Effect of Relative Humidity on the Antioxidant Activity of Spray-Dried Banana Passion Fruit (Passiflora Mollisima Baley)-Coated Pulp: Measurement of the Thermodynamic Properties of Sorption

The antioxidant activity of the spray-dried banana passion fruit-coated pulp with maltodextrin10 DE was evaluated throughout 30 days of storage at a temperature of 25°C for different relative humidity values It was influenced by the relative humidity throughout the 30 days of storage. In addition, the sorption equilibria of water for spray-dried banana passion fruit-coated pulp with maltodextrin 10 DE at 25, 35, 45, and 55°C, over a range of relative humidity levels from 0.113 to 0.843, was determined using a gravimetric static method. The isosteric heat and Gibbs free energy were calculated from the sorption equilibrium. The Guggenheim-Anderson-Boer (GAB) and Brunauer-Emmett-Teller (BET) models were tested to fit the experimental data. The GAB model was found to be the most suitable for describing the sorption curves, exhibiting an error smaller than 10% and an r greater than 0.99. The monolayer moisture content values for the sorption at different temperatures that were calculated using the GAB model ranged between 0.05315 to 0.05716 g water/g dry matter. The sorption curves exhibited a Type III behavior. The isosteric heat decreased with increasing moisture content while the Gibbs free energy increased.     

Modeling the moisture sorption isotherms of two‐phase solid olive oil by‐product

The moisture sorption isotherms of two‐phase solid olive oil mill by‐product (SOB) were measured at different temperatures (15–50 °C) in order to thoroughly know the hygroscopic properties of this material. SOB is like a slurry with a high water content (60–70%). It is obtained in the olive oil two‐phase extraction process and is currently used as the raw material for obtaining pomace oil by extraction with hexane; prior to the extraction, drying of the SOB is required. Other uses of SOB are composting, animal feeding and solid fuel; in such cases, the previous drying of the material is also required. Sorption moisture isotherms for the two‐phase SOB were obtained by a static method. Eight models were fitted to the experimental data: BET, GAB, Halsey, Smith, Henderson, Oswin, Ferro‐Fontan and Peleg. The GAB equation was the best option to describe the water sorption behavior of SOB within a very wide range of water activities (0–0.90). A generalized GAB model, in which temperature is taken into account, was obtained by multivariable fitting of the complete set of the experimental isotherms.     

Sorption Isotherms of Vaccum-Fried Carrot Chips

Abstract

The moisture sorption isotherms for carrot chips after vacuum frying were determined using a gravimetric technique at 10, 25, and 40°C and fitted with BET, GAB, Smith, Halsey, Henderson, and Peleg models. A nonlinear least-squares regression program was used to determine the models constants. The Peleg, Halsey, and GAB models were found to best represent the experimental data throughout the entire water activity range.     

Experimental Determination and Modeling of Sorption Isotherms of Tropical Fruits: Banana,Mango, and Pineapple

Abstract

Sorption isotherms of banana, mango, and pineapple have been experimentally found at 40, 50, and 60°C by use of the salt method for a range of water activities from 0.056 to 0.85. The sorption capacity of these fruits increases with the temperature for a given water activity. The experimental curves have been simulated by the GAB and BET models. The BET model ensures a better representation of the experimental results for water activity lower than 0.35 with maximum deviation of 1.0, 1.5, and 2.0 kgw · kgdm^?1 for respectively banana, mango and pineapple. On the contrary, the GAB model enables the representation of the whole desorption isotherms and the estimation of the water content corresponding to monolayer saturation and of the isosteric heat of sorption. It also takes into account the temperature effect. The isosteric sorption heat of the three studied products are deduced from experimental results and empirical correlations are proposed leading to a satisfactorily representation.     

Modeling of Sorption Isotherms of Various Kinds of Wood at Different Temperature Conditions

Adsorption and desorption isotherms of pine, spruce, birch, and willow Salix viminalis v. Orm (2-year stem) under three temperature conditions (20, 50, 75°C) in the range of water activity 0.0–0.9 were studied. In order to describe our experimental data, five models were implemented (GAB, Peleg, Chung-Pfost, Oswin, Halsey) and compared. It was found that GAB and Peleg models provide the best fit to the experimental data. On the basis of GAB modeling, the monolayer moisture content for each kind of wood was calculated. Moreover, the hysteresis phenomenon was investigated. The influence of temperature and wood variety on sorption isotherms was also tested.     

Modeling of Sorption Isotherms of Various Kinds of Wood at Different Temperature Conditions

Adsorption and desorption isotherms of pine, spruce, birch, and willow Salix viminalis v. Orm (2-year stem) under three temperature conditions (20, 50, 75°C) in the range of water activity 0.0-0.9 were studied. In order to describe our experimental data, five models were implemented (GAB, Peleg, Chung-Pfost, Oswin, Halsey) and compared. It was found that GAB and Peleg models provide the best fit to the experimental data. On the basis of GAB modeling, the monolayer moisture content for each kind of wood was calculated. Moreover, the hysteresis phenomenon was investigated. The influence of temperature and wood variety on sorption isotherms was also tested.     

Experimental Determination and Modeling of Sorption Isotherms of Tropical Fruits: Banana, Mango, and Pineapple

Sorption isotherms of banana, mango, and pineapple have been experimentally found at 40, 50, and 60°C by use of the salt method for a range of water activities from 0.056 to 0.85. The sorption capacity of these fruits increases with the temperature for a given water activity. The experimental curves have been simulated by the GAB and BET models. The BET model ensures a better representation of the experimental results for water activity lower than 0.35 with maximum deviation of 1.0, 1.5, and 2.0 kgw · kgdm^-1 for respectively banana, mango and pineapple. On the contrary, the GAB model enables the representation of the whole desorption isotherms and the estimation of the water content corresponding to monolayer saturation and of the isosteric heat of sorption. It also takes into account the temperature effect. The isosteric sorption heat of the three studied products are deduced from experimental results and empirical correlations are proposed leading to a satisfactorily representation.     

Effect of osmosis and ultrasound pretreatment on the moisture adsorption isotherms of quince

The effect of pretreatment osmotic–ultrasonic dehydration on the sorption isotherms of quince was determined by static gravimetric method at temperatures of 30 °C, 45 °C, and 60 °C. The curves obtained can be considered as type II according to the Brunauer–Emmett–Teller (BET) classification. Adsorption data were fitted into seven isotherm models. The best fit of the experimental data was obtained with Peleg for both fresh- and pretreated dried quince slices.Thermodynamic properties such as net isosteric heat, differential entropy, enthalpy–entropy compensation, and spreading pressure were determined from moisture adsorption isotherm data of quince. The net isosteric heat of sorption and differential entropy decreased with increasing moisture contents in an exponential function. A plot of differential heat versus entropy satisfied the enthalpy–entropy compensation theory. The spreading pressure increased with increasing water activity, and decreased with increasing temperature. The value of net isosteric heat, differential entropy and spreading pressure of untreated samples is higher than that of pretreated samples of quince.     

Sorption Isotherms of Vaccum-Fried Carrot Chips

The moisture sorption isotherms for carrot chips after vacuum frying were determined using a gravimetric technique at 10, 25, and 40°C and fitted with BET, GAB, Smith, Halsey, Henderson, and Peleg models. A nonlinear least-squares regression program was used to determine the models constants. The Peleg, Halsey, and GAB models were found to best represent the experimental data throughout the entire water activity range.     

Impact of Sequential Ammonia Fiber Expansion (AFEX) Pretreatment and Pelletization on the Moisture Sorption Properties of Corn Stover

Combining ammonia fiber expansion (AFEX?) pretreatment with a depot processing facility is a promising option for delivering high-value densified biomass to the emerging bioenergy industry. However, because the pretreatment process results in a high moisture material unsuitable for pelleting or storage (40% wet basis), the biomass must be immediately dried. If AFEX pretreatment results in a material that is difficult to dry, the economics of this already costly operation would be at risk. This work tests the nature of moisture sorption isotherms and thin-layer drying behavior of corn (Zea mays L.) stover at 20°C to 60°C before and after sequential AFEX pretreatment and pelletization to determine whether any negative impacts to material drying or storage may result from the AFEX process. The equilibrium moisture content to equilibrium relative humidity relationship for each of the materials was determined using dynamic vapor sorption isotherms and modeled with modified Chung-Pfost, modified Halsey, and modified Henderson temperature-dependent models as well as the Double Log Polynomial (DLP), Peleg, and Guggenheim Anderson de Boer (GAB) temperature-independent models. Drying kinetics were quantified under thin-layer laboratory testing and modeled using the Modified Page's equation. Water activity isotherms for non-pelleted biomass were best modeled with the Peleg temperature-independent equation while isotherms for the pelleted biomass were best modeled with the Double Log Polynomial equation. Thin-layer drying results were accurately modeled with the Modified Page's equation. The results of this work indicate that AFEX pretreatment results in drying properties more favorable than or equal to that of raw corn stover, and pellets of superior physical stability in storage.     

MODELING WATER SORPTION IN OKARA SOY MILK

ABSTRACT

Moisture sorption isotherms of okara soy milk were determined using the gravimetric method in the range 20 - 50 °C. The sorption isotherms exhibited hysteresis along all the water activity range (0·1 - 0·9). The amount of sorbed water increased as the temperature was decreased. The GAB and Halsey models gave a good fit for okara isotherms over the range of water activity 0·1 - 0·9. As temperature increased, GAB k-values increased towards unity where the GAB equation reduces to the BET equation. The influence of temperature on the constants of GAB and Halsey models was evaluated through Arrhenius-type equations. The Clausius Clapeyron equation was used to estimate the isosteric heats of sorption.     

EFFECT OF DRYING METHODS ON MOISTURE SORPTION ISOTHERMS OF FUFU AT THREE TEMPERATURES

ABSTRACT

Moisture sorption characteristics for dried fufu using three drying methods at 25°C, 32°C and 45°C were determined experimentally for water activity ranging from 0.11 to 0.96. At a given temperature and water activity, the rotary dried fufu had the highest equilibrium moisture content while the sun dried had the lowest.

Four linear and four nonlinear sorption models were used to analyze the data. The linear GAB model showed the best fit while the nonlinear Bradley model was the best over the whole range of water activity in their respective groups. Also estimates of the net isosteric heats of sorption and their dependence on moisture content were presented for each product.     

EXPERIMENTAL STUDY OF SORPTION ISOTHERMS AND DRYING KINETICS OF MOROCCAN EUCALYPTUS GLOBULUS

ABSTRACT

The paper deals with sorption isotherms and drying kinetics of Eucalyptus globulus. The sorption isotherms have been determined using a static gravimetric method and then fitted by GAB equation at T = 30, 40, and 50°C over a range of relative humidity from 0.05 to 0.9. The drying kinetics in a solar dryer with an auxiliary heating system are determined. The results show with good reproducibility that temperature is the main factor in controlling the drying rate. The drying rate equation is determined empirically from the characteristic curve of drying.     

Moisture adsorption isotherms and thermodynamics properties of sucuk (Turkish dry-fermented sausage)

Moisture adsorption isotherms of sucuk were determined using the isopiestic method at 10 °C, 20 °C and 30 °C and within the range of 0.2-0.9 water activity. The isotherms of sucuk exhibited Type II behavior according to BET classification. The adsorption data were analyzed using mathematical equations of Halsey, Caurie, Peleg, Smith, Oswin, Henderson, Modified-BET, GAB, Ferro-Fontan and Harkins-Jura. The best fit of experimental data was obtained with Peleg equation in the range of temperatures and water activities investigated. Thermodynamic properties such as differential enthalpy and entropy, enthalpy-entropy compensation, spreading pressure, net integral enthalpy and entropy were determined from moisture adsorption isotherm data of sucuk. The net isosteric heat of sorption and differential entropy decreased with increasing moisture contents in an exponential function. The spreading pressure increased with increasing water activity, and decreased with increasing temperature. The net integral enthalpy decreased with increased moisture content. The integral entropy increased with moisture content, but it was negative in value. The enthalpy-entropy compensation theory was applied to water adsorption of sucuk.     

Moisture Adsorption Isotherms and Glass Transition Temperature of Xanthan Gum

The moisture adsorption isotherms of the xanthan gum were determined at 30–70°C over water activity ranging from 0.11 to 0.94. The moisture adsorption isotherms revealed that the equilibrium moisture content increased with water activity. Increased temperature, in general, resulted in decreased equilibrium moisture content. However, in some cases equilibrium moisture content values increased with temperature. Selected sorption models were tested to describe the adsorption isotherms. Parameters of each sorption model were determined by nonlinear regression analysis. The modified Oswin model gave the best fit for xanthan gum. The isosteric heat of sorption decreased with increase in moisture content and varied between 1.66 and 7.61 kJ/mol. The glass transition temperature decreased with increase in moisture content for xanthan gum.     

SORPTION ISOTHERMS AND THERMODYNAMIC PROPERTIES OF POWDERED MILK

Moisture sorption isotherms of powdered milk were obtained using the gravimetric static method at 30°, 40°, and 50°C. Peleg and Enderby equations were found to be the most suitable models for describing the sorption curves among six well-known tested equations. Thermodynamic properties such as differential enthalpy and entropy of sorption were determined from moisture adsorption and desorption data, using the Clausius-Clapeyron equation. The experimental data showed that enthalpy-entropy compensation theory was applicable to the moisture sorption behavior of powdered milk.     

Sorption Characteristics of Whole Pistachio Nuts (Pistacia Vera L.)

ABSTRACT

Moisture sorption characteristics of whole pistachio nuts were investigated at 10, 20, and 30°C using the static method. The sorption isotherms exhibited hysteresis over the range of 0.10-0.80 water activity which was succesfully interpreted using BET, GAB, Oswin, Smith, Henderson, Chung-Pfost and Halsey mathematical models and from which the BET, GAB and Oswin models were found to give the best fit. Monolayer moisture content of pistachio nuts was determined from BET and GAB equations and the isosteric heat of sorption data were derived using Clausius-Clapeyron equation and presented in graphical form. The information generated can be utilized to optimize the packaging parameters for long term storage of pistachio nuts.     

ADSORPTION ISOTHERMS OF RAW AND ROASTED HAZELNUTS

Adsorption isotherms of raw and roasted (at 100°C, 120°C, 140°C and 160°C) hazelnuts of Tombul variety were determined at 25°C, and over relative humidities ranging from 11 to 90% using the gravimetric static method. Eleven sorption models (GAB, BET, Modified BET, Halsey, Iglesias-Chirife, Oswin, Chung-Pfost, Smith, Kuhn, Harkins-Jura and Caurie) were evaluated by using the linear regression method. GAB (Guggenheim-Anderson-de Boer) model satisfactorily described adsorption characteristics of the samples over the experimental range of study. Monolayer values at 25°C were estimated from the GAB model as 0.0155 kg water/kg dry solid for raw and 0.0100–0.0163 kg water/kg dry solid for roasted hazelnuts. Caurie security moisture content for raw hazelnuts was also determined from Caurie model as 0.048 kg water/kg dry solid.     

市政污泥吸附等温线模型和热力学性质

采用静态重量法测定了市政污泥在30℃、40℃、50℃下的吸附等温线,选用11个常见的数学模型对实验数据进行了拟合并对最佳模型进行了解析,通过净等量吸附热q_st、微分熵ΔS、扩散压力π、净积分焓q_in和净积分熵ΔS_in等指标评价污泥的热力学性质。试验结果表明,在温度恒定时,等温曲线属于Ⅱ型,GAB模型拟合效果最佳,能较好地反映平衡含水量随水分活度的变化。应用Clausius-Clapeyron方程,利用等温线模型计算净等量吸附热和微分熵,随着平衡含水率的增加,净等量吸附热和微分熵明显降低,调和平均温度T_hm与等速温度T_l不等,焓-熵补偿理论成立。在一定的水活度下,扩散压力随温度的升高而减小,在温度恒定的情况下,扩张压力随水分活度增大而升高。净积分焓随平衡含水率的增加而减小,而净积分熵在低平衡含水率时随平衡含水率的增加而减小,在30℃、40℃和50℃时分别达到最小值-75.698J/(K?mol)、-78.987J/(K?mol)和-82.687J/(K?mol),然后呈上升趋势。     

DESORPTION ISOTHERMS OF WATER IN TRIFOLIATE YAM )Dioscorea dumetorum Pax.(

Abstract

Desorption isotherms of water in trifoliate yam (Dioscorea dumetorum Pax) were determined using a dynamic gravimetric method at temperatures of 20°, 34°, 46° and 62°C, in the relative humidity range from 11 to 86% A nonlinear least squares regression program was used to fit the measured data to the Modified Henderson, the Modified Halsey, the Chung-Pfost, and the GAB sorption models. The GAB model gave the best fit. The net isosteric heat of sorption, estimated using the Clasius-Clapeyron equation, ranged from 1412 kJ/kg at a moisture content of 0.05 kg/kg, dry basis, to 325 kJ/kg at 0.20 kg/kg. Results obtained in this study should be important in controlling the water content of yam during processing, handling, packaging and storage.