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Opuntia ficus-indica (Linnaeus) Miller more usually known as fodder palm or nopal belongs to family Cactaceae. In the present study, the drying behavior of the O. ficus-indica cladodes was observed. The study concentrates on comparatively studying two types of commercial drying methods viz., forced convective drying (tray drying) and vacuum drying to dry nopal cladodes at three different temperatures viz. 40, 50 and 60°C. The equilibrium moisture contents for forced convective drying was achieved at 540-720 min and for that of vacuum drying at 600-840 min. Three mathematical drying models for thin layer drying viz. Page, Lewis and Henderson-Pabis model were evaluated for both convective drying and vacuum drying. Statistical parameters such as the coefficient of determination (R2), root mean square error and reduced X² were used to fit the models. Page model was found to be satisfactory for both forced convective and vacuum drying of the nopal cladodes at 40 and 50°C respectively. Among these, two drying methods, forced convective drying method was found to be more suitable than the vacuum drying method for nopal cladodes on the basis of drying time and statistical parameters. [ABSTRACT FROM AUTHOR]

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Specific heat is a property of foods materials needed for analysis and design processes involving heat transfer. The specific heat of edible-wild mushrooms as affected by moisture content, temperature and mushroom variety was investigated in this paper. The ranges of moisture content and temperature studied in this paper were 0.05-0.80 kg water/kg sample and 10-90°C. The significant of the studying factors was analyzed and the regression analysis was then performed to determine the best model for predicting specific heat. The statistical analysis and software were performed and used for the judgment of the degree of accuracy of the fitted models. A linear function of specific heat with moisture content and temperature was proposed and model efficiency was evaluated statistically. The obtained model obviously outperformed the other conventional models and was found to be successful in much better specific heat prediction of mushroom varieties which will be very useful in practical use of mushrooms in industry. [ABSTRACT FROM AUTHOR]

The sorption isotherms of full-fat (FPKF), partially defatted (PDPKF), and totally defatted (TDPKF) pistachio kernel flour were performed in the range of water activity (αw) from 0.113 to 0.859 at 15°C, 25°C and 35°C, and the applicability of six mathematical models (Smith, Oswin, Henderson, GAB, Halsey and BET) in data prediction was evaluated. Sorption isotherms were type II, according to Brunauer's classification. Equilibrium moisture content (EMC) increased with an increase in αw at constant temperatures. The sorption isotherms of all three flour samples exhibited hysteresis. Significant differences were found among equilibrium data of FPKF, PDPKF and TDPKF samples. TDPKF showed higher hygroscopic characteristics than PDPKF, and PDPKF showed higher hygroscopic characteristics than FPKF at any temperature and αw studied. It was found that the Smith model was the most satisfactory one for representation of the sorption data of full fat sample, but for defatted samples, Halsey was the best model. The average monolayer moisture content (MMC) calculated by GAB model were 2.443-3.781 g/100 g (d.b.), 3.585-4.886 g/100 g (d.b.) and 5.093-6.918 g/100 g (d.b.) for FPKF, PDPKF and TDPKF, respectively. The isosteric sorption heat (Qst) calculated by means of Clausius-Clapeyron equation decreased with increasing moisture content. The Qst values were 44.76-74.67 kJ/mol, 44.75-99.44 kJ/mol and 44.80-133.28 kJ/mol for FPKF, PDPKF and TDPKF, respectively, in the range of moisture content of 2% to 41% (d.b.) at 25°C. [ABSTRACT FROM AUTHOR]

Compost compression processes, such as pelleting, increase bulk density, improve storability, reduce transportation costs and make easier materials handling using existing equipment for handling and storage of grains. It is important to prevent quality deterioration of pellets in long time storage. Therefore, it is necessary to reduce the moisture content of the pellets to less than 20% or less. In this research the drying kinetics of compost pellets were studied at air temperatures of 50°C, 60°C and 70°C, air velocities of 0.5, 1 and 1.5 m/s, particle sizes of 1.18 and 2 mm and pellet diameters of 6 and 8 mm. The maximum effective moisture diffusivity (1.78?10-9 m²/s) was obtained at air velocity of 1.5 m/s, air temperature of 70°C, particle size of 1.18 mm and pellet diameter of 8 mm. The activation energy of compost pellets varied from 25.88 to 57.4 kJ/mol under different conditions. The Page model was selected as the most suitable model, based on the statistical analysis. [ABSTRACT FROM AUTHOR]

Moringa oleifera leaves is known for its nutritive and medicinal relevance especially because almost every part of the plant can be used as medicine, food or other beneficial applications. In this study, drying characteristics of Moringa oleifera leaves were investigated using a Mechanical Convective Cabinet dryer at temperature of 45, 55, 65 and 75°C and at constant air velocity of 0.9 m/s. Thirteen (13) Mathematical models were fitted to the experimental data and the performance of these models was evaluated by comparing the coefficient of determination (R2), Root Mean Square Error (RSME) and reduced chi-square (χ2) between the observed and predicted moisture ratio for all conditions of drying. Results indicated that drying took place in the falling rate period as there was only a very short or no constant rate period in the drying curves. Also, there was a reduction in drying time and an increase in drying rate as the drying air temperature increased. Mathematical modeling of the drying characteristics showed that diffusion model gave the best for Moringa oleifera samples dried at 45 and 55°C while the Simplified Fick's (SFFD) diffusion was the best model for 65 and 75°C. The dried vegetables can be rehydrated and used in ready to eat foods. [ABSTRACT FROM AUTHOR]

A mathematical model is discussed in terms of moisture transfer during the drying process of Masson pine ( Pinus massoniana) lumber in industrial practice. The model was validated by comparing the simulated result of moisture distribution with experimental data. In the model, the wood drying process was divided into two phases. The first one dealt with processes above fiber saturation point (FSP), that was driven by capillary flux of free water and conductive flux of vapor, and the second one dealt with those of below FSP, which was driven by diffusive flux of bound water and vapor. Moisture content distribution (MCD) inside wood is simulated by solving a parabolic partial differential equation under Dirichlet boundary conditions. The moisture content profile (MCP) was asymmetrical in experiments, and the simulation result agreed well with the experiments. An easy empirical formulation was also proposed to calculate real wood permeability, as it showed general characteristics of liquid and vapor permeability. This permeability model is verified as the cause of asymmetrical MCP in this paper. [ABSTRACT FROM AUTHOR]

The pigment extraction process using annatto (Bixa orellana L.) seed produces a large amount of seed waste. Although most of these seeds are discarded, a number of studies report promising results with their use in animal feed. The good fiber content also suggests human nutrition applications, with possible incorporation in dietary foods. In the present study, annatto seeds derived from color extraction were dried, with and without the layer of oil left over from the process. Seeds were dried at 40, 50, 60 and 70 °C. Drying data were fitted to the Diffusion Approximation, Two Term, Midilli, Page and Thompson models. Drying was carried out up to a moisture content of approximately 5% wet basis. All the models studied exhibited adequate fit to the drying kinetics data of the annatto seeds, with coefficients of determination above 0.98 and root mean squared error (RMSE) below 1.0. Seeds with oil had longer drying times at 40 and 50 °C and shorter times at 60 and 70 °C. The coefficients of diffusion showed values between 2.67 x 10-11and 9.50 x 10-11m2 s-1 and between 2.7 x 10-11 and 6.21 x 10-11 m² s-1, while activation energies for liquid diffusions were 38.04 and 23.52 kJ mol-1, for residual seed drying with and without oil, respectively. [ABSTRACT FROM AUTHOR]

Knowledge of the equilibrium moisture content (EMC) is important for modelling and planning of drying and, to select the conditions for storage of biological products. Equations for modeling water sorption isotherms have special importance in many aspects of product preservation by dehydration. In this work, desorption and absorption isotherms for Melissa officinalis L. (Lemon Balm) were determined at four different temperatures (25, 40, 50 and 60°C) by using the method recommended by the project COST 90. This method is based on maintaining a known mass of sample to an atmosphere generated by the use of saturated saline solutions until achieving the balance. The saline solutions were prepared according to DIN 50008 for a range of relative humidity between 10 and 85%. Samples of 0.5 grams of whole leaves of Melissa officinalis L. variety Citronella were placed in perforated stainless steel bins, positioned inside of tightly sealed glass containers. The weight of the samples was registered until the samples achieved balance. Experimental data were fitted using the following mathematical models: BET, GAB, Halsey, Lagmuir, Oswin, Peleg, Henderson and Chung & Pfost. Using nonlinear regression, the experimental data was fitted to the considered models. The chi-square test and the coefficient of determination were used to evaluate the fit. Halsey's model was found to be the most suitable for describing the desorption curves at the temperatures of 25°C and 40°C and BET's model was most suitable for describing the data at the temperatures of 50°C and 60°C. [ABSTRACT FROM AUTHOR]

To describe water transport in a porous media, a mathematical model is usually used. Among the models available in the literature, empirical and diffusive ones can be cited. In this paper, Page and diffusion models are used to describe drying and soaking of chickpea. In addition, new empirical equation is proposed to describe the mentioned processes. According to the results, the two empirical models well describe drying and soaking, but the proposed one gives the best statistical indicators. The use of the diffusion model to describe the drying process makes it possible to determine the effective diffusivities (7.13 x 10-11, 10.39 x 10-11 and 13.78 x 10-11 m2 s-1 for the drying air at 40, 50 and 60 °C, respectively) and also the activation energy associated with the process (27.9 kJ mol-1). [ABSTRACT FROM AUTHOR]

Determination of physical properties of agricultural products, such as the potato, and their variations during long-term storage, is an important feature in achieving high product quality and consumer acceptance. Physical properties of potatoes (Agria, Satina, and Caesar cultivars), including surface area, volume, moisture content, weight, and three main diameters of tuber, were measured and then other properties, such as sphericity, roundness, geometric mean diameter, volume mean diameter, aspect ratio, effective diameter, and real density during storage time, were calculated. The measurements were done every 15 days for a period of 22 weeks and analyzed based on a completely randomized block design in ten replications. Significant differences were observed among three potato cultivars according to major diameter, shape characteristics, mass, volume, and surface area of tubers. In this relation, Satina was larger in size compared to the two other cultivars. However, the Agria cultivar was closer to a sphere in shape. Also, it was found that the surface area of each potato could be estimated based on its mass and volume by a power law equation with a high coefficient of determination. According to the results, real density of tubers increased as a function of storage time based on a polynomial equation with R2 = 0.99. During storage time, moisture content of tubers decreased according to a linear model and was probably the major rationale for decrease in tuber size. Density, size, and moisture content are the major physical characteristics of potato tubers, which change dramatically during long-term storage. Considerable differences in physical properties of different cultivars persuade researchers to carry out further studies on other popular potato cultivars. [ABSTRACT FROM AUTHOR]

Moisture desorption isotherms for yellow pitahaya fruits were studied at 15, 25, and 35 ° C using the gravimetric method for a 0.111-0.901 water activity range. Experimental values were adjusted by using the GAB, Henderson, Smith, Oswin y Chung y Fost models. The isosteric heat of adsorption (Qst) was determined using the Clausius-Clapeyron equation. The results showed that yellow pitahaya fruits exhibit type III adsorption isotherms and that the equilibrium moisture content (EMC) is temperature-dependent. For the same water activity value, the EMC decreased when temperature increased. The GAB model presented the best fit to the experimental values. The Qst dropped from 61.43 a 45.11 kJ/mol when the EMC increased from 0.08 to 0.56 g water/g dry matter, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, mass transfer during osmotic dehydration of cylindrical cut green beans in salt solution was investigated. The osmotic solution concentrations used were 10%, 20% and 26.5% (w/w) NaCl, osmotic solution temperatures used were 30 °C, 40 °C and 50 °C, the solution-to-green bean mass ratio was more than 20:1 (w/w) and the process duration varied from 0 to 6 hr. A two-parameter mathematical model developed by Azuara et al. (1992) was used for describing the mass transfer in osmotic dehydration of green bean samples and estimation of the final equilibrium moisture loss and solid gain. Effective radial diffusivity of moisture as well as solute was estimated using the analytical solution of Fick's second law of diffusion in the cylindrical coordinates. For above conditions of osmotic dehydration, moisture and salt effective diffusivities were found to be in the range of 1.776 × 10-10-2.707 × 10-10 m2/s and 1.126 × 10-10-1.667 × 10-10 m2/s, respectively. Moisture and solute distributions as a function of time and location in the radial direction were plotted by using the estimated equilibrium moisture and solute concentrations and also moisture and solute diffusivities. [ABSTRACT FROM AUTHOR]