Introduction: Today, drying of agricultural products is a developed method that removes part of the moisture leads to physicochemical stability of the product, also, produces different products with new qualitative properties and different nutritional and economical value. Moisture diffusivity coefficient is the most crucial property in drying calculations. Materials and Methods: In this study, drying kinetics modeling of Balangu seed gum in an infrared dryer was investigated. The effect of samples distance from the radiation lamp in three levels of 5, 7. 5 and 10 cm and the effect of gum height in the container in three levels of 0. 5, 1. 0 and 1. 5 cm on the mass transfer rate and effective moisture diffusivity coefficient during the dry process of Balangu seed gum was investigated. Standard models (Wang and Singh, Henderson and Pabis, Approximation of diffusion, Page, Modified Page, Newton, Midilli, and Logarithmic) were fitted to experimental data to study the drying kinetics and was analyzed. Results: The results showed that samples distance from the radiation lamp and samples thickness had significant effect on the mass transfer rate during drying of gum. By increasing samples distance from the heat source from 5 to 7. 5 cm and from 7. 5 to 10 cm, the drying time of Balangu seed gum increased by 21. 49% and 15. 20%, respectively. The effect of sample distance from infrared heat lamp and sample thickness on changes in effective moisture diffusivity coefficient of Balangu seed gum was investigated and results showed that this coefficient values were increased with decreasing in distance and increasing samples thickness. By reducing sample distance from the lamp from 10 to 5 cm, it was observed that the effective moisture diffusivity coefficient increased from 4. 82×10-9 m2s-1 to 7. 05×10-9 m2s-1. Conclusion: In drying process modeling of Balangu seed gum, the Page model with the highest coefficient of determination and the lowest error, had closer results to the experimental data than the other models.

Thin layer drying behavior of sweet lemon slice was experimentally investigated in a convective type dryer and the mathematical modeling performed, using thin layer drying models given in literature. Drying experiments were conducted at inlet drying air temperatures of 40, 50, 60, 70 and 80oC; two slice thicknesses of 3 and 6 mm, and, at one drying air velocity of 0.5 m/s with three replications in each treatment. Page model was employed (according to their coefficients of correlation) to estimate the drying curves. The effects of drying air temperature on the model constants and coefficients were evaluated through a non-linear regression technique. The accuracy of the model was estimated according to three statistical parameters of: coefficient of determination (R2), Chi-square (X2) and Root Mean Square Error (RMSE). Results indicated that Page model could satisfactorily describe the drying curve of sweet lemon slices with R2=0.99812, (X2)=0.0000518 and RMSE=0.003912 for a thickness of 3 mm while R2=0.997776, (X2)=0.0000715 and RMSE=0.0082232 for a thickness of 6 mm. Moisture transfer from the slices was described by applying Fick's diffusion model. The effective diffusivity coefficient values changed from 8.04x10-9 to 7.63x10-8 m2/s for the range of temperatures considered. An Arrhenius relation with an activation energy value of 28.53 kJ/mol and the diffusivity constant of 5.01x 10-4 m2/s for a thickness of 3 mm, while 39.46 kJ/mol along with a diffusivity constant of 9.37x10-4 m2/s for a slice thickness of 6 mm, were obtained, indicating the effect of drying air temperature and slice thickness on the diffusivity parameter.

This research aimed to investigate the process of pistachios solar drying in two different conditions of the designed dryer (recycle and without recycle modes). As well, in this study, the drying kinetics curves of pistachio were drawn and its dewatering behavior was monitored by empirical models. Furthermore, the mass transfer rate (MTR) of the examined product during drying in two noted modes was determined by Fick’, s 2 nd law. Maximum, minimum, and average values of collector output air temperature were recorded 54. 20, 32. 30, and 42. 99 o C & 47. 10, 30. 70, and 40. 03 o C in air recycle and without air recycle modes, respectively. The results dedicated that, 18. 75 % saving in drying time was obtained for air recycle mode compared with without air recycle mode. Also, the obtained data revealed that the drying rate of pistachio nut under recycle mode was higher than that of pistachio nut under without recycle mode, especially during the first hours of drying. Moreover, the empirical modeling showed that the Parabolic and Diamante et al. models were found to be the most suitable for describing drying curve of the thin layer solar drying process of whole pistachio nut under recycle and without recycle modes, respectively. In addition, the highest value of effective moisture diffusivity was observed in solar dried pistachio nut under air recycle mode with the Deff value of 2. 26×10-6 m /h 2 (R =0. 9265).

In this research drying kinetics, moisture diffusivity and determination of most appropriate mathematical modeling and activation energy of Mazafati dates species were studied under a cabinet solar dryer. Drying experiments were carried out at three air temperatures of 50, 65, and 80oC and three air velocities of 1.0, 1.5, and 2.0 m/s. Effect of temperature and air velocity evaluated on drying time and shrinkage by using a completely randomized statistical design. Results showed that the effects of temperature and air velocity are significant on drying time. The average increase of temperature from 50oC to 80oC caused the drying time to decrease by 70.77%. For determination of most appropriate model, the highest value of R2 and the lowest values of c2 and RMSE were used. For mathematical modeling, eight empirical models were fitted on experimental data and the best model was selected. The result of regression analysis showed that Page model has the best fitting with data. Moreover, the lowest and highest value of moisture diffusivity were obtained as 4.309×10-10 and 0.0188×10-9 m2/s at temperatures of 80oC and 50oC, respectively. Also the values of activation energy in the drying of Mazafati dates species were found between 31.22 to 42.27 kJ/mol.

The aim of this study is to report, its basil leaves effective coefficient moisture diffusivity determined and activation energy. The thin-layer drying experiments were carried out under five temperatures of 40, 50, 60, 70 and 80oC, three air velocity 1.5, 2 and m/s and three level of relative humidity 20, 40 and 60%. Moisture transfer from basil leaves was described by applying the Fick’s diffusion model. The effective diffusivity values changed from 1.05009×10-11 to 2.2491×10-10 m2/s for the range of temperatures considered. An Arrhenius relation with an activation energy value of 44.04 to 60kJ/mol and the diffusivity constant value of 1.29618391×10-7 to 1.31327786×10-4 m2/s were obtained which shows the effect of the drying temperature, air velocity and relative humidity on the diffusivity.

Knowledge of desorption kinetics is essential to predict the behavior of the material during drying process and to design dryer equipment. The main objective of this study is to obtain the effective diffusivity coefficient and activation energy of shelled pistachio. Another goal is to find drying kinetics of shelled pistachio in fluidized bed dryer and so thin-layer characteristics of shelled pistachios were determined experimentally as a function of temperature and air velocity. Accordingly, 6 mathematical models (Two term model, Exponential model, Logarithmic model, Page model, Modified page model and Henderson & Pabis model) for describing the thin-layer drying behavior of shelled pistachios were investigated. Tests were conducted using four air temperature (25, 30, 45 and 60 C), and three air velocities (6, 8 & 10m/s). Out of the 6 models considered, the two term model was considered to be the most suitable for describing the drying behavior of the shelled pistachios. Also, for high air temperature and velocity, Henderson-Pabis model proved to be suitable. Results showed that air velocity and operating temperature enhanced the kinetics of drying of shelled pistachio and the drying air temperature had a great effect on the drying kinetics. By using of Fick’s second Law the effective diffusivity coefficient and activation energy of pistachio was determined.

IntroductionSour cherries (Prunus cerasus L.) are relatively diverse and broadly distributed around the world, being found in Asia, Europe, and North America. Sour cherries have unique anthocyanin content, and rich in phenolic compounds. The fruits are generally used for processing purposes, such as for production juice and jam. The fruits of sour cherries can also be frozen and dried. One of the best methods for the preservation of agricultural product is drying, which involves removing water from the manufactured goods. Dried sour cherries have a long shelf life and therefore may be a fine alternative to fresh fruit all year round. There are no reports on the effect of microwave pretreatment on the hot air drying kinetics of sour cherries in the literature. Hence, the purpose of this study was to estimate the impacts of microwave pretreatment on the total phenolics, drying time, mass transfer kinetic, effective moisture diffusivity, total color difference index, shrinkage and rehydration of sour cherry. In addition, the moisture ratio changes of sour cherry during drying were modeled. Material and MethodsSour cherries were purchased from the market at Bahar, Hamedan Province, Iran. The average diameter of fresh sour cherries was 1.6 cm. In this study, the water content of fresh and dried sour cherries was calculated using an oven at 103°C for 5 h (Shimaz, Iran). In this research, the effect of microwave time on the drying time, effective moisture diffusivity coefficient and rehydration of sour cherries was investigated and drying kinetics were modeled. To apply the microwave pretreatment on the sour cherries, a microwave oven (Gplus, Model; GMW-M425S.MIS00, Goldiran Industries Co., Iran) was used under atmospheric pressure. In this work, the influence of the microwave pretreatment time at five levels of 0, 30, 60, 90, and 120 s (power=220W) on the cherries was examined. After taking out the treated sour cherries from microwave device, the samples were placed in the hot-air dryer (70°C) as a thin layers. The dehydration kinetics of sour cherries were explained using 7 simplified drying equations. Fick's second law of diffusion using spherical coordinates was used to calculate the moisture diffusivity of sour cherries at various hot-air drying conditions. The rehydration test was conducted with a water bath (R.J42, Pars Azma Co., Iran). Dried sour cherries were weighed and immersed for 30 min in distilled water in a 250 ml glass beaker at 50°C. Results and DiscussionThe results showed that microwave treatment led to an increase in moisture removal rate from the sour cherries, an increase in the effective moisture diffusivity coefficient, and, consequently, a decrease in drying time. By increasing the microwave time from 0 to 12 s, the average drying time of sour cherries in the hot-air dryer was decreased from 370 min to 250 min (p<0.05). The average effective moisture diffusivity coefficient calculated for the samples placed in the hot-air dryer was 4.25×10-10 m2/s. Increasing the microwave time from 0 to 120 s increased the average effective moisture diffusivity coefficient by 85%. The maximum amount of phenolic was related to the sample treated with microwave for 90 seconds. Microwave treatment time had no significant effect on the rehydration of dried sour cherries. ConclusionKinetic modeling of weight changes of sour cherries during drying was carried out using models in the sources, followed the Page model was selected as the best model to predict moisture ratio changes under the selected experimental conditions. The mean values of sum of squares due to error, root mean square error, and r for all samples ranged from 0.001 to 0.007, 0.005 to 0.017, and 0.997 to 0.999, respectively. Generally, 120 s pre-treatment by microwave is the best condition for drying sour cherries.

At this study drying kinetic of kumquat fruit slabs was evaluated at 60, 70 and 80oC temperature and 3, 5, and 7 millimeter thickness. Amount of effective moisture diffusivity (Deff) measured using Fic's second low and drying process fitted by ten difference mathematical models. Results showed that Deff increases with drying temperature and thickness of slabs. The best model with the highest of fitting mid maximum of R2 and minimum of Root mean squares error (RMSE), Mean relative percent deviation (MRPD) and reduced chi - square(c2) was midlli equation.