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The influence of different drying temperatures and slice thicknesses on the drying kinetics of turmeric slices was studied to show how moisture is removed. The best model for predicting the drying kinetics was also determined. Turmeric slices (3 mm, 5 mm, and 7 mm) were dried at 40, 50, and 60 °C in a laboratory oven dryer. Four thin layer drying models (Newton, Henderson and Pabis, Logarithmic, and Page) were fitted to the experimental data and the selection was done based on the model with the highest correlation coefficient (R2), and lowest reduced chi-square (χ2), the sum of square error (SSE), and root mean square error (RMSE). Drying time varied between 420 min and 1140 min as the air temperature increased from 40 °C to 60 °C. The effective moisture diffusivity coefficient increased with increasing drying temperature and was found to be between 1.35×10-10 m2/s, and 5.00×10-10 m2/s, 3.00×10-10 m2/s and 10.91×10-10 m2/s, and 4.56×10-10 m2/s and 13.00×10-10 m2/s at 40 °C, 50 °C, and 60 °C, respectively. The values obtained for the activation energy for moisture diffusion were found to be 56.809, 56.060, and 45.561 kJ/mol for 3, 5, and 7 mm, respectively. The page model was found to best describe the oven drying of turmeric slices.

The influence of intermittent-microwave drying and hot-air drying on drying characteristics and rehydration properties of apple slices were compared. Microwave powers have crucially affected the drying rate, effective moisture diffusivity and drying time. As microwave power increased, the drying rate and effective moisture diffusivity increased while the drying time reduced. In intermittent-microwave drying, the effective moisture diffusivities were estimated between 4.47 × 10-9 and 2.54 × 10-8 m2 s-1. Longer drying time, slower drying rate and less effective moisture diffusivity were obtained from hot-air drying when compared to intermittent-microwave drying. Higher temperatures provided higher drying rate and effective moisture diffusivity. Effective moisture diffusivities of hot-air dried-apple slices were calculated in the range of 3.38 × 10-10–6.25 × 10-10 m2 s-1. Moreover, Page model gave the best fitting to intermittent-microwave drying curves, while hot-air drying curves were suitably described by Parabolic Model. On the other hand, the rehydration ratio of intermittent-microwave dried-apple slices was higher than hot-air dried-apple slices. Additionally, Peleg model was defined to be the best model predicting experimental rehydration data in both drying techniques. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

A comparative approach was carried out between artificial neural networks (ANNs) and response surface methodology (RSM) to optimize the drying parameters during infrared–con- vective drying of white mulberry. The drying experiments were performed at different air temperatures (40°C, 55°C, and 70°C), air velocities (0.4, 1, and 1.6 m/s), and three levels of infrared radiation power (500, 1000, and 1500 W). RSM focuses on the maximization of effective moisture diffusivity (D eff ) and minimi- zation of specific energy consumption (SEC) in the drying pro- cess. The optimized conditions were encountered for the air temperature of 70°C, the air velocity of 0.4 m/s, and the infrared power level of 1464.57 W. The optimum values of D eff and SEC were 1.77 × 10 −9 m 2 /s and 166.554 MJ/kg, respectively, with the desirability of 0.9670. Based on the statistical indices, the results showed that the feed and cascade-forward back-Propagation neural systems with application of Levenberg-Marquardt train- ing algorithm and topologies of 3–20-20-1 and 3–10-10-1 were the best neural models to predict D eff and SEC, respectively. This finding suggests that the ANN as an intelligent method with better performance compared to the RSM can be used to pre- dict the drying parameters of the infrared-convective drying of white mulberry fruit. info:eu-repo/semantics/publishedVersion

In this study, the effects of microwave power, vacuum degree and load weight on the moisture content of seedless white grapes (Vitis vinifera L.) during microwave vacuum drying were investigated. The result found that during microwave vacuum drying, the effective moisture diffusivity (Deff) of seedless white grapes ranged between 1.0232 × 10−9 and 4.6354 × 10−9 m2/s. The Deff values increased with the increase in the microwave power and the decrease in the load weight, the vacuum degree played a relatively minor role. The kinetics of moisture ratio and drying time were established, with the drying process following the Page model, as reflected by the fitting between model-predicted and measured data. The Page model was demonstrated to precisely describe and predict the moisture content variation in seedless white grapes during microwave vacuum drying.

In this study, the effect of different microwave and infrared power levels on drying kinetics of cherry tomatoes is investigated. Drying experiments are carried out with the power levels of 90, 180, 270 and 360 W (5.625, 11.250, 16.875 and 22.500 W/g as power density) in microwave studies and 74, 83 and 104 W (0.871, 0.976 and 1.224 W/g as power density) in infrared studies. The obtained experimental moisture ratios are fitted to seven different widely used thin-layer models and the results showed that Weibull and Aghbashlo et al. models best fit the data for microwave and infrared drying of cherry tomatoes. The effective moisture diffusivities for microwave and infrared drying studies are calculated between 5.46?10-8 and 4.24?10-7 m2/s and 7.33?10-9? ?8.24?10-9 m2/s, respectively. Additionally, microwave and infrared activation energies are found to be 9.4654 and 0.3162 kW/kg, respectively.

The Linden (Tilia platyphyllos Scop.) is a highly popular herbal plant due to its central nervous system properties. In this study, thin layer drying kinetics of linden leave samples were experimentally investigated in an infrared (IR) dryer. In order to select the appropriate model for predicting the drying kinetics of linden leaves, eleven thin layer semi theoretical, theoretical, and empirical models, widely used in describing the drying behavior of agricultural products, were fitted to the experimental data. Moreover, the color, projected area (PA), total phenolic content (TPC), and total flavonoid content (TFC) were investigated. The results showed that the drying time decreased from 50 min to 20 min. with increased IR temperature from 50–70 °C. Therewithal, the Midilli model gave the most suitable data for 50 °C, 60 °C. Moreover, Verma et al. and Diffusion approximation models showed good results for 70 °C. The lightness and greenness of the dried linden leaves were significantly changed compared with fresh samples. The PA of dried sample decreased similar to the drying time. In addition, the drying temperature effect on the effective diffusion diffusivity (Deff) and activation energy (Ea) were also computed. The Deff ranges from 4.13 × 10−12 to 5.89 × 10−12 and Ea coefficient was 16.339 kJ/mol. Considering these results, the Midilli et al. model is above the 50 °C, 60 °C, and the Verma et al. and Diffusion to 70 °C, for explaining the drying behavior of linden leaves under IR drying. Moreover, it can be said that the Page model can be used, if it is desired, to express the drying behaviors, partially with the help of a simple equation material by drying. TPC and TFC values were statistically < 0.001 higher in dried samples compared to fresh samples; however, no change has been recorded of TPC and TFC values at different temperatures (50 °C, 60 °C, 70 °C).

As an alternative to fish and beef, blue mussels (Mytilus edulis) can be consumed due to their high protein content. In this study, the drying kinetics and quality changes (cook loss, area shrinkage and colour change) in whole blue mussels were investigated with several infrared power levels between 88?146 W. Various thin-layer drying models were applied to the blue mussel and the Midilli et al., model best fits the experimental data (R2: 0.999150?0.999750, ?2: 0.000104?0.000030, RMSE: 0.008309?0.004797). The effective moisture diffusivity was determined to be between 4.24?10-9 and 1.10?10-8 m2/s. The activation energy was found to be 20.85 kW/kg. The cook loss and area shrinkage increased with increasing power level and drying time. Most cook loss (30%) and area shrinkage (30%) were obtained between 15-23 min and 8-20 min of drying time, respectively. The colour change was slightly affected by the change in infrared power level.

This paper presents thin‐layer drying of parchment coffee (Coffea arabica). Thin‐layer drying of parchment coffee was conducted under controlled temperatures (50°C, 60°C, and 70°C) and relative humidities (10%–30%). The temperature of the drying air was important for drying at a high temperature, which results in the rapid removal of moisture and reduced time for drying. Nine thin‐layer drying models (Newton, Page, Henderson and Pabis, logarithmic, two‐term, modified Henderson and Pabis, two‐term exponential, approximation diffusion, and modified‐Midilli) were fitted to the experimental data for parchment coffee. The drying parameters of parchment coffee were related to temperature and relative humidity. The best model was the modified‐Midilli model, which can be used to design the optimal dryer. The effective moisture diffusivity of parchment coffee drying was determined by minimizing the sum of squares of the deviations between the experimental data for the moisture content and the predicted values of thin‐layer drying. The effective moisture diffusivity as a function of the temperature at each relative humidity was expressed by the Arrhenius‐type equation.

Sierrathrissaleonensis (SL) is a low valued fish in Nigeria because of its small size and availability of fleshy alternatives. Therefore, an alternative utilization of SL is crucial. In this study, SL was used to produce fish cracker (SLC). The SLC, being an intermediate product was dried to achieve moisture stability. During drying process, the influence of drying factors (oven air velocity, sample thickness and oven temperature) on the effective moisture diffusivity (EMD) of SLC was investigated using response surface methodology (RSM) in Design Expert software. The uncertainty of the result and the sensitivity analyses of the drying factors to the variations of EMD were conducted using Monte Carlo simulation in oracle crystal ball (OCB) software. Results showed that fish cracker could be successfully developed with SL. The initial moisture content (d.b) of the SLC was 149.23%. Increment in oven drying temperature and oven air velocity increased the EMD of the SLC while increment in SLC sample thickness decreased the EMD of the SLC. The model developed had an R2 value of 0.9865. Model terms were significant at 5% confidence level. The theoretical optimum drying condition given by RSM showed that SLC should be processed at oven air velocity, SLC sample thickness and oven temperature of 3 m/s, 3 mm and 60°C, respectively to give an EMD of 2.75E-08. The validated SLC optimum drying condition was 2.69E-008. The certainty of achieving the experimental data range was 99.831%. The EMD of SLC drying process had +80.4%, -16.2% and +3.4% sensitivity to oven temperature, sample thickness and air velocity, respectively. These results are useful for the economic utilization of SL and will also assist in energy economics and product standardization during drying processing of SLC.

Onion slices were dried using two different drying techniques, convective and microwave drying. Convective drying treatments were carried out at different temperatures (50, 60 and 70 °C). Three different microwave output powers 328, 447 and 557 W were used in microwave drying. In convective drying, effective moisture diffusivity was estimated to be between 3.49 × 10−8 and 9.44 × 10−8 m2 s−1 within the temperature range studied. The effect of temperature on the diffusivity was described by the Arrhenius equation with an activation energy of 45.60 kJ mol−1. At increasing microwave power values, the effective moisture diffusivity values ranged from 2.59 × 10−7 and 5.08 × 10−8 m2 s−1. The activation energy for microwave drying of samples was calculated using an exponential expression based on Arrhenius equation. Among of the models proposed, Page’s model gave a better fit for all drying conditions used. © 2016, Springer-Verlag Berlin Heidelberg.

Kiwifruit slices were dried at four different air drying temperatures of 50, 55, 60 and 70ºC and at 2 m s-1 air velocity by using a cabinet dryer in this study. The drying, rehydration and colour characteristics were significantly influenced by pretreatment and drying temperature. The drying time decreased with the increase in drying temperature. The drying rate curves showed that the entire drying process took place in the falling rate period. Five well-known thin-layer models were evaluated for moisture ratios using nonlinear regression analysis. The results of regression analysis indicated that the Midilli & Kucuk model the best to describe the drying behaviour with the lowest c2 and RMSE values, and highest R2 value. The effective moisture diffusivity of the dried kiwifruit slices was calculated with Fick’s diffusion model, in which their values varied from 4.19×10–10 to 6.99×10-10 m2 s-1 over the mentioned temperature range. The dependence of effective diffusivity coefficient on temperature was expressed by an Arrhenius type equation. The calculated values of the activation energy of moisture diffusion were 10.37 and 19.08 kJ mol-1 for citric acid and control samples, respectively Kiwifruit slices were dried at four different air drying temperatures of 50, 55, 60 and 70ºC and at 2 m s-1 air velocity by using a cabinet dryer in this study. The drying, rehydration and colour characteristics were significantly influenced by pretreatment and drying temperature. The drying time decreased with the increase in drying temperature. The drying rate curves showed that the entire drying process took place in the falling rate period. Five well-known thin-layer models were evaluated for moisture ratios using nonlinear regression analysis. The results of regression analysis indicated that the Midilli & Kucuk model the best to describe the drying behaviour with the lowest c2 and RMSE values, and highest R2 value. The effective moisture diffusivity of the dried kiwifruit slices was calculated with Fick’s diffusion model, in which their values varied from 4.19×10–10 to 6.99×10-10 m2 s-1 over the mentioned temperature range. The dependence of effective diffusivity coefficient on temperature was expressed by an Arrhenius type equation. The calculated values of the activation energy of moisture diffusion were 10.37 and 19.08 kJ mol-1 for citric acid and control samples, respectively

The effect of the drying conditions on the retention quality for dried chicory roots (Cichorium intibyus L.) was investigated. Cubes of chicory roots were dried using hot air and vacuum dryers at 60 and 80 °C. Two different air velocities (0.2 and 0.7 m/s) were used in the hot air dryer, and two vacuum pressures (25 and 50 mmHg absolute) were set in the vacuum chamber. An exhaustive three dimensional mathematical model to describe mass transfer during drying of chicory roots of 1 cm of side was presented considering a polynomial functionality for the contraction kinetics. Experimental data obtained at laboratory scale were used to validate the proposed model showing good agreement between the experimental and estimated moisture profiles for both drying procedures. Moisture diffusivity was found to increase with the air drying temperature, velocity and vacuum pressure depending on the drying method. However, higher moisture diffusivity coefficients and lower activation energy values were obtained for the vacuum drying method. Samples dried using the vacuum drier at 60 °C and 25 mmHg presented better retention quality attributes, i.e., better rehydration, lower shrinkage and higher total phenolic content. The proposed mathematical model was able to satisfactorily predict the described behavior. Fil: Balzarini, Maria Florencia. Universidad Tecnológica Nacional. Facultad Regional Rosario; Argentina Fil: Reinheimer, Maria Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Tecnológica Nacional. Facultad Regional Rosario; Argentina Fil: Ciappini, Maria Cristina. Universidad Tecnológica Nacional. Facultad Regional Rosario; Argentina Fil: Scenna, Nicolas Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Tecnológica Nacional. Facultad Regional Rosario; Argentina

St. John's Wort (Hypericum perforatum L.) flowers with 25 g weight and 2.92 moisture on dry basis were dried in microwave oven using 1000, 850, 750, 650, 500, 350, 160 and 90 W microwave output powers and natural drying as a control, until the moisture fell down to 0.07 on dry basis. Drying processes were completed between 2 and 36 min depending on the microwave powers. The values measured were compared with the obtained data using Page's semi-empirical equations. By increasing the microwave output powers, the effective moisture diffusivity values ranged from 2.70 10-09m2s-1 to 1.54 10-10 m2 s-1. Energy consumption remained constant within the power range of 1000-650 W, whereas 500 and 90 W resulted in significant increase in energy consumption. Mean hypericin content values between natural drying and microwave drying with different microwave power varied between 0.241-0.280 %. Maximum hypericin content was observed natural drying (0.280 %), microwave drying of 850 W (0.278 %) and 750 W (0.277 %). The best quality in terms of hypericin content (0.278 %) was obtained in the drying period with 850 W. Microwave power of 850 W for 150 s which were produced the least energy consumption was only 0.06 kWh.

In this work, we tried to evaluate mass transfer during a combined infrared‐vacuum drying of kiwifruits. Infrared radiation power (200–300 W) and system pressure (5–15 kPa), as drying parameters, are evaluated on drying characteristics of kiwifruits. Both the infrared lamp power and vacuum pressure affected the drying time of kiwifruit slices. Nine different mathematical models were evaluated for moisture ratios using nonlinear regression analysis. The results of regression analysis indicated that the quadratic model is the best to describe the drying behavior with the lowest SE values and highest R value. Also, an increase in the power led to increase in the effective moisture diffusivity between 1.04 and 2.29 × 10−9 m2/s. A negative effect was observed on the ΔE with increasing in infrared power and with rising in infrared radiation power it was increased. Chroma values decreased during drying.

The accuracy of the knowledge of mass transfer parameters (effective moisture diffusivity, mass transfer Biot number and mass transfer coefficient) in the case of frying food, is essential and important for designing, modeling and process optimization. This study is undertaken to develop an approach for determining mass transfer parameters during frying of spherical rice cracker in sunflower oil at 150, 170 and 190°C. These parameters were evaluated from the plots of dimensionless concentration ratios against time of frying. Effective moisture diffusivity, mass transfer Biot number and mass transfer coefficient ranged between 1.24×10 −8 to 2.36×10 −8 m 2 /s, 1.96 to 2.34 and 5.51×10 −6 to 9.70×10 −6 m/s, respectively. Effective moisture diffusivity and mass transfer coefficient were found to increase with an increasing frying temperature, whereas mass transfer Biot number decreased. An Arrhenius-type relationship was found between effective diffusivity coefficient and frying temperature.

Drying of poplar wood (Populus Deltoides) particles was carried out at different drying conditions using a laboratory convective thin layer dryer. Drying curves were plotted and in order to analyze the drying behavior, the curves were fi tted to different semi-theoretical drying kinetics models. The effective moisture diffusivity was also determined from the integrated Fick’s second law equation and correlated with temperature using an Arrhenius- type model to calculate activation energy of diffusion. The results showed that Midilli et al. model was found to satisfactorily describe the drying characteristics of poplar wood particles dried at all temperatures and air flow velocities. In general, the drying rate increases with increasing air temperature and air fl ow velocity. A short constant drying rate period was observed and drying frequently took place at falling rate period in all cases. The effective moisture diffusivity of poplar wood particles increased from 1.01E-10 to 2.53E-10 m2·s-1 as the drying air temperature increased from 65 to 85 °C. The activation energy of diffusion for 1 m·s-1 and 1.5 m·s-1 air flow velocities were calculated as 27.8 kJ·mol-1 and 50.8 kJ·mol-1, respectively.

The effects of different drying temperatures on the drying kinetics of tomato slices were investigated using a cabinet-type dryer. The experimental drying data were fitted best to the to the Page and Modified Page models apart from other theoretical models to predict the drying kinetics. The effective moisture diffusivities varied from 1.015 x 10 -9 to 2.650 x 10 -9 m 2 s -1over the temperature range studied, and activation energy was 22.981 kJ mol -1. © Springer-Verlag 2011.

Extruding wheat semolina dough through a Teflon die allows to process pasta with a smooth and even surface, whereas bronze die can be used to obtain a product with a rough texture. Little is known about the impact of the die material on pasta properties other than surface characteristics. Knowledge of pasta properties would be relevant to better understand pasta digestibility. The aim of this work was to analyse the impact of the die material on engineering properties of dried pasta. Pasta were processed with fine semolina using a pasta extruder equipped with a 2.5 mm Teflon or bronze die. They were dried inside an environmental chamber under a controlled atmosphere at 40 °C or 80 °C for 20 hours. Pasta shrinkage, porosity and effective moisture diffusivity were measured. Scanning electron microscopy (SEM) was performed to characterize the external structure of pasta. Results showed that extrusion with a bronze die induces the production of more porous and less dense pasta, but does not have an impact on pasta shrinkage and volumetric percentage of water lost replaced by air during drying. Effective moisture diffusivity coefficients were higher for pasta extruded with a bronze die compared to a Teflon die for both drying temperatures studied, which indicates that the use of a bronze die could induce a diminution of the drying time. SEM observations at 50X and 500X clearly showed that pasta microstructure was affected by processing conditions. These results highlight the importance of food processing and their impact on the microstructure and characteristics of food matrices. Since pasta can be regarded as a good matrix for the incorporation of bioactive compounds beneficial to health and well-being, further studies are needed to better understand how processing would affect pasta digestibility and the release of bioactive compounds in terms of bioaccessibility into the gastro-intestinal tract.

The objective of this study was to investigate the drying characteristics and kinetics of red pepper and bitter leaf under the influence of different drying temperatures. The drying experiments were carried out at dry bulb temperature of 35, 45, 55 and 75oC, respectively in an oven dryer. The results showed that as drying temperature increased, drying rate also increased and the drying time decreased. It was observed that un-sliced red pepper and sliced bitter leaf would dry within 2.5-12 h and 1.67-7 h, respectively at temperature ranging from 75 to 35oC. The drying of red pepper and bitter leaf was both in the constant and falling rate period. Four semi-empirical mathematical drying models (Newton, Page, Henderson and Pabis, and Logarithmic models) were fitted to the experimental drying curves. The models were compared using the coefficient of determination (R^2) and the root mean square error (RMSE). The Page model has shown a better fit to the experimental drying data of red pepper and bitter leaf, respectively as relatively compared to other tested models. Moisture transport during drying was described by the application of Fick’s diffusion model and the effective moisture diffusivity was estimated. The value ranges from 15.69 to 84.79 × 10-9 m2/s and 0.294 to 1.263 × 10-9 m2/s for red pepper and bitter leaf, respectively. The Arrhenius-type relationship describes the temperature dependence of effective moisture diffusivity and was determined to be 37.11 kJ/mol and 32.86 kJ/mol for red pepper and bitter leaf, respectively. A correlation between the drying time and the heat transfer area was also developed.

The aim of this work was to study the effect of temperature and air velocity on the drying kinetics and quality attributes of apple (var. Granny Smith) slices during drying. Experiments were conducted at 40, 60 and 80 °C, as well as at air velocities of 0.5, 1.0 and 1.5 m s -1. Effective moisture diffusivity increased with temperature and air velocity, reaching a value of 15.30 × 10 -9 m 2 s -1 at maximum temperature and air velocity under study. The rehydration ratio changed with varying both air velocity and temperature indicating tissue damage due to processing. The colour difference, ¿E, showed the best results at 80 °C. The DPPH-radical scavenging activity at 40 °C and 0.5 m s -1 showed the highest antioxidant activity, closest to that of the fresh sample. Although ¿E decreased with temperature, antioxidant activity barely varied and even increased at high air velocities, revealing an antioxidant capacity of the browning products. The total phenolics decreased with temperature, but at high air velocity retardation of thermal degradation was observed. Firmness was also determined and explained using glass transition concept and microstructure analysis. © 2011 Elsevier Ltd. All rights reserved., The authors gratefully acknowledge the Research Department of Universidad de La Serena (DIULS), La Serena, Chile, for providing financial support for the publication of this research. In addition, we thank the microscopy service of Universidad Politecnica de Valencia, Spain; for assistance in relation to the Cryo-SEM micrographs and Instituto de Ciencia y Tecnologia de los Alimentos (ICYTAL) - Universidad Austral de Chile, for the DSC equipment.

Thin layer drying of Russian olive (Elaeagnusan gastifolial L.) fruit using a hot air dryer in order to calculate effective moisture diffusivity, activation energy and energy consumption has been evaluated in this article. The selected variables included three levels of air velocity of 0.5, 1 and 1.5 m/s and three air temperature levels of 50, 60 and 70°C. Increased air temperature increased effective moisture diffusivity but increase in air temperature had an inverse effect. Effective moisture diffusivity (Deff ) calculated for russian olive fruit in different temperatures and air velocities ranged between 5.56×10-11 to 3.18×10-10 (m2/s). The resulting values for activation energy had a minimum of 48.18 kJ/mol for 1.5 m/s air velocity up to a maximum of 63.83 kJ/mol for 0.5 m/s air velocity. The values for total and energy consumption in thin layer drying russian olive ranged between 16.34-75.04 (kW.h).

WOS: 000371930800015, The objective of the present study was to investigate microwave-assisted drying of Jerusalem artichoke tubers to determine the effects of the processing conditions. Drying time (DT) and effective moisture diffusivity (EMD) were determined to evaluate the drying process in terms of dehydration performance, whereas the rehydration ratio (RhR) was considered as a significant quality index. A pretreatment of soaking in a NaCl solution was applied before all trials. The output power of the microwave oven, slice thickness and NaCl concentration of the pretreatment solution were the three investigated parameters. The drying process was accelerated by altering the conditions while obtaining a higher quality product. For optimization of the drying process, response surface methodology (RSM) and genetic algorithms (GA) were used. Model adequacy was evaluated for each corresponding mathematical expression developed for interested responses by RSM. The residual of the model obtained by GA was compared to that of the RSM model. The GA was successful in high-performance prediction and produced results similar to those of RSM. The analysis and results of the present study show that both RSM and GA models can be used in cohesion to gain insight into the bioprocessing system.