Oswin Equation Research Articles

Water Sorption Isotherm of Ebi Seasoned Potato Chip Model

The aim of this study was to determine the characteristics of the water sorption isotherm of dried shrimp (ebi) seasoned potato chips (ESPC) model and the appropriate equation model. The parameters used were critical parameters for quality degradation such as water content (%), crispness value (hardness force) and hedonic organoleptic analysis. ESPC samples were stored at room temperature, with different humidity conditions, namely 100%, 84%, 75.5%, 43%, 32.4% and 6.90% using water and saturated solution of KCl, NaCl, K2CO3, MgCl2 and NaOH respectively until reaching constant weight. During storage, the samples were analysed its water content, hardness force values and texture hedonic scores. The critical moisture content and critical texture of ESPC is 5.82% and 4.45N, i.e., when the the texture hedonic scores at least 4.0. The Water Sorption Isotherm curve of ESPC was examined with equation models of Hasley, Chen-Clayton, Henderson, Caurie and Oswin. The fittest model is determined by using Mean Relative Determination (MRD) of which the lowest value of the obtained MRD to be considered as the best model. This study revealed that best equation model for describing the water sorption isotherm of ESPC model was the Oswin equation model.

Isotherm moisture sorption of composite desiccant made from rice husk biomass

The behavior of isotherm moisture sorption form rice husk-CaCl2 composite desiccants was studied. The desiccant composite in various treatments was tested for its isotherm sorption using gravimetric method. Saturated solution of LiCl, CH3COOK, MgCl, K2CO3, NaBr, NaNO2, NaCl, KCl, and K2SO4 were used to obtain the moisture of 11 %, 22 %, 32 %, 44 %, 56 %, 64 %, 75 %, 84 % and 97 %. Water activity produced from these saturated salt solutions was measured using aw meter. The equilibrium moisture data was then fitted into several isothermal equation models that have been used and tested in several literature including the model of Courie, Oswin and Chen Clayton. This rice husk composite desiccant had exposed a J shape curve of equilibrium water content with a boundary zone A of aw 0.2 and zone B of aw 0.67. Based on the isothermic absorption curve, the Oswin equation model was able to predict the results of research with R2 of 0.96, 0.89 and 0.97, respectively for temperature of 30, 40 and 50°C. This rice husk desiccant was able to absorb water vapor at low RH. It means that this desiccant is promising to be used for low water content or hygroscopic product such as flour based product, food flavor powder, chili powder, palm sugar and other products.

Effects of Post-Harvest Conditions on Sorption Isotherms of Soybeans

Abstract. This study focuses on the modeling of sorption characteristics of three varieties of soybeans (Akras R2, Lono R2, and Podaga R2). Three pretreatments related to post-harvest conditions were tested on the soybean varieties: (1) freshly harvested soybeans, (2) soybeans subjected to three drying and wetting cycles, and (3) soybeans subjected to three freezing and thawing cycles. The adsorption and desorption experiments were conducted at 5°C, 10°C, 15°C, 20°C, 25°C, and 30°C using a dynamic equilibrium relative humidity (ERH) apparatus. Equilibrium moisture content (EMC) and the corresponding ERH were measured. The parameters calculated for the modified Halsey equation are applicable for storage temperatures above 10°C in the relative humidity (RH) ranges of 10% to 80% for desorption and 30% to 80% for adsorption. No significant differences were found in sorption isotherms among the soybean varieties. However, the soybean varieties responded differently to the different pretreatments (i.e., drying/wetting and freezing/thawing cycles). The adsorption isotherms of Akras and Lono soybeans showed significant differences at 10°C to 30°C when subjected to drying and wetting cycles, while Akras and Podaga soybeans showed significant differences in the same temperature range when subjected to freezing and thawing cycles. The effect of drying and wetting cycles on the desorption isotherms was found only for Akras soybeans at 10°C and 15°C below 63% and 71% RH, respectively, and for Lono soybeans at 25°C and 30°C above 69% RH for both temperatures. In general, the effect of both pretreatments on the sorption isotherms of soybeans was a reduction in EMC of up to 20%, when compared to fresh samples at selected storage temperatures. The findings of this study serve as a primary tool for developing a lookup table for safe storage guidelines for soybeans. Keywords: Equilibrium moisture content, Equilibrium relative humidity, Halsey equation, Oswin equation, Soybeans.

Effect of Drying Systems on the Parameters and Quality of Dried Basil

The main aim of this study is to investigate the possibility of drying the basil plants under different conditions. Fresh basil was dried using different systems: sun-drying, shadow-drying, room-drying, solar-drying and oven-drying systems. Weight losses, moisture content and oil content were recorded. Drying parameters were studied to determine the equilibrium moisture contents (EMC) using different models. The obtained results indicated that the accumulated weight loss of basil plants increased from 3.57 to 83.76, 2.12 to 70.48, 0.72 to 82.07, 0.44 to 84.34 and 1.29 to 84.90 %, for sun-drying system, shadow-drying system, room-drying system, solar-drying system and oven-drying system, respectively. The moisture content of basil plants decreased from 515.95 to 6.91, 490.18 to 6.59, 479.97 to 4.66, 538.02 to 0.93 and 565.40 to 5.40 % d.b. for sun-drying system, shadow-drying system, room-drying system, solar-drying system and oven-drying system, respectively. The highest value of equilibrium moisture contents were 13.25 and 35.16 % at 10 and 90 % equilibrium relative humidity was found from Modified Chung-Pfost equation under room system. The lowest value of equilibrium moisture contents were 0.91 and 16.58 % at 10 and 90 % equilibrium relative humidity was found for modified Oswin equation for oven system. The basil oil content values were 2.3, 2.5, 2.9, 2.7 and 2.0 % for the sun-drying, shadow-drying, room-drying, solar-drying and oven-drying, respectively.

FREEZE DRYING AND MOISTURE ADSORPTION KINETICS OF KEFIR POWDER

Freeze drying and moisture adsorption behaviour of kefir powder were investigated by fitting the experimental drying data to ten thin layer drying and sorption isotherm models. Moisture adsorption isotherms of kefir powder were determined at 5-35°C and within the range of 0.11–0.88 water activity. By statistical comparison of the values, Midilli et al. was found to be the best model describing the freeze drying behaviour. The GAB and Oswin equations gave the closest fit to the adsorption data over the tested range of temperatures and water activities. Additionally, adsorption isotherms data were used to determine the thermodynamic properties such as isosteric heat, sorption entropy and Gibbs free energy. The enthalpy entropy compensation was valid for the adsorption process and showed that the process was controlled by the enthalpy. Gibbs free energy was negative at all of the tested temperatures, which indicates that moisture adsorption of kefir powder was a spontaneous process.

Moisture sorption isotherm characteristics of moringa seed at two different temperatures

The moisture sorption isotherm experiments of moringa seed were conducted in a climate test chamber (CTS), the relative humidity of which is regulated by an atomizing humidifier, at temperatures of 25 and 60°C and a relative humidity range of 25 to 95%. The sorption isotherms were sigmoidal in shape (Type II). The experimental sorption data was applied to various isotherm equations (BET, Oswin, Modified Oswin, GAB, MGAB, Fraction Linear (FL), Modified Chung-Pfost and Modified Henderson) and were evaluated for their ability to fit the experimental data using non-linear regression techniques. Comparisons were made on the basis of coefficient of fit (R2), mean relative error (MRE) value, standard error of moisture (SEM) and residual plots. The comparison showed that the Fraction Linear (FL) equation was the most appropriate equation followed by the Modified Oswin equation for modeling the EMC/ERH (water activity) adsorption isotherms of moringa seed. The adsorption EMC data obtained in this work agree with previous published data and therefore will be helpful for future work on drying and for predicting the quality change during the storage of moringa seed.

Basil Drying Performance and Quality under Different Drying Systems

The main aim of this study is to investigate the possibility of drying the basil plants under five different drying systems. The obtained results indicated that the accumulated weight losses of basil plants were 77.43, 74.00, 70.48, 74.92 and 77.99 %, for sun-drying system, shadow-d rying system, room-drying system, solar-drying system and oven-drying system, respectively at the end of experimental period. The highest values of equilibrium moisture contents were 13.94 and 37.01 % at 10 and 90 % equilibrium relative humidity was found from Modified Chung-Pfost equation under room system. The lowest values of equilibrium moisture contents were 0.83 and 15.07 % at 10 and 90 % equilibrium relative humidity was found for modified Oswin equation for oven system. The basil oil content values were 5.918, 7.911, 8.472, 6.547 and 5.230 % for the sun-drying, shadow-drying, room-drying, solar-drying and oven-drying, respectively.

Sorption equilibrium moisture and isosteric heat of adsorption of Chinese dried wheat noodles

Equilibrium moisture content (EMC) data for dried wheat noodles of ten Chinese varieties were collected by a gravimetric method at 11–96% equilibrium relative humidity (ERH) and 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C. Five models were fitted to the sorption data, namely the modified Chung Pfost equation (MCPE), modified Henderson equation (MHE), modified Guggenheim Anderson deBoer equation (MGAB), modified Oswin equation (MOE), and a polynomial equation. The best fitting equations were MGAB and the polynomial equation. At a constant ERH, the EMC decreased with increasing temperature, despite the minor effect of temperature on the sorption isotherms of dried noodles. Initially, the isosteric heats of adsorption for dried wheat noodles decrease rapidly with increasing sample moisture content (m.c.); however, after the moisture content is more than 15% of the dry basis (d.b.), they decrease slowly with increasing m.c. The heat of vaporization of Chinese dried wheat noodles approaches the latent heat of pure water at a moisture content of ∼20% d.b., which is ∼2500 kJ/kg. The isosteric heats of sorption of Chinese dried noodles predicted by MCPE and MHE models at lower temperatures were higher than those at higher temperatures. When the equilibrium relative humidity (ERH) is 60%, the safe-storage moisture content of Chinese dried wheat noodles are 11.74% and 11.57% d.b. at 25 °C and 35 °C, respectively. Among ten varieties of dried wheat noodles, the egg-flavoured noodle had the highest onset temperature (To), peak temperature (Tp), and conclusion temperature (Tc) of gelatinization, but the golden-silk egg noodles had the highest peak enthalpy of gelatinization. The gelatinization To, Tp, and Tc of golden-silk egg noodles were the lowest. Most of the ten varieties of dried wheat noodles demonstrated similar thermal properties and hygroscopic behaviour.

피속 잡초 종자의 등온흡습곡선 특성

The equilibrium moisture contents (EMC) in seeds of four Echinochloa (E. crus-galli var. crus-galli, E. crus-galli var, echinata, E. crus-galli var. praticola, E. esculenta) were measured at 20oC with equilibration over a series of lithium chloride solutions with relative humidities ranging from 0.11 to 0.8 to determine sorption isotherms and safe storage relative humidity. Standard seed sorption isotherm models i.e. modified Henderson, modified Chung-Pfost, modified Halsey, modified Oswin and Guggenheim-Anderson-deBoer (GAB) equations were adopted to evaluate the goodness of fit to sorption isotherms. This study indicated that EMC of seeds was significantly different in four Echinochloa species at various relative humidity. The modified Oswin equations for E. crus-galli var. crou-galli, E. crus-galli var, echinata, E. esculenta and GAB equation for E. crus-galli var. praticola were adequate models for the EMC data. Seeds of four Echinochloa species have monolayer moisture contents when stored at RH < 0.1. These results show that seed moisture isotherm model should be selected according to genetic variation.

Sorption behaviour of papayas as affected by compositional and structural alterations from osmotic pretreatment and drying

Moisture sorption dynamics and isotherms of fresh, osmotically-pretreated and dried papayas at temperatures of 30, 50 and 70°C and water activity in the range of 0.113–0.907 were investigated. Chemical composition as well as volume, density, porosity and microstructure of the fruits were analysed. Results showed that the time required to reach equilibrium moisture content was mainly dependent on temperature, water activity level and processing method. The difference in moisture sorption characteristics between fresh, pretreated and dried papayas was attributed to (i) changes in the contents of sugars after osmotic dehydration and (ii) structural modifications caused by drying, which were corroborated by examination of micrographs. The differences in sorption were also proven by the selected isotherm models. The modified Halsey equation described the sorption behaviour of the pretreated and dried papayas, whereas the untreated, fresh samples were better predicted by the modified Oswin equation. Further indication that osmotic pretreatment and drying influenced the interaction between the sorption sites and water molecules was imparted by the values of isosteric heat of sorption (Qst) for fresh and dried papayas at different temperatures.

Modeling the equilibrium moisture content (EMC) of Miscanthus sinensis, miscane, energy cane, and energy sorghum

Understanding of moisture sorption isotherms of bioenergy crops is critical to monitoring their stability and quality during harvest, handling, transportation, and storage. Relationships between the moisture content (EMC) and equilibrium relative humidity (ERH) of four biomass crops – Miscanthus sinensis, miscane, energy cane, and energy sorghum – were determined at 15, 25, and 35°C. Type II and type III isotherm characteristics were observed in all samples. The Henderson, modified Henderson, modified Chung-Pfost, modified Halsey, modified Oswin, and modified GAB models were applied to the individual energy crop’s sorption isotherm data and a global isotherm model for the four energy crops was developed. Results showed that the modified Oswin model best fit the sorption behavior of the individual crops (0.974⩽R2⩽0.997 and 0.72% wet basis (w.b.)⩽standard error (SE)⩽1.91% w.b.) and for a global isotherm model of these crops (R2=0.973 and SE=1.96% w.b.). When the soluble sucrose content (0.00–15.9%) of the energy crops were included the global isotherm model based on the modified Oswin equation, overall performance improved (R2=0.979 and SE=1.75% w.b.).

Equilibrium relative humidity method used to determine the sorption isotherm of autoclaved aerated concrete

The sorption isotherm of porous building material is basic information needed for the design and maintenance of materials. The equilibrium moisture content (EMC) method is used to determine this physical property. In this study, the equilibrium relative humidity (ERH) method was used to determine the adsorption data for autoclaved aerated concrete at seven temperatures and found that the ERH method could be used to determine the sorption data within a short time. Comparing with previous published data, no significant difference could be found at humidity >20%. Two different sizes of samples (small and large) revealed the same EMC data throughout the whole relative humidity (RH) range. The Oswin equation was the best ERH model for adsorption isotherm data. A temperature term could be incorporated into model for the adsorption data. Sorption isotherm data for other building materials could be determined with the ERH method.

Sorption Isotherms for Triticale Seed

<abstract> <bold><sc>Abstract.</sc></bold> Triticale is being evaluated as a substitute for corn in animal feed and as a forage crop for Florida. Storage of triticale seed is difficult in Florida’s hot and humid climate, and more information about the relationships between equilibrium moisture content (EMC) and equilibrium relative humidity (ERH) at constant temperature (sorption isotherms) of triticale is needed to develop improved storage methods. Therefore, the primary research objective was to measure the EMC for triticale seed at different ERH values at three different constant temperatures (5°C, 23°C, and 35°C) using six desiccation jars containing different saturated salt concentrations. The secondary objective was to determine the best fit equation describing these relationships. The six saturated salt solutions provided relative humidity (RH) values of 11%, 23%, 33%, 58%, 75%, and 84% at 25°C. An average of ten weeks was required to reach equilibrium when the initial moisture content (MC) of the seed was 13.35% (wet basis). The results of this experiment were used to develop three prediction equations, (modified Henderson, modified Chung-Pfost, and modified Oswin equations) representing the relationship between ERH and EMC. The results show that the modified Chung-Pfost equation represented this relationship most accurately, with a standard error of 2.4% and a coefficient of determination obtained from the scatter plot for the predicted vs. measured RH (R²) equal to 0.99. Overall, this result will aid the development and improvement of drying and storage methods for triticale seed.

Determination of the moisture sorption behavior of osmotically dehydrated mackerel fillets by means of binary and ternary solutions

In this study, the moisture sorption isotherm of osmotically dehydrated mackerel fillets (Scomber japonicus) was experimentally determined. The fillets were osmotically dehydrated with solutions of salt (NaCl) (120 and 180 g per liter of solution) or in combination with sugar (350 to 700 g per liter of solution). The sorption isotherms were determined using the static gravimetric methodology with six salts for the water activity range of 0.33-0.98 at 5 degrees C and 25 degrees C. All the sorption curves were found to be type III. Temperature and the final tissue salt content had significant (p < 0.05) effects on the sorption isotherms. A regression program was used to fit the Halsey, Oswin and Smith moisture sorption isotherm models. Oswin equation gave the best fit for the whole range of water activity and temperatures. The Smith equation only presented valuable results for the mackerel fillets samples with the higher salt content.

Sorption isotherms and isosteric heats of sorption of Malaysian paddy.

Understanding the water sorption characteristics of cereal is extremely essential for optimizing the drying process and ensuring storage stability. Water relation of rough rice was studied at 20, 30, 40 and 50°C over relative humidity (RH.) between 0.113 and 0.976 using the gravimetric technique. The isotherms displayed the general sigmoid, Type II pattern and exhibited the phenomenon of hysteresis where it was more pronounced at lower temperatures. The sorption characteristics were temperature dependence where the sorption capacity of the paddy increased as the temperature was decreased at fixed (RH). Among the models assessed for their ability to fit the sorption data, Oswin equation was the best followed by the third order polynomial, GAB, Smith, Chung-Pfost, and Henderson models. The monolayer moisture content was higher for desorption than adsorption and tend to decrease with the increase in temperature. Given the temperature dependence of the sorption isotherms the isosteric heats of sorption were calculated using Claussius-Clapeyron equation. The net isosteric heats decreased as the moisture content was increased and heats of desorption were greater than that of adsorption.

Moisture Sorption Isotherms of Lentil Extrudates

Abstract The equilibrium moisture contents (EMC) were determined for lentil extrudates produced under different processing conditions at 25°C and eight relative humidity (RH) in the range of 0.113 – 0.902. It was established that for the ten extruded samples the EMC values at the same RH were not statistically equal. Four models – Chung-Pfost, Halsey, Oswin, and Henderson equations were applied for analyzing the experimental data. The Oswin model was most suitable for describing the relationship between the EMC and RH.

Moisture sorption isotherms and isosteric heat of sorption of leaves and stems of lemon balm (Melissa officinalis L.) established by dynamic vapor sorption

The equilibrium moisture contents (MC) of leaves and stems of lemon balm (Melissa officinalis L.) were determined separately at temperatures of 25, 35 and 45 °C over a stepwise increase of relative humidity (RH) ranging from 3 to 90% by an automatic, gravimetric analyzer (DVS system). Equilibrium was achieved within 6 h for most of the target values of relative humidity. The equilibrium moisture content of leaves was significantly higher than that of stems (p < 0.05). Differences in moisture sorption capacity between the leaves and stems can be attributed to chemical composition and structure of the tissues. Five three-parameter moisture sorption models (modifications of Chung–Pfost, GAB, Halsey, Henderson and Oswin) were tested for their effectiveness to fit the experimental sorption data. The modified Oswin equation was found to be the best model to describe the adsorption isotherms of both leaves and stems of lemon balm. The recommended MC values of leaves and stems for microbial safe storage at 25 °C were 0.124 and 0.113 kg water per kg dry solids, respectively. The net isosteric heat of sorption was computed from the predicted sorption data by applying the integrated form of the Clausius–Clapeyron equation.

Equilibrium Moisture Contents of Pureline, Hybrid, and Parboiled Rice Kernel Fractions

The effects of temperature and relative humidity on the equilibrium moisture contents of rough rice, brown rice, and head rice from non-parboiled pureline cultivars Wells (long-grain) and Jupiter (medium-grain), hybrid cultivar CL XL730 (long-grain), and a parboiled rice (long-grain) of unknown cultivar, were investigated. In addition, equilibrium moisture contents of broken kernels, rice bran, and rice hulls of Wells cultivar were also investigated. Air conditions were maintained at temperatures of 10C to 60C, and relative humidities of 10% to 70% to measure kernel-fraction moisture contents. For each air condition, rough rice and constituent fractions were allowed to equilibrate, after which the equilibrium moisture content of each fraction was measured. Rice hulls attained the lowest equilibrium moisture content followed by rice bran, brown rice, broken kernels, and head rice; this held for both parboiled and non-parboiled samples. Five, three-parameter equations, namely, the Modified Henderson, Modified Chung-Pfost, Modified Halsey, Modified Oswin, and Modified Guggenheim-Anderson-DeBoer were evaluated for their ability to describe the sorption data of each kernel fraction. The Modified Chung-Pfost and Modified Guggenheim-Anderson-DeBoer equations were the most suitable for describing equilibrium data of rough rice, brown rice, broken kernels, and head rice of both parboiled and non-parboiled samples, followed by the Modified Oswin and Modified Henderson equations. The Modified Oswin equation was the most suitable for rice bran and hulls. The measured equilibrium moisture content of rough rice was closely predicted by the weighted average equilibrium moisture content of the kernel fractions.

Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats

Adsorption and desorption isotherms of quinoa seeds (Chenopodium quinoa Willd.) were measured using the static gravimetric method at three temperatures (20, 40 and 60 °C). Water activity ranged from 0.118 to 0.937. The moisture sorption behaviour of quinoa was temperature dependent, as indicated by a decrease in equilibrium moisture content, at all levels of aw, with increasing temperature. Eight mathematical equations available in the literature were used to model the experimental data, namely, GAB, BET, Caurie, Henderson, Oswin, Halsey, Smith and Iglesias–Chirife. All the equations showed generally a good fit; however, the Iglesias–Chirife and Oswin equations were considered the best to predict the experimental data for both isotherms. Effect of temperature on model parameters was analysed and studied through an Arrhenius-type equation. The net isosteric heats of desorption and adsorption were determined by applying the Clausius–Clapeyron equation resulting in 69.24 kJ mol−1 for desorption and 61.26 kJ mol−1 for adsorption. The experimental heat data were satisfactorily modelled by Tsami’s equation.

Hydrogen Adsorption on Pd- and Ru-Doped C60 Fullerene at an Ambient Temperature

Palladium- and ruthenium-doped C(60) fullerene compounds were synthesized by incipient wetness impregnation of C(60) fullerene with the corresponding metal acetylacetonate precursors. Transmission electron microscopy (TEM) imaging of the metal-doped C(60) fullerene samples showed different dispersion morphologies of palladium and ruthenium particles on the C(60) matrix. Raman spectra revealed a drastic decrease in peak intensity followed by disappearance of several bands indicating the distortion of the C(60) cage structure. The amorphous nature of the C(60) fullerene compounds was confirmed by the X-ray diffraction study. Hydrogen adsorption amount of 0.85 wt % and 0. 69 wt % on Pd-C(60) and Ru-C(60), respectively, as compared to 0.3 wt % on the pure C(60) fullerene were measured at 300 bar and 298 K. The enhancement in the hydrogen uptakes can be attributed to several factors, including adsorption of molecular H(2) on the defect sites, metallic hydride formation, spillover of hydrogen, and bond formation with atomic hydrogen with different active sites of carbon of host fullerene. The hydrogen adsorption isotherms are of type III and can be correlated by the Freundlich (for Ru-C(60)) and modified Oswin equations (for Pd-C(60) and pristine C(60)).