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A pressure-based coupled heat and mass transfer model was used to simulate temperature and soil suction in a drying process within a clay soil column. Closed form functions were used for all parameters needed in the governing equations. Model predictions were compared with experimental data using the mean relative percentage deviation method. Thermocouples and mini-gypsum blocks were used to monitor the data collected hourly at different depths of the soil column. The model showed very high sensitivity to the proposed hydraulic conductivity function, while lower sensitivity was found for the proposed thermal conductivity function. This result highlights the importance of a proper hydraulic conductivity estimate while a rough estimate for thermal conductivity would have no significant adverse effect on the predicted values.

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Experimental infrared dryer was used to study the effect of rough rice temperature and air velocity on grain crack during infrared radiation and convection drying. Factorial experiment with Completely Randomize Block design was applied to the experiment at three temperature levels of 45, 60 and 75°C (equal to radiation intensities of 0.19, 0.39 and 0.58 W/cm2) and two inlet air velocity levels of 0.4 and 0.6 m/s. The result showed that the rough rice temperature (radiation intensity) and air velocity had significant effect on crack losses. Increasing the radiation intensity and decreasing air velocity caused to increase of crack percentage during drying of rough rice samples. The comparison of infrared and convectional drying method showed that grain cracks with infrared drying energy at 60 and 75 °C (0.39 and 0.58 W/cm2) were less than that with convection drying at the same temperatures. But it did not have a significant difference at 45 °C (0.19 W/cm2). The mathematical model relationship of grain crack percentage with rough rice temperature and air flow velocity was derived. Also the result show that the effect of rough rice temperature was more than air velocity on grain crack in infrared radiation drying.

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Saffron is one of the important agricultural products in Iran and has got importance in the Iranian agricultural export products. Iranian saffron dries under uncontrolled condition, as a result it’s got low quality. The aim of this study was to determine the effects of the three different ways of dehydration: Solar, Vacuum and Traditional on the qualitative characteristics of the saffron. The samples were picked randomly from the saffron farm on the Qayan city, The stigma,s separated from the flowers and the chemical tests were done on the fresh stigma,s and samples dried under controlled conditions(vacuum, solar) and then they were compared with the traditionally dried one,s. Quality attributes of dried samples were determined by chemical, microbial and sensory tests and compared with traditionally dried samples. Results of the chemical test indicated that, the amount of the crocine was high in solar, vacuum oven dried samples, in compare with traditionally dried samples (shade & R.T): the Safranal measured by HPLC method was the same in dried samples in three methods. The results of the sensory tests on color, aroma and texture showed that, the color in dried state was desirable in vacuum and solar dried than traditionally dried samples, color in liquid state, (vacuum dried, solar dried samples) had desirable quality. The microbial tests on samples, indicating that, the solar and vacuum dried samples were in standard levels but traditional dried samples were not in the standard level. In conclusion, if we consider the quality parameters (color, aroma, texture and microbial status of dried saffron), the quality of the solar and vacuum dried samples was high to campare with the traditionally dried samples. As a result the solar and vacuum methods of dehydration can be applicable for saffron preservation.

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  In order to increase the heat efficiency of solar driers a shelf type solar dryer with two collectors was designed and constructed in Agriculture Research Center of West Azarbaijan, and used to dry tomatoes slices. This experiment was conducted by complete randomized factorial experimental design in 2 factors and 4 replicates. The first factor was pretreatment in 3 levels, without pretreatment (control), dipping in boiling water for 15 second and dipping in 2/5% boiling brine for 10 seconds and second factor was drying method in two levels, open sun drying and shelf type solar dryer. The analysis of the results showed that average temperature of inside of the solar dryer in first and second years were 9/5  and 12 higher than the average ambient temperature respectively. The results also showed that in the first year the moisture contents of dried tomatoes produced using solar dryer was about 25% the lower than that produced by open sun drying, while in second year moisture contents were not significantly different. Also blanched slices in 2/5 % boiling brine had little damage, more rehydration ratio and better color in comparasion with other treatments. The percentage of damage and contamination of the sliced produced using solar dryer was reduced by 40% in comparison with. The samples dried in open air. Therefore according to the results obtained, it is recommended to blanch slices with 2/5 % boiling brine solution for 10 seconds to get a better results.  

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    Drying is one of the most important steps in raisin processing. During this step, initial moisture content is decreased up to 15 – 17 percent (d.b) for suitable storage. Achieving optimum drying conditions can affect the processing time and improvement of raisin quality. Temperature, air velocity and pretreatment are important factors in grape drying process and its quality. In this research, effect of the following conditions on time and drying rate of Black currant grape was studied: temperature at four levels of 50,60,70, and 80 ºC, air velocity at three levels of 1, 2 and 3 m/s, and four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydracids and no pretreatment. Diffusivity and activation energy of all treatments were determined. The results show that factors such as temperature, air velocity and pretreatment have significant effects on drying time and average drying rate. Pretreatment has a significant effect on drying process and decreases the time of drying up to 68 percent in some temperature levels. Also by increasing the temperature, drying time decreases up to 66.5 percent in some pretreatments. Increasing the hot air velocity decreases it about 8.3 percent.

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  Effect of variety, moisture and drying temperature on mechanical properties of soybean (failure force and energy, apparent modulus of elasticity and toughness) were studied. These properties were measured through quasi-static loading experiment by material testing machine. Factorial test with Randomized Block design was used to study the effect of drying parameters including final moisture content (3 levels: 10, 12 and 14% d.b.) and temperature (at 3 levels: 50, 60 and 70 ˚C) and varieties (Hill, Pershing and Gorgan3) on mechanical properties of soybean. The results showed that both drying factors (final moisture content and temperature) had significant effect on the force and energy failure. So that by increasing final moisture content from 10% to 14%, the failure force and energy increased from 47.5 N and 10 mJ to 82 N and 56 mJ, respectively. This different behavior of soybean in relation to other grains is due to a high amount of fat in soybean structure. Also by increasing drying temperature from 50˚C to 70˚C, the seed failure force was increased. Investigation of the effects of variety and moisture factors on toughness and apparent elasticity modulus showed that variety and moisture content had significant effect on three factors. Soybean elasticity modulus was 80.95 MPa at 10% moisture content, which by increasing moisture content to 14%, it decreased to 25.56 MPa. 

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Aim of pre-treatment drying of mulberry was to reduce the moisture content to a level that allows safe storage over an extended period. In this research after physical and chemical pretreatments, mulberry was dried industrially (cabin dryer). Non Enzymatic Browning was tested at 440 nm by spectroscopic method. Organoleptic tests were done by trained panelists. Hardness and cohesiveness of dried mulberries were measured by a texture analyzer. Statistical method was completely randomized design with 10 treatments and three replicates. The results showed that least intensity of brown color was in pretreatment of fruits with potassium meta bisulfate 0.5%  +calcium chloride %1. The highest water absorbance was in ethyl oleate 2%.   Panel tests showed highest score for overall acceptance in pretreatment of fruits with ethyl oleate 2% +potassium meta bisulfate 0.5%, highest score for texture with ethyl oleate 2% +calcium chloride %1, highest score for color with ethyl oleate 2% +potassium meta bisulfate 0.5%, highest score for odor with ethyl oleate 2% +citric acid %1 and also ethyl oleate 2% +ascorbic acid1%   and highest score for taste with ethyl oleate 2% +calcium chloride %1. Totally it is concluded that ethyl oleate 2%  , ethyl oleate 2% +citric acid %1, oleate 2% +ascorbic acid1%  , ethyl oleate 2% +potassium meta bisulfate 0.5% and oleate 2% +calcium chloride %1  are the best  pretreatment for drying of white mulberry.  

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Drying of foods is one of the most important preserving methods due to reduction of microorganisms’ activities which lead to longer shelf life. In spite of this, some changes may occur in dried food during storage. Our goal was to evaluate effect of pretreatment (blanching), variety and shelf life on quality of potato dried products (powder and cubes) to select proper usage duration and variety. Three cultivated potatoes of Golestan province of Iran (so-called Agria, Satina and Kenebek) were dried in two different dryer (hot air oven and microwave oven). Changes during shelf life were investigated by measuring ascorbic acid and reducing sugars content plus rehydration ratio (in 100ºC and 25). The factorial complete randomized design was selected as the statistical design. Results revealed that there was significant difference (p<0.05) between cubes and powders amount of components. Also water absorption of the products and ascorbic acid content, showed a significant (p<0.05) reduction during three months storage, so it was concluded that it was better to use dried products before this time. Also, products which were dried in hot air oven, had the highest percent of water absorption in 25 ºC water in the first month of storage but after  three months, it was changed to 100 ºC water. But the products which were dried in microwave oven had the highest percent of water absorption in 100 ºC during alls storage time. At last, Agria, because of its brilliant yellow color and low amount of reducing sugars, was the most accepted variety and proper usage duration was before three months storage.  

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A laboratory dryer used for a thin layer of  165 g Thompson orange slices with three thickness levels of 2, 4 and 6 mm, five different temperatures of  40, 50, 60, 70 and 80 °C and three air speed levels of 0.5, 1 and 2 m/s were employed to find the best dried and minimum energy consumption. This experiment was done in a complete randomized block design with the factorial treatments performed in three replicates. The energy consumption for drying thin slices of orange was calculated accordingly. The analysis of results showed that the lowest and highest drying energy consumption were 3.35 kWh (for 2 mm slice thickness and 40 °C)  and 15.2 kWh (for 6 mm slice thickness and 70 °C), respectively.

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       Drying is one of the most important steps in raisin processing. Achieving optimum drying conditions can affect the processing time and improvement of raisin quality. In this research, effect of two-temperature and pretreatments on time and drying rate of Black currant grape were studied. Drying was performed in two ways: In the first one, temperatures was constant at four levels of 50, 60, 70, and 80 ºC and in the second one sample were placed at two temperatures. In the latter, samples were placed at 80 ºC and when moisture content was reduced to 50%, temperature was set to 70, 60 and 50 ºC. Four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydracids and no pretreatment were performed. According to the results of the ANOVA, factors such as temperature, two-temperature and pretreatment have significant effects on drying time and average drying rate. Drying time of grape with two-temperature comparing with drying time of constant temperature was decreased up to 67% for some pretreatment. Maximum and minimum activation energy were determined 2893.9, 4538.8 kj/kg.

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Drying is one of the most important steps in grape processing. Drying causes some undesirable effects such as changing the quality of raisin by turning it to brown.  Achieving optimum drying conditions can improves quality of raisin. Temperature and pretreatment are important factors in establishing the quality of raisin. In this research the effect of pretreatment ( solutions of sodium Meta bisulphide 8 %, sodium Meta bisulphide 8 % and potassium carbonate 5%, ethyl oleat 2% and potassium carbonate 5%, ethyl oleat 2% and sodium Meta bisulphide 8 %, ethyl oleat 2% and sodium Meta bisulphide 8 % and potassium carbonate 5%)  and different drying methods( by sun, shade and air dryers at temperature of 50, 60, 70 and 80 ^◦C with the air flow rate of 1/5 m/s) was studied to understand the quality factors on colour. As some solutions contains sulphite, its remnant was studied too. The analysis of experimental data shown that the optimized drying conditions achieved by Ethyl oleat 2% and sodium Meta bisulphide 8 % and potassium carbonate 5%, sodium Meta bisulphide 8 %and drying temperature of 50,60^◦C.

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  In this study, Mazafati date samples were dried using a cabinet drier at five temperatures (50, 60, 70, 80 and 90 ˚C) and air flow rate of 1 m/s. Changes of total soluble solids, browning, pH, acidity and color parameters (L*, a* and b*) of date samples during drying were determined and compared. The results showed that total soluble solids, browning index and acidity increased and pH of date samples decreased. Moreover, L* and b* color parameters decreased and a* value increased. Overall, it was concluded that the moisture of Mazafati dates can be reduced by industrial drying. Furthermore, air temperatures of greater than 70˚C have negative effects on color of the date samples. Therefore, drying temperature of 70˚C was found to be the optimum condition for drying process of Mazafati date.  

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The objective of this study was to examine the effects of the fluidized-bed drying me-thod on the final quality of two varieties of Iranian rice, medium- and long grain. The re-sults were compared to that of paddy drying using a traditional method. Rough rice was treated in the fluidized bed drier at 140ºC for 2 minutes. Similar samples were dried for 8-10 hrs by the traditional method. Dried samples were dehusked and polished. Quality factors, including trade quality (head rice yield percent and whiteness), cooking quality (amylose content, gelatinization temperature, gel consistency, aroma and flavor) and nu-tritional quality (thiamine and lysine contents), were then measured for each sample. Fi-nally, the data was analyzed. Results show that paddy drying in a fluidized bed dryer would reduce the quality factors except for rice whiteness for which conventional drying is more acceptable. Therefore modification of fluidized-bed drying technique is recom-mended.

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The drying method, drying temperature and grain moisture content are parameters that affect on the milling waste (broken grains). At this study, effects of drying temperature with two levels (40 and 60 °C), grain moisture content with four levels (8, 10, 12, 14 %w.b.) and Guilan common paddy rice varieties with three levels (Hasani, Hashemi and Alikazemi) were investigated on the milling waste. Samples were milled by a laboratory rubber roll huller and laboratory abrasive whitener. The obtained results of data analyze showed that Hasani variety have minimum of waste mean (12.27%) with significant difference respect to Hashemi (15.32%) and Alikazemi (15.86%) varieties. With increasing drying temperature from 40 to 60 °C, hulling waste mean was increased significantly from 11.62% to 17.64%. With increasing of paddy grain moisture content from 8 to 14%w.b., hulling waste mean was decreased significantly from 20.83% to 8.64%. At among of tested varieties, the minimum (21.05%) and maximum (30.21%) means of husking waste obtained for Hashemi and Hasani varieties, respectively. Significant decreasing of whitening waste mean from 31.33% to 19.69%, obtained due to reduction of drying temperature from 60 °C to 40 °C. With increasing of paddy final moisture content from 8 to 14% w.b., whitening waste mean was decreased from 30.84% to 19.59%.

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  In this study, the impact of different drying conditions (4 levels of microwave power 130, 260, 380 and 450 watts and 4 absolute pressure levels 200, 400, 600 and 800 mbar) on drying rate, effective diffusion coefficient, activation energy, and energy consumption of a microwave–vacuum drier for drying the mushroom slices were analyzed. According to the findings, effective diffusion coefficient for mushroom varied between 3.21×10^-9 to 20.005×10^-9 m²/s. In addition, the activation energy based on an Arrhenius based exponential equation was very close to each other for three different methods. In terms of energy consumption, the minimum and maximum quantities were about 0.168 and 0.48 kWh, respectively.  

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  Honey as a medicinal and nutritional material contains about 60% reducing sugar and in liquid and natural state, presents significant handling problem in bulk production operation or consumption due to its viscosity and stickiness. Because of the convenience and ease of use, dried honey has special importance. In this study, feasibility of drying of commercial and noncommercial honeys, with or without water adding, by two methods of freeze drying and microwave drying was evaluated. Also the effect of drying method on chemical properties of the product was investigated. Results showed that not only drying method of honey is effective on quality of dried honey, but also minor differences in the raw honey can affect quality of the product.  Meanwhile, adding water to honey facilitates the drying process. According to the results, the amount of hydroxymethylfurfural (HMF) in noncommercial dried honey using microwave method is much higher than that in commercial honey samples which are dried in a similar way.    

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Drying is an important operational step in pistachio processing. There is a decrease in moisture content of pistachio nuts from 56-57% (d.b.) to 5-6% during the drying process. Drying conditions affect the quality of dried pistachio nuts, therefore, this calls for an accurate description of the drying trend in the process. In this study finite element formulation and solution of diffusive moisture transfer equation was presented to improve the drying simulation of nut as an axisymmetric body. The Fick’s diffusive model was solved with effective moisture diffusivity of 5.24×10-10 m2 s-1 for 55C and 7.01×10-10 m2 s-1 for 70C. For experimentation, thin layers of pistachio nut, ‘Ohadi’ variety, were dried at high drying air temperatures (55 and 70°C), three replications for each treatment, along with drying air velocity and relative humidity of 0.5 m s-1 and 20%, respectively. Good agreement was observed when the output of model was compared with the experimental data. Mean Relative Deviation (MRD) calculated for the model and the experimental data for the air temperatures 55 and 70C, were found to be 6.2% and 8.1%, respectively.

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This paper peresents a mathematical model for the thin layer drying of the Viliamz cultivar of soybean. The thin layer drying behaviour of soybean was experimentally investigated and the mathematical modelling performed by using thin layer drying models provided in the literature. Experiments were conducted at inlet drying air temperatures of 30, 40, 50, 60 and 70ºC and at a fixed drying air velocity of 1 m s-1. Thirteen different thin layer mathematical drying models were compared according to their r values, RMSE, 2 and EF by non-linear regression analysis. The effect of drying air temperature on the model constants and coefficients was predicted using multiple regression analysis. According to the results, the Midilli et al. model was found to be the best mathematical equation for modelling thin layer drying of soybean.

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Important parameters on apple drying process are investigated experimentally and modeled employing artificial neural network and neuro-Taguchi's method. Experimental results show that the apple drying curve stands in the falling rate period of drying. Temperature is the most important parameter that has a more pronounced effect on drying rate than the other two parameters i.e. air velocity and the thickness of apple slices. In order to model the drying process, a software was developed which uses the error back propagation algorithm for training. At first, the software was used to simulate the time-dependent variations of moisture content using neural network. Then in order to model the time derivation of moisture ratio in break point, the software was utilized in two ways. First, it was used with no use of any optimization method for modeling the process. In the other approach, the software in a hybrid fashion with Taguchi's method as an optimization method is utilized to correct weight matrix entries. The results demonstrate that the use of neuro-Taguchi's method can give some improvements over neural network accuracy as compared with conventional neural networks approach. By using neuro- Taguchi's method, error is reduced by about 46.4%.

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A thin layer solar drying method was compared with a traditional method (sun drying) of paddy drying, with their effects on quality characteristics of two varieties of Iranian rice (Kamphiroozi and Sazandegi) studied. Solar drying process was conducted in a passive, mixed mode type solar dryer at about 50ºC for 90 minutes. In sun drying method this process took 8-10 hours at a mean temperature of about 26ºC. Samples were milled and polished. Quality factors including trade quality (head rice yield percent and whiteness), cooking quality (amylose content, gelatinization temperature, gel consistency, aroma and flavor) as well as nutritional quality (thiamine and lysine contents) were evaluated. For a determination of head rice yield, the percentages of de-husked and broken kernels were determined by hand-sorting of broken kernels, the calculation being done through the pertaining formula. Gel consistency was determined according to the method of Cagampang et al. (the consistency of milled rice paste that has been gelatinized by being boiled in dilute alkali and then cooled to room temperature). Amylose content was determined through the simplified assay method of Juliano (setting standard curve by spectrophotometer and comparing the adsorption with the sample’s). Gelatinization temperature was estimated by the extent of alkali spreading and clearing of milled rice soaked in 1.7% KOH for 23 hours at room temperature. Organoleptic characteristics of cooked rice (iflavor, aroma) and apparent whiteness were judged by the taste panel using sensory evaluation method in triplicate. With respect to nutritional value, lysine amino acid was determined by using biological assay and applying Lactobacilllus delbrueckii while thiamine being measured through thiochrome fluorescence technique. The objective of this study was to examine the influence of solar drying process on the final quality of rice kernels and to compare the effects of this method with those in the traditional method of drying (natural sun drying). Results indicated that under the conditions prevailing in solar dryer, quality factors weren't affected except for whiteness of rice that too was better than that for sun dried samples. All other quality characteristics of the final product were acceptable in comparison with those in sun drying method.