Oswin Model Research Articles

Study of Water Desorption Isotherms from Cocoa Beans (Theobroma Cacao L.) of Cameroon

The aim of this work was the determination of desorption isotherms from cocoa beans at different temperatures (20°C, 30°C, 35°C, 40°C and 45°C), moisture ratio (10% and 90%). Gravimetric method and different temperatures were used to get the experimental moisture ratio at equilibrium. Experimental data were adjusted to mathematical isotherm models frequently used for the hygroscopic representation of agricultural products. Cocoa beans varied from 0 to 13% moisture ratio equilibrium. Obtained results showed that the moisture ratio at equilibrium decreases as temperature increases for the same relative humidity. Statistical parameters, modified the Oswin model, GAB, Iglesias Chirife Hasley and Chungs Pfost modified model better represented hygroscopic balance for cocoa beans than Henderson modified and Harkings Jura models. Desorption isotherm models are important for the determination of desorption energy and drying models. The desorption isotherms of cocoa beans were satisfactorily modeled by modified Oswin, GAB, Iglesias, Chirife, Halsey, and modified Chungs Pfost, which can be used as tools in the prediction and optimization of storage conditions in a wide range of water activities and temperatures.

Comparative Effect of Different Plasticizers on Barrier, Mechanical, Optical, and Sorption Properties of Hydroxypropyl Methylcellulose (HPMC)–Based Edible Film

Identifying ideal plasticizer is pivotal to develop a biopolymer-based edible films for food packaging. The effect of different plasticizers (glycerol, polyethylene glycol, sorbitol) on the mechanical, water vapor barrier, optical, and moisture sorption properties of hydroxypropyl methylcellulose (HPMC) -based flexible films was examined in this study. Mechanical properties and water vapor permeability (WVP) of films were determined using standard ASTM methods. Moisture sorption isotherm (MSI) for different HPMC films were obtained thermogravemitically and seven sorption models were fitted to experimental sorption data through nonlinear regression using curve fitting tool in MATLAB R2015b and goodness of fit of these models was compared based on Akaike information criterion (AIC). GAB model was used to determine the monolayer moisture content and heat of sorption of different films. Plasticizing efficacy of different plasticizers was significantly different for HPMC film in studied concentration range. Water vapor permeability (WVP) for native HPMC film was 0.451 g mm/kPa m2 h, which further increased to 0.972, 0.890, and 0.615 g mm/kPa m2 h when 25% (w/w of HPMC) glycerol, PEG, and sorbitol were added as plasticizers, respectively. GAB model showed an increase in monolayer moisture (M0) content with increasing plasticizer concentration and the highest M0 value was observed for glycerol-plasticized film. Added plasticizers were found to be effective in providing desirable flexibility in terms of elongation to HPMC film which is beneficial for coating and shrink wrap packaging application but adversely affect the tensile strength and transparency of film. Henderson and Oswin models were selected as the best fit model to the experimental sorption data based on AIC values. The findings from the current study would serve in selection of suitable plasticizer for HPMC-based film/coating in food packaging applications.

Torrefaction of Agricultural and Wood Waste: Comparative Analysis of Selected Fuel Characteristics

Abundant biomass is a potential energy source. However, it possesses several challenges when considered for energy applications. Torrefaction, a thermal pretreatment process can improve the properties of biomass as energy source. This study focused on comparing effect of torrefaction operating parameters on agricultural and wood wastes properties as fuel. The physiochemical properties, composition, moisture-biomass interaction and ash melting behavior were determined. The result show that higher torrefaction temperature and longer residence time increased lignin content, reduced hemicellulose and cellulose content. The moisture uptake of torrefied biomass was reduced in the range 2.47–9.94% compared with raw biomass depending on torrefaction temperature that indicate torrefied biomass was more hydrophobic than raw biomass. The moisture adsorption isotherm curve shows type II isotherm based on the Brunauer-Emmett-Teller’s (BET) classification and was best described by the Oswin model. In addition, torrefaction treatment showed significant influence on the melting behavior of the biomass ash. Especially for agricultural wastes, the fouling tendency shifted from serious range to low range with torrefaction treatment. Torrefaction showed promise for improving fuel characteristics of the studied biomass.

Evaluation of storage stability of dried powdered coriander, parsley and celery leaves based on the moisture sorption isotherms and glass transition temperature

The aim of study was to evaluate the storage stability of microwave-vacuum dried (MWVD) and hot air convective dried (HACD) powdered coriander, parsley and celery leaves based on their moisture sorption isotherms and glass transition temperatures (Tg). Dried coriander, parsley and celery leaves were powdered and kept at a storage temperature (TS) of 20 °C for 10 weeks with a water activity ranging from 0 to 0.813 until equilibrium was reached. The values of coefficient of determination (R2 > 0.99) and percentage global relative square error of the approximation (4.9<GRSE<11.3%) indicate that Guggenheim-Anderson-de Boer (GAB), Peleg, Lewicki, Curie and Oswin models well described the relationship between water activity (aw) and the equilibrium moisture content (EMC) of dried materials. The variations in Tg vs. aw or EMC were adequately predicted by linear, square, polynomial, Khalloufi, Gordon-Tylor and Jenckel-Heusch models (R2 > 0.81; 2.95<GRSE<43.5%). For the optimum range of aw (0.2<aw < critical aw), dried powdered coriander, parsley and celery leaves showed the highest stability at EMC from 0.028 to 0.061, 0.022 to 0.074 and 0.027–0.064 g H2O/g DM, respectively. The optimum TS of dried powdered coriander, parsley and celery leaves was from 57.8 to 20.0, 61.3 to 20.0, and 69.8 to 20.0 °C, respectively.

Moisture Sorption Characteristics as Influenced by Application of Hurdles in Dambu-nama Production

Moisture transfer characteristics of dambu-nama (DN) as influenced by addition of citric acid, salt and sugar as hurdles were investigated. Four products comprising DN with 0.1% citric acid + 2% salt and 2% sugar (DNC0.1); DN+ 0.2% citric + 2% salt + 2% sugar (DNC0.2); DN + 0.3% citric acid +2% salt + 2% sugar (DNC0.3) and a control DN without citric acid , salt or sugar (DNC0) were produced and subjected to moisture sorption studies at different temperatures (30, 40, 50 and 60oC) and relative humidities of(10-96%). Incorporation of the hurdles into dambu-nama resulted in increase in monolayer moisture contents, surface areas, net isoteric heats and entropy of sorption. The isotherms obtained were best described by the Henderson model followed by the GAB and Oswin models. The hurdles also resulted to a J-shaped isotherm instead of the sigmoidal isotherm shape.

Temperature effects on sorption behaviour of compressed and cement-stabilised earth blocks

This paper seeks, as a part of Algerian policy, to encourage the reconstruction of the ground in order to achieve economic reconstruction and the safety of inhabitants and the environment. The study focuses on the hygrothermal behaviour of compressed and stabilised earth blocks that can be used in different climate zones, like the south of Algeria, where the temperature is up to 50°C in summer, and the coastal towns, where humidity exceeds 80%. Accordingly, an experimental study has been conducted to determine the influence of temperature on the sorption isotherms for compressed and stabilised earth blocks stabilised with 6% of cement. The sorption isotherms were measured at temperatures of 10, 23, 30, 40 and 50°C. Twelve equations have been fit to the experimental isotherms to find the one that gives the best agreement. An experimental model was then developed based on the Oswin model describing the dependence of temperature on the sorption characteristics of compressed and stabilised earth blocks. The results show a significant influence of the increase in temperature on the hygrothermal behaviour, in particular a reduction of 11% in the equivalent water content between 10°C and 50°C.

Isothermal adsorption modelling of pupuru flour

The amount of moisture adsorbed by stored food products usually varies with temperature and relative humidity at a constant pressure. This research was carried out to determine the sorption isotherm behaviour of pupuru flour in the temperature and water activity (aw) ranges of 10−50 oC and 0.10−0.93 using gravimetric method. The Guggenheim-Anderson-De Boer (GAB), Brunauer-Emmett-Teller (BET), Oswin and Smith sorption equations, formulated for the sorption characterization of starchy foods, were used to constitute the models. The results show that the sorption isotherm curve is similar to a Type II classification typical of starchy foods. Also, the sorption parameters (Mo, C and K) were generally higher for the products stored at 10 oC and 0.10 aw. The parameter K decreases with an increase in the temperature for the GAB and the Smith models, but remains inconsistent for the Oswin model. The Mo increases with an increase in the temperature for the GAB and Smith models. The GAB, Oswin and Smith models were generally adequate and valid with an MSE&amp;lt; 10% and a high degree of fitness (R2 and R2adj &amp;gt; 90%). This indicates their ability to predict the sorption isortherm characteristics of the pupuru flour within its range of the aw and the storage temperature.

Adição de lecitina de soja como adjuvante de secagem na obtenção de cajá em pó

&lt;p&gt;Various drying techniques can be applied, depending on the raw material you want to dehydrate and what you want to obtain. One way to assess whether the dehydration method was efficient is through sorption isotherms. The objective of the work was to analyze and compare the adsorption isotherms of the cajá pulp powder obtained by atomization, with the use of maltodextrin (Test A) and maltodextrin and soy lecithin (Test B). The mathematical models of GAB, BET, Henderson and Oswin were used to represent the isotherms at 25, 30, 35 and 40 ° C. The results showed that the addition of lecithin gives a statistically different powder (p &amp;lt;0.05) from a powder without addition in relation to soluble solids, total sugars and its color. The BET model was the one that best fit Test A, and the Henderson model was the one that best fit Test B, which proved to be Type III in the J format. It was also observed that the addition of soy lecithin provided greater water adsorptio, which demonstrates that the product should be stored in a location with low levels of relative humidity or in packaging with low permeability.&lt;/p&gt;

Desorption isotherms and thermodynamic properties of Solanum gilo

Solanum gilo is a plant belonging to the family Solanaceae with a probable origin in Africa. It was introduced to Brazil by workers. The fruit is cultivated by small producers in Brazil and it is a source of food for the low-income population. Its seeds are harvested with high moisture contents, and the drying process is necessary. Sorption isotherms consist of the relation between water activity (aw) and moisture content of an agricultural product at a constant temperature. This information contributes to the drying process, thus favoring an increased longevity of agricultural products, such as seeds. This research aims to determine the desorption isotherms of Solanum gilo seeds and calculate their thermodynamic properties (enthalpy, entropy and Gibbs free energy). Sorption experiments were performed by the gravimetric static method using saline solutions. Several mathematical models were fitted to the experimental data, and the selection of the best model was performed by statistical criteria. Equilibrium moisture contents were obtained at 10, 20 and 30°C and at water activities between 0.111 and 0.985 (decimal). The modified Oswin model best represents moisture desorption isotherms of Solanum gilo seeds under the studied conditions. The energy required for the process was 0.22-555.68 kJ kg-1. The latent heat of vaporization (L), the enthalpy (Qst), the entropy (ΔS) and the Gibbs free energy (ΔG) increased with the reduction of the equilibrium moisture content of seeds. The theory of isokinetics is valid for the desorption process.

Moisture sorption characteristics and quality changes during storage in defatted soy incorporated maize-millet based extruded product

Moisture sorption isotherms and changes in quality of extruded products during storage were carried out in this experiment. Sorption of extruded product was investigated at four different temperatures 30, 40, 50 and 60 °C using static method. The optimized composite blend of maize: finger millet: defatted soy: elephant foot yam in the ratio of 40:30:20:10 was used to develop extruded product by using twin screw extruder at feed moisture 14% (wb), barrel temperature 110 °C and screw speed 301 rpm. The sorption isotherms were found to be Type II curves for all the experimental temperatures. The data was analyzed by sorption models of GAB, Smith, BET, Caurie, Oswin and Iglesias and Chirife. Regression analysis was performed to find the model constants. Goodness of fit was determined by statistical parameters R2, %RMSE and %P. GAB model was found to be best fitted. The storage study of extrudates packed in LDPE, HDPE, Al foil and MPET were done at accelerated condition (40 °C and 90% RH). Product moisture, hardness and crispness of the products were found to be varied significantly at 5% level with storage period. MPET was found to be best packaging material for extruded products with longer storage life.

Moisture adsorption isotherms of dried Ficus deltoidea herbal leaves

Ficus deltoidea is a popular traditional medicine that widely used to treat various kind of diseases because of its high number of phenolic contents. In order to meet the demand of the high usage in the market, it is very important to study the behaviour of the dried herbal leaves to prolong the shelf life during storage. Hence, the study of moisture adsorption isotherm is one of the crucial parameters to minimize the deterioration of the quality. The moisture adsorption data of dried Ficus deltoidea leaves were monitored using gravimetric static method. Six different saturated salts such as potassium chloride, sodium chloride, sodium nitrate, magnesium nitrate, magnesium chloride and potassium acetate were utilized in this experiment. The equilibrium relative humidity range was setup between 23 to 86 %. Three different temperatures of 8, 30, 40 °C were used as a treatment of experiment. From the final results, it is clearly claimed that the moisture adsorption isotherm data exhibited J shaped and type III of Brunauer, Emmet and Teller (BET) classification. In addition, the results of experimental data as shown that the best mathematical model fitted to Peleg model compared to GAB and Oswin models.

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

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.

Models of Moisture Sorption Isotherm and The Estimation of Red Ginger Powder Shelf Life in Various Packaging Materials

Abstract&#x0D; In the processing, the red ginger powder was dried at 50°C. Red ginger powder is hygroscopic, so it is easy to absorb moisture. This research aims to determine (i) the isothermic absorption curve model in red ginger powder with different fineness modulus and (ii) the expiration date using the critical moisture content method in various types of packaging materials. Moisture sorption isotherm of red ginger powder was determined by the static gravimetric method at 300C. The relationship equilibrium moisture content between relative humidity (RH) is described by the Hasley, Chen-Clayton, Henderson, Caurie, and Oswin Models. The Estimated shelf life is determined using the ASLT (accelerated shelf-life testing) method and calculated using the Labuza model with a critical water content approach. The results obtained that moisture sorption isotherm red ginger powder has sigmoid shape a type II. Henderson is the model that illustrates the accuracy of the ISA curve of red ginger powder of 60 mesh particle size while the Chen-Clayton Model illustrates the accuracy of the ISA curve of red ginger powder of particle size of 80 mesh. The shelf life of red ginger powder is 60 mesh particle size and using HDPE, PP, and aluminum foil packaging which is stored at 75% RH and 300C temperature is 118.85 days, 467.63, and 609.26 days, respectively. The shelf life of red ginger powder 80 particle size is 148.17 days, 582.98 days and 759.54 days.&#x0D;

Effect of cultivar type, maturation level, and sulfuration on sorption isotherms of apricots

Turkey is the leading country in fresh and dried apricot production and export worldwide. Moisture sorption isotherms illustrating sorption behavior of apricots can be used to estimate endpoint of drying time and safe storage moisture content for dried apricots. In this study, sorption isotherms for two apricot cultivars (Hacıhaliloğlu and Kabaaşı) at three maturation levels were developed by static gravimetric method over a range of 22.6%–84.32% RH at 25°C. Moisture sorption data were fitted to GAB, BET, Halsey, and Oswin models to estimate moisture contents of apricots. The type of cultivar, maturation level, and sulfuration had no significant effect on moisture sorption characteristics of apricots (p > .05). Best fitting GAB model exhibited a critical moisture content of 20% (wb) for dried apricots at aw 0.65 for safe storage and drying process was suggested to be stopped when the apricots achieved moisture content of 18%–19% wb. Practical applications This study revealed that two apricot cultivars showed similar sorption behaviors at constant temperature (25°C). Apricot maturation level and sulfuration process did not significantly affect adsorption and desorption behaviors. For appropriate handling of dried apricots, and reducing losses during storage, HHO and KA apricots should be dried to 18%–19% wb moisture content prior to packaging and kept below 20% wb moisture content for maintaining safe storage. The results of this study are expected be useful for improving dried apricot production and storage in practice.

Improving Photocatalytic and Antibacterial Properties of Zein/Polyvinyl Alcohol Polymer Composite Film by Dispersing TiO2 Nano Particles

Zein/polyvinyl alcohol/nano-TiO 2 composite film was effectively blended using a solution casting method. Mechanical, photocatalytic, and antibacterial properties of the composite film were evaluated. The breaking elongation of the composite film increased up to the maximum loading of 0.4% of nano-TiO 2 . The humidity and moisture content relationship was estimated with standard modified models of Halsey, Oswin, Chung Pfost, and Henderson. It was found that the Halsey model was the most suitable mathematical model to predict the effect of humidity on moisture absorption of zein/PVA/nano-TiO 2 composite film. The dispersion of nanoparticles in the composite film was evidenced by a field emission scanning electron microscope. In addition, the film was thermally stable up to a temperature of 200 o C, indicated by a thermographic analyzer. Methyl orange photocatalytic degradation met kinetics of the 1 st order reaction with a total degraded amount of 92 percent. Moreover, the role of TiO 2 nanoparticles in the composite film has a remarkable effect on the inhibition of gram-positive and negative bacterial growth. The synthesized film can be a possible alternative for production of surface protective packaging material.

Effect of maturity on the moisture sorption isotherm of chili pepper (Mareko Fana variety)

The moisture sorption isotherm at three maturity levels of the Mareko Fana chili pepper variety (red, brown and green) has been studied in this paper. The sorption isotherm was determined based on the standard static gravimetric method using a glycerol-water mixture in a relative humidity range of 10–92% at three temperature levels and nonlinear regression analysis was used to select suitable sorption models. The Clasius - Clapeyron equation was implemented to determine the isosteric heat of sorption of the chili pepper using the experimental equilibrium moisture content at different sorption temperature levels. The results showed that the GAB model was well fitted for green chili pepper, while the OSWIN model described well the brown and red chili variant. There was a difference in net isosteric heat between the adsorption and desorption isotherm of chili pepper maturity. For green chili, the maximum value of the net isosteric heat was 18 kJ mol−1 and 20 kJ mol−1 for adsorption and desorption isotherms, respectively and it decreased exponentially as moisture content increased. The desorption heat was higher than the adsorption heat for each maturity of chili pepper which indicated the existence of hysteresis in the sorption process. In comparison to literature data reported for different chili varieties, Mareko Fana has a lower heat of sorption and monolayer moisture content.

Hygroscopicity of Castor Bean Seeds (Ricinus communis L.)

The hygroscopic balance of castor bean seeds (Ricinus communis L.) assists the proper handling of the product to preserve its water content at the levels recommended for safe storage. The objective of this work was to determine the water adsorption isotherms of castor bean seeds (EVF103 and EVF106) to obtain information on the amount of water that this product adsorb at temperatures of 10, 20, 30, 40oC and water activities between 0.20 and 0.89, as well as adjusting different mathematical models to the experimental data. To obtain the hygroscopic equilibrium, the indirect static method was used, using Hygropalm Model Aw 1 equipment, analyzing castor bean seeds of the genotypes EVF103 and EVF106. The Copace model (for the EVF103) and Modified Oswin model (for the EVF106), according to the statistical parameters and Akaike’s information criterion (AIC) and Schwarz’s bayesian information criterion (BIC) information criteria, represent the hygroscopicity of castor bean seeds in the temperature range of 10 to 40oC. In a same water activity, the water content of the castor bean seeds of the genotypes EVF103 and EVF106 reduces with increasing temperature.

Arbuscular Mycorrhizal Fungi in Tropical Ecosystems: Towards its Management?

The hygroscopic balance of castor bean seeds (Ricinus communis L.) assists the proper handling of the product to preserve its water content at the levels recommended for safe storage. The objective of this work was to determine the water adsorption isotherms of castor bean seeds (EVF103 and EVF106) to obtain information on the amount of water that this product adsorb at temperatures of 10, 20, 30, 40oC and water activities between 0.20 and 0.89, as well as adjusting different mathematical models to the experimental data. To obtain the hygroscopic equilibrium, the indirect static method was used, using Hygropalm Model Aw 1 equipment, analyzing castor bean seeds of the genotypes EVF103 and EVF106. The Copace model (for the EVF103) and Modified Oswin model (for the EVF106), according to the statistical parameters and Akaike’s information criterion (AIC) and Schwarz’s bayesian information criterion (BIC) information criteria, represent the hygroscopicity of castor bean seeds in the temperature range of 10 to 40oC. In a same water activity, the water content of the castor bean seeds of the genotypes EVF103 and EVF106 reduces with increasing temperature.

INFLUENCE OF ALBUMIN ON GUAVA PULP POWDER OBTAINED BY FOAM-MAT DRYING

ABSTRACT Guava is a fruit that stands out for its aroma, intense flavor, vitamins, and minerals. Its availability as a powdered food enhances its commercial applications. This study aimed to evaluate mathematical models for adsorption isotherms and determine the properties and flowability of guava pulp powder obtained by foam-mat drying. The models of GAB, BET, Henderson and Oswin were fitted to determine the isotherms of powders with 4 and 8% albumin, at temperatures of 35°C and 45°C. The powders were evaluated by wall friction angle, flow index, apparent density, and particle microstructure analysis. The best fit to the isotherms was obtained by the GAB model. Wall friction angle ranged from 15.7 to 21.9° and from 13.6 to 20.4° for samples containing 4 and 8% albumin, respectively. Higher densities were observed in the powder containing 8% albumin. The powders were classified as easy flowing when the flow index was between 8.00 and 8.68. The presence of albumin in powders resulted in particles with less rough surfaces, less hygroscopicity, and improved flowability.

Comparative analysis of sorption characteristics of Bulgarian grape seeds and flours and flakes produced by them

The present paper contains a comparative characteristics of results obtained from statics of the sorption characteristics of grape seeds and biologically active products obtained from them - full-fatted flour, defatted flour and full-fatted flakes. The statics of the sorption processes is conducted for three temperatures - 10°C, 25°C and 40°C and eight water activities in the range from 0.112 to 0.868. For all of the examined products the temperature rise leads to a decrease of their sorption capacity. For the description of the equilibrium curves of the examined products the three parametric modified models of Oswin, Halsey, Henderson, Chung-Pfost are used. By the method of the smallest squares, using a programme for nonlinear regression “Statistics”, the coefficients of the used models are calculated, as on the basis of universally used criteria of suitability, a relevant model is recommended for each of the four Bulgarian products. The calculation of the values of the monolayer moisture content (MMC) in water activities below 0.5 is done through linearization of the Brunauer-Emmett-Teller (BET) model. The obtained results for MMC vary within the range from 2.34% to 4.96% dry substance (d.b.) for the processes of adsorption and desorption.