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The effect of drying methods on drying characteristic, energy consumption and color has been investigated for nectarine in this study. Sun, hot air, microwave and infrared drying techniques were applied as drying methods. The drying temperature was determined as 50 °C for hot air drying of nectarine, as the applied powers were 90W and 83W for microwave and infrared dryings, respectively. The results obtained from the experiments indicate that the microwave drying method is the most effective method for drying of nectarine. The higher "L" value and lower "-a/b" ratio values were obtained in hot-air dried nectarine slices. The results have been modelled with six different models in the literature to determine the drying kinetics for nectarine. Comparing the high R², low RMSE and χ2 values for all drying methods; it is presented that "Midilli et al." model is the most convenient model for drying of nectarine. [ABSTRACT FROM AUTHOR]

The effects of pretreatments such as citric acid and hot water blanching and air temperature on drying and rehydration characteristics of red kidney bean seeds were investigated. Drying experiments were carried out at four different drying air temperatures of 50°C, 60°C, 70°C, and 80°C. It was observed that drying and rehydration characteristics of bean seeds were greatly influenced by air temperatures and pretreatments. Four commonly used mathematical models were evaluated to predict the drying kinetics of bean seeds. The Weibull model described the drying behaviour of bean seeds at all temperatures better than the other models. The effective moisture diffusivities (Deff) of bean seeds were determined using Fick's law of diffusion. The values ofDeffwere between 1.25 × 10−9and 3.58 × 10−9 m2/s. Activation energy was estimated by an Arrhenius-type equation and was determined as 24.62, 21.06, and 20.36 kJ/mol for citric acid, blanch, and control samples, respectively. [ABSTRACT FROM PUBLISHER]

The effect of different infrared power levels on drying kinetics of red kidney bean seeds was investigated. The bean seeds were dried at 83, 125, 167 and 209 W infrared power levels and constant seed diameter is 1.14 cm. It is observed that drying characteristics of bean seeds were greatly influenced by infrared power. The drying data were fitted with 10 thin-layer drying models available in the literature. According to the results, Midilli et al. model is superior to the other models for explaining the drying kinetics of bean seeds. Effective moisture diffusivity was calculated and was between 1.75 × 10-9 and 1.02 × 10-8 m²/s within the studied infrared power level range. Activation energy was estimated by a modified Arrhenius-type equation and found to be 9.54 kW/kg. [ABSTRACT FROM AUTHOR]

The effect of pretreatments on drying characteristics of quince slices was investigated in a cabinet dryer. The experiments were conducted on quince slices with a thickness of 5 mm at 50°C, 57°C, 64°C, and 71°C with an air velocity of 2.0 m/s. Prior to drying, quince slices were pretreated with citric acid solution or blanched in hot water. Also, the untreated samples were dried as control. The shortest drying time was obtained with quince pretreated with citric acid solution. It was also observed that the rehydration ratio was higher in blanched slices than others. The drying data for the moisture ratio over time was fitted to three thin-layer models with the best performances coming from the Page model. The values of effective moisture diffusivity were found to range between 6.97 × 10−11and 2.38 × 10−10 m2/s, with activation energy of 29.08–43.01 kJ/mol for quince slices. [ABSTRACT FROM PUBLISHER]

Drying of pomegranate by-products that are formed at the instance of pomegranate juice processing was studied at 50, 60, 70 and 80 C while air velocity was 2 m/s. The results obtained show that moisture content of the by-product decreases with time and temperature. The drying process takes place mainly in the falling rate period. Several thin-layer drying models were selected to describe experimental drying kinetics data. The models were compared based on their coefficients of determination ( R2), reduced chi-square ( χ2) and root mean square error ( RMSE) between experimental and predicted moisture ratios. Consequently, the Midilli et al. model was selected as the best mathematical model for describing the drying kinetics of the pomegranate by-products. The effective moisture diffusivity of pomegranate by-product varied from 1.22 × 10−10 m2/s to 4.29 × 10−10 m2/s. The activation energy was calculated as 39.66 kJ/mol using Arrhenius-type equation. Practical Applications Pomegranate is an important commercial fruit crop that is extensively cultivated all over the world in tropical, subtropical and temperate zones. It is mainly consumed as a raw staple food and used to mix in jams, jellies, teas, beverages, and concentrated in syrups and liqueurs. The process of pomegranate juice production remains large quantities of pomegranate by-products such as peels and seeds. The by-products due to high initial moisture content are very sensitive to microbial spoilage. Drying is one of the preservation methods applied to agricultural products. The basic objective in drying agricultural products is the removal of water in the solids up to a certain level, at which microbial spoilage and deterioration chemical reaction are greatly minimized. Besides, knowledge of drying characteristics is important in the design, simulation and optimization of drying process. [ABSTRACT FROM AUTHOR]

The freeze drying is a suitable dehydration process for saffron that contains heat-sensitive volatile and aroma-yielding compounds such as crocin (act as a coloring agent), picrocrocin (responsible for the taste) and safranal (volatile oil that gives characteristic odor and aroma). The heat-sensitive volatile and aroma-yielding compounds of saffron can be more preserved using freeze drying in comparison with other conventional drying methods. In this study the freeze-drying characteristics of saffron was determined experimentally. The drying kinetics data were fitted to 10 different empirical diffusion drying models from literature to find the best model that represents the weight loss of saffron during the freeze drying. Among the models tested in this study, the Page model was found to be the best model in representing the drying kinetics of saffron during the freeze drying. Effective diffusivity found as 1.62 × 10−11 m2/s. Practical Applications Saffron, which has been intensively used for flavoring and coloring foods, dying textile and medical purposes since ancient times, is the most precious and expensive agricultural product in the world. Freeze drying, which is both slow and expensive, is the method of separation for high market value products. It has been shown that freeze drying can be used for dehydration of saffron with minimum safranal (main aroma component) and crocin (coloring agent) loss. High cost of freeze drying of saffron can be compensated by minimum loss of safranal and crocin contents in the final product. It is crucial to know the drying kinetics of saffron to determine the drying time under certain conditions. In this work, the freeze-drying kinetics of saffron were studied and the best empirical model that represents the weight loss of saffron during the freeze drying and effective diffusivity were determined. [ABSTRACT FROM AUTHOR]

The effect of different infrared power levels on the drying kinetics of button mushrooms was investigated. Mushroom slices were dried at infrared power levels of 83, 125, 167, and 209 W. The power level affected the drying and rehydration characteristics of mushroom slices. Drying time was reduced from 300 min to 40 min as the infrared power level increased from 83 to 209W. Mathematical models frequently used to represent drying of agricultural products were fitted to experimental data of mushroom drying. The parabolic model was the best for representation of mushroom drying. Effective moisture diffusivity varied from 3.81×10 to 4.20×10 m/s over the infrared power levels used. The activation energy was estimated using a modified Arrhenius-type equation and calculated to be 7.55 kW/kg. [ABSTRACT FROM AUTHOR]

Drying characteristics of broccoli was experimentally studied in cabinet-type convective dryer. Experiments were conducted using constant air velocity of 2 m/s and air temperature of 60 ℃. Drying rate increased with increasing blanching temperature and thus reduced the drying time. The experimental drying data were used to fit twelve drying models and drying rate constants and coefficients of the models were determined by non-linear regression analysis. Estimations by the Midilli et al. model were in good agreement with the experimental data obtained. Fick’s second law was used to calculate the effective moisture diffusivity, which varied from 1.987 to 3.577 × 10-8 m2/s for the given blanching temperature range. The rehydration ratio was observed to increase with increasing blanching temperature. [ABSTRACT FROM AUTHOR]

In this work, bay laurel leaves were dried using pilot-scale, cabinet-type, convective dryer. Drying experiments were conducted using constant air velocity of 2 m/s and air temperatures of 50, 60 and 70 C. Drying rate increased with increase in air temperature and thus reduced the drying time. The experimental drying data were applied to 14 thin-layer drying models. Nonlinear regression analysis was performed to relate the parameters of the model with the drying conditions. The performance of these models is evaluated by comparing R2, χ2 and RMSE between the observed and predicted moisture ratios. Among all the models, Midilli et al.'s model was found to be the best for explaining the drying characteristics of bay laurel leaves. The effective moisture diffusivity ranged from 9.38 × 10−12 to 2.07 × 10−11 m2/s over this temperature range studied, with activation energy of 36.48 k J/mol for bay laurel leaves. Practical Applications Drying is the most important process to preserve agricultural products, because it has a great effect on the quality of the dried products. The objective in drying foods is the reduction of the moisture content to a level that allows safe storage over an extended period. Bay laurel plants are known for cosmetic industry, food and medicinal purposes. This study concerns the investigation of the drying characteristics and presents a mathematical model for thin-layer drying of bay laurel leaves. [ABSTRACT FROM AUTHOR]

The effect of different infrared power levels on the drying kinetics and rehydration capacity of tomato slices was investigated. The tomatoes were cut into eighths and dried at different infrared power levels. It was observed that the power levels affected the drying time and rehydration capacity. Drying time was reduced from 450 to 240 min as the infrared power level increased from 125 to 188 W. The experimental data obtained from drying study were fit with nine mathematical models to evaluate the drying kinetics of tomato slices. The fit quality of the proposed models was evaluated using the determination of coefficient, mean relative percent error, reduced chi-square and root mean square error. Among the nine drying models, the model of Midilli et al. showed the best fit of drying kinetics of tomato slices. Effective moisture diffusivity varied from 2.66 to 5.17 × 10−9 m2/s and was significantly influenced by infrared power. Practical Application Tomato is an important commercial vegetable, having the highest production figures of all the vegetables in the world. It is used to a great extent in the fresh state and in some processes as juice, puree, sauces, dried and canned varieties. Tomatoes are highly perishable because of their high moisture content; therefore, they need to be dried. Infrared drying has appeared as one of the potential alternatives to the traditional drying methods in obtaining high-quality dried products. Infrared drying characteristics of tomato slices were studied in this work. The effect of infrared power level on the drying kinetics and rehydration capacity of tomato slices was determined. [ABSTRACT FROM AUTHOR]

ABSTRACT The water absorption characteristics of dried green bell peppers were studied at hydration temperatures at 25, 50 and 75C. Prior to drying at 65C, green bell peppers were pretreated with ethyl oleate (AEEO) and citric acid (CITRIC) solutions. Initial rehydration rates increased with rehydration temperature for all samples and were highest for the AEEO pretreated samples. At all rehydration temperatures, the equilibrium moisture contents were highest for the pretreated with AEEO solution. The moisture diffusivity (D) was determined by using Fick's second law. The values of D varied from 16.8 to 32 × 10−8, 9.16 to 16.7 × 10−8 and 9.73 to 19.9 × 10−8 m2/s for AEEO, CITRIC and CONTROL samples, respectively, over the temperature range investigated. PRACTICAL APPLICATIONS The rehydration characteristics, which indicate the physical and chemical changes during drying process of a dried product, are used as a quality index. Therefore, drying conditions should be optimized to obtain the dried product with good rehydration characteristics. In the present manuscript, studies were conducted to probe the kinetics of rehydration of dried green bell peppers. The effect of pretreatment of green bell pepper with chemicals (ethyl oleate and citric acid) and rehydration temperature on the rehydration kinetics was studied. Important rehydration kinetic parameters were evaluated, which helped in successful modeling of the kinetics. [ABSTRACT FROM AUTHOR]

Drying characteristics of purslane was experimentally studied in a cabinet dryer. The experimental drying data were fitted best to Modified Henderson and Pabis and Midilli et al. models apart from other models to predict the drying kinetics. The effective moisture diffusivity varied from 1.12 × 10 to 3.60 × 10 m/s over the temperature range studied and activation energy was 53.65 kJ/mol. [ABSTRACT FROM AUTHOR]

The effect of different infrared power levels (104, 125, 146 and 167 W) on drying kinetics and rehydration ratio of sweet potato slices was investigated. It was observed that the power levels affected the drying time and rehydration ratio. The increase in infrared power level decreased the drying time. The experimental data obtained from drying study were fitted with Newton, Henderson and Pabis and Logarithmic models to evaluate the drying kinetics of the sweet potato slices. The fit quality of the proposed models was evaluated by using the determination of coefficient ( R), mean relative percent error ( P), reduced chi-square ( χ) and root means square error ( RMSE). Among the three drying models, the Logarithmic model gave a better fit over the other two models. Effective diffusivity varied from 1.31 × 10 to 3.66 × 10 m/s and was significantly influenced by infrared power. [ABSTRACT FROM AUTHOR]

The thin-layer drying characteristics of pomegranate arils were investigated at the temperature of 55, 65 and 75°C, and the thin-layer drying models were used to fit the drying data. The increase in drying air temperature resulted in a decrease in drying time. Five different thin-layer drying models were used to predict the drying characteristics. The Midilli et al. model showed a better fit to experimental drying data as compared to other models. Effective moisture diffusivities were calculated based on the diffusion equation for a spherical shape using Fick's second law, and varied from 9.373 × 10 to 3.429 × 10 m/s over the temperature range. Moisture diffusivity values increased as air temperature was increased. The dependence of moisture diffusivity on temperature was described by an Arrhenius-type equation. The activation energies of control and pre-treated samples were determined to be 49.7 and 40.1 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

The effect of temperature on the drying kinetics of pear slices was investigated. The drying process was carried out at temperatures of 55, 65, and 75°C. Drying time decreased considerably with increased air temperature. Seven mathematical models available in the literature were tested with the drying patterns. The Wang and Singh, and Midilli et al. models were given the best results in describing drying of pear slices. Effective moisture diffusivity increased with increasing air temperature, and varied from 0.85 to 2.18×10 m/s over the temperature range investigated, with activation energy equal to 44.78 kJ/mol. [ABSTRACT FROM AUTHOR]

Effect of different infrared (IR) power levels on drying kinetics of pomegranate seeds was investigated. The pomegranate seeds were dried at 83, 104, 125, and 146 W IR power levels. It was observed that the power levels affected the drying rate and time. Drying time reduced from 150 to 60 min as the IR power level increased from 83 to 146 W. The experimental data obtained from drying study were fitted with 10 mathematical models to evaluate the drying kinetics of the pomegranate seeds. The Page, Midilli et al., and Weibull models are given better prediction than the other models and satisfactorily described drying kinetics of pomegranate seeds. Effective diffusivity varied from 1.96 to 6.29×10 m/s and was significantly influenced by IR power. [ABSTRACT FROM AUTHOR]