsley leaves (Petroselinum crispum): Mathematical modelling of drying and sorption processes

2018 ◽  
Vol 22 (2) ◽  
pp. 131-136 ◽  
Author(s):  
Luiz C. Corrêa Filho ◽  
Ana P. Martinazzo ◽  
Carlos E. de S. Teodoro ◽  
Ednilton T. de Andrade
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Mathematical Modelling ◽  
Mathematical Models ◽  
Water Loss ◽  
Isosteric Heat ◽  
Petroselinum Crispum ◽  
High Consumption ◽  
Desorption Isotherms ◽  
Drying Curves

ABSTRACT Parsley is a species of wide production and trade in Brazil due to its high consumption as a condiment, fresh or dried. In the development of equipment used for drying, it is important to simulate and obtain theoretical information about the behavior of water loss for each product. Given the increasing use and potential commercialization of condimental plants, the objective of this work was to determine the isosteric heat of parsley leaves and fit mathematical models to the experimental data obtained in drying and desorption processes. The modified GAB and Midilli models were the most appropriate to describe the desorption isotherms and drying curves, respectively, for the studied temperatures. The isosteric heat varied from 3394.6 to 2830.0 kJ kg-1 for the equilibrium moisture content in the range from 0.0154 to 3.7232 (d.b.).

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.

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 Moisture Adsorption and Thermodynamic Properties of California Grown Almonds (Varieties: Nonpareil and Monterey)

2012 ◽  
Vol 1 (1) ◽  
Author(s):  
Li Zuo Taitano ◽  
R.P. Singh
Keyword(s):  
Diffusion Coefficient ◽  
Thermodynamic Properties ◽  
Moisture Content ◽  
Water Activity ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Moisture Adsorption ◽  
Constant Weight ◽  
Differential Enthalpy ◽  
Monolayer Moisture

Moisture adsorption characteristics of California grown almonds (Nonpareil: pasteurized and unpasteurized almonds; Monterey: pasteurized, unpasteurized and blanched almonds) were obtained using the gravimetric method over a range of water activities from 0.11 to 0.98 at 7-50ºC. The weights of almonds were measured until samples reached a constant weight. The relationship between equilibrium moisture content and water activity was established using the Guggenheim-Anderson-de Boer model. The diffusion coefficient of water in almond kernels was calculated based on Ficks second law. The monolayer moisture value of almonds ranged from 0.020 to 0.035 kg H2O kg-1 solids. The diffusion coefficient increased with temperature at a constant water activity, and decreased with water activity at a constant temperature. The thermodynamic properties (net isosteric heat, differential enthalpy and entropy) were also determined. The net isosteric heat of adsorption decreased with the increasing moisture content, and the plot of differential enthalpy versus entropy satisfied the enthalpy-entropy compensation theory. The adsorption process of almond samples was enthalpy driven over the range of studied moisture contents.

scholarly journals Desorption isotherms and isosteric heat of araticum (Annona crassiflora Mart.) seeds

2020 ◽  
Vol 24 (9) ◽  
pp. 630-636
Author(s):  
Weder N. Ferreira Junior ◽  
Osvaldo Resende ◽  
Kelly A. de Sousa ◽  
Melícia I. A. Gavazza ◽  
Juliana de F. Sales ◽  
...  
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Nonlinear Regression ◽  
Regression Models ◽  
Information Criterion ◽  
Isosteric Heat ◽  
Nonlinear Regression Models ◽  
Desorption Isotherms ◽  
Annona Crassiflora ◽  
Content Range

ABSTRACT The objective of this study was to determine the desorption isotherms and isosteric heat of Annona crassiflora Mart. seeds, using Akaike information criterion (AIC) and Schwarz’s Bayesian information criterion (BIC) to assist in the choice of the nonlinear regression model. The desorption isotherms were determined by indirect static method and water activity was obtained using the instrument HygroPalm; the product was put in the device in B.O.D. chamber set at 10, 20, 30 and 40 °C. Several nonlinear regression models were fitted to the experimental data by the Gauss-Newton method. The desorption isotherms of Annona crassiflora Mart. seeds can be represented by the models of Chung-Pfost, Copace, Modified GAB, Modified Henderson, Modified Oswin, Sabbah and Sigma Copace. However, the Sigma Copace model showed better fit to the experimental data, with lower AIC and BIC values, being chosen to represent the desorption isotherms of Annona crassiflora Mart seeds. Isosteric heat increased with decreasing moisture content, requiring a greater amount of energy to remove water from seeds, with values ranging from 2541.64 to 2481.56 kJ kg-1, for the moisture content range from 5.69 to 14.93% on a dry basis.

scholarly journals Desorption isotherms and isosteric heat of 'cajuzinho-do-cerrado' achenes

2016 ◽  
Vol 20 (5) ◽  
pp. 481-486 ◽  
Author(s):  
Karine F. Barbosa ◽  
Juliana de F. Sales ◽  
Osvaldo Resende ◽  
Daniel E. C. de Oliveira ◽  
Jacson Zuchi ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
National Park ◽  
Linear Regression Analysis ◽  
Isosteric Heat ◽  
Static Method ◽  
Different Temperatures ◽  
Desorption Isotherms ◽  
The One ◽  
Content Range

ABSTRACT The objective of this study was to determine the desorption isotherms of 'cajuzinho-do-cerrado' achenes (Anacardium humile St. Hil.) in various conditions of temperature and water activity, as well as to select the one that best represents the phenomenon and to determine the isosteric heat of desorption. The fruits were collected at the Emas National Park, in the municipality of Mineiros-GO, Brazil, pulped and then subjected to drying in silica gel at temperature of 25 ± 2 °C until the moisture contents of 17.6, 13.6, 11.1, 8.7 and 5.3 (d.b.%). After drying, the desorption isotherms were determined by the indirect static method. The water activity (Aw) was determined at different temperatures, and the achenes were placed in a B.O.D. chamber, regulated at 10, 20, 30 and 40 °C. Data of hygroscopic equilibrium moisture content were fitted to different mathematical models through non-linear regression analysis, using the Gauss-Newton method. The Copace model was the one that best represented the hygroscopicity of 'cajuzinho-do-cerrado' achenes, while the integral isosteric heat of desorption of 'cajuzinho-do-cerrado' achenes for the moisture content range of 4.51 to 13.40 (% d.b.) varied from 2,734.82 to 2,548.49 kJ kg-1.

Influence of oil content on the equilibrium moisture content of evening primrose ( Oenothera SPP.) seeds

2007 ◽  
Vol 55 (4) ◽  
pp. 485-489 ◽  
Author(s):  
A. Fieldsend
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Oil Content ◽  
Seed Oil ◽  
Oil Quality ◽  
Seed Oil Content ◽  
Seed Moisture Content ◽  
Evening Primrose ◽  
Seed Moisture ◽  
The Relationship

Seed moisture content is a well-recognised index of safe storage. However, when in equilibrium with the storage environment it is merely an indicator of the relative humidity of the air, which is the primary regulator of the growth of moulds and insects. The relationship is influenced by the profile of the seed components. During the 1990s, significant increases in the seed oil content of evening primrose were achieved through plant breeding. This paper shows that the equilibrium moisture content of evening primrose seeds declines significantly with increasing oil content. Hence, the moisture isotherm is altered and newer cultivars must be stored at slightly lower seed moisture contents to ensure that seed and oil quality are maintained.

scholarly journals Moisture Adsorption and Thermodynamic Properties of California Grown Almonds (Varieties: Nonpareil and Monterey)

2012 ◽  
Vol 1 (1) ◽  
Author(s):  
Li Zuo Taitano ◽  
R.P. Singh
Keyword(s):  
Diffusion Coefficient ◽  
Thermodynamic Properties ◽  
Moisture Content ◽  
Water Activity ◽  
Gravimetric Method ◽  
Isosteric Heat ◽  
Moisture Adsorption ◽  
Constant Weight ◽  
Differential Enthalpy ◽  
Monolayer Moisture

Moisture adsorption characteristics of California grown almonds (Nonpareil: pasteurized and unpasteurized almonds; Monterey: pasteurized, unpasteurized and blanched almonds) were obtained using the gravimetric method over a range of water activities from 0.11 to 0.98 at 7-50ºC. The weights of almonds were measured until samples reached a constant weight. The relationship between equilibrium moisture content and water activity was established using the Guggenheim-Anderson-de Boer model. The diffusion coefficient of water in almond kernels was calculated based on Ficks second law. The monolayer moisture value of almonds ranged from 0.020 to 0.035 kg H2O kg-1 solids. The diffusion coefficient increased with temperature at a constant water activity, and decreased with water activity at a constant temperature. The thermodynamic properties (net isosteric heat, differential enthalpy and entropy) were also determined. The net isosteric heat of adsorption decreased with the increasing moisture content, and the plot of differential enthalpy versus entropy satisfied the enthalpy-entropy compensation theory. The adsorption process of almond samples was enthalpy driven over the range of studied moisture contents.

scholarly journals Modelling Thermodynamic Properties of Banana Waste by Analytical Derivation of Desorption Isotherms

2012 ◽  
Vol 8 (1) ◽  
Author(s):  
Harvey A. Villa-Vélez ◽  
Henry A. Váquiro ◽  
José Bon ◽  
Javier Telis-Romero
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Isosteric Heat ◽  
Effect Of Temperature ◽  
Agricultural Product ◽  
Different Temperatures ◽  
Desorption Isotherms ◽  
Gab Model ◽  
Processing And Storage ◽  
The Relationship

Banana is an agricultural product of great economic importance for various developing countries. The relationship between moisture content and water activity provides useful information for the processing and storage of banana waste. The water activity and moisture content of three banana (Mussa spp. Haploid AAB cv. Nanica) waste items were analyzed to determine the desorption isotherms at six different temperatures (20, 30, 40, 50, 60 and 70°C). The desorption isotherms of the peel, pedicel and pulp of overripe bananas were determined in wide ranges of moisture content (0.001–6.360 kg kg-1 d.b.) and water activity (0.02–0.907). The theoretical GAB model was used for modelling the desorption isotherms. An analytical solution of the Clausius-Clapeyron equation was proposed to compute the isosteric heat of sorption, the differential entropy and Gibbs’ free energy by way of the GAB model when the effect of temperature on the hygroscopic equilibrium was considered.

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