جستجوی مقالات مرتبط با کلیدواژه « drying » در نشریات گروه « صنایع غذایی »

Sour 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.

Sour 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.

The 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.

Kinetic 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.

Effect of osmosis dehydration, ultrasonic and edible coating as the pretreatment before drying has been studied in order to improve the flavor of the product, reduce thermal damages, decrease interstitial water and ease of transferring mass. The response surface method was used to optimize the drying conditions of Pommelo slices by osmosis-hot air. The concentration of edible coating (0-2% w/v) and the time of applying ultrasound (0-30 min) and the concentration of sucrose (40-80% w/w) were evaluated as independent variables on the amount of moisture content, absorption of solids, weight loss and productivity coefficient of Pommelo slices as dependent variables. All process variables were linearly significant for all responses (P<0.01). The comparison of the optimization results of coated and uncoated Pommelo osmotic dehydration showed that at the optimal point, the maximum amount of carboxymethyl cellulose coating and the osmotic dehydration time and the concentration of the osmotic solution in the coated sample were calculated as 2%, 21.86 minutes and 57.75%, respectively. The highest values of water reduction, weight loss and efficiency coefficient were 0.09172 (g/100g of solid matter), 0.091% and 19.478 respectively in the coated sample, and the highest absorption of solids with a value of 0.0089 (g/100g of solids) was reported in the uncoated sample. The results showed that the use of coating reduces the absorption of solid.

The sprouting process includes changes in nutritional, biochemical, and sensory characteristics that improve chickpea quality and increase its digestibility. Various products such as Falafel are made from ground and dried chickpea sprouts. Therefore, in this research, the use of hot air (70°C), infrared (250 W), and microwave (220 W) methods for drying ground chickpea sprouts was investigated and modeled. The drying time of the samples in the infrared dryer was shorter than the other two dryers. The average drying time of the samples in the hot air, infrared and microwave dryers was 63.3, 26.7, and 156.7 min, respectively. In this research, the effective moisture diffusivity coefficient of ground chickpea sprouts in hot air, infrared and microwave dryers was determined to be 4.99×10-9 m2s-1, 17.95×10-9 m2s-1, and 1.59×10-9 m2s-1, respectively. To study the drying kinetics of ground chickpea sprouts, Wang and Singh, Henderson and Pabis, Approximation of diffusion, Page, Newton, Midilli, and Logarithmic mathematical models were fitted to the experimental data. Finally, when modeling the drying process of this product, Midilli's mathematical model with four parameters was chosen as the best model due to its minimal error.

 Due to the importance of product appearance quality in product grading and the impact of factors such as area, uniformity, and various defects on the product quality, and also, the ability to recognize these features at a very low cost, image processing techniques, is one of the methods used to evaluate food quality. Therefore, in this study, a non-destructive image processing method was used to investigate the factors affecting the color and shrinkage of apple slices during drying.

 Golden delicious apples were used in this research. The central part of the apple (including the rivet, seeds, and tail) was removed by a kernel separator and sliced into 3, 5, and 7mm thickness and approximately 7 mm diameter slices using a hand slicer without separating the skin. Three temperatures of 60, 70, and 80 °C were used to dry the samples. To determine the moisture content of a sliced apple, the samples were first weighed on a digital scale, then placed in a dryer, and the experiment was continued until the samples reached equilibrium mass. Due to the high importance of moisture ratio in controlling the drying process, moisture rate (MR) and moisture content (MC) were calculated, and samples were taken to investigate the amount of surface shrinkage, general color changes and browning index. After extracting L*, a*, and b* values, total color changes and browning index (to show the intensity of brown color in the product) for all samples before and after drying were calculated and evaluated to describe color changes after drying.

 The drying kinetics results showed that the drying process significantly depends on the thickness of the samples. According to drying curves, at the early stages of drying, the decrease in humidity occurs more severely and the graph has a steeper slope, but as the process continues and the moisture content of the product decreases, the slope of the curve decreases. In the early stages of drying, due to the presence of water inside the fresh fruit cells, there is a pressure balance between the fruit and the surrounding environment, which causes the fruit to remain swollen. However, as the drying time progressed, contractile stresses are created, which cause superficial shrinkage. In this study, it was observed that increasing the thickness from 3mm to 7mm, reduced the final shrinkage on the surface of apple slices by 11% at 60 °C, 12% at 70 °C, and 13% at 80 °C. After moisture leaves the surface of the product and heat penetrates into the product, moisture begins to leave the product by conducting interstitial convection. When moisture moves to the surface, the mechanical balance and consequently the textural structure of the sample is disturbed due to the creation of different spaces in thickness. According to the results, increasing drying time and thus decreasing the moisture content, increases the percentage of apple shrinkage. On the other hand, at a certain thickness, with increasing temperature, the percentage of shrinkage changes in the thickness of the product decreases. Therefore, at thicknesses of 3, 5, and 7 mm, the increase in temperature from 60°C to 80°C, decreased the amount of shrinkage thickness by 16, 12, and 8%, respectively. It is in higher thicknesses that react with heat and change the color of the fruit due to the Maillard reaction. After complete drying of apple samples, the highest amount of color change was related to the thickness of 7 mm and a temperature of 80°C, which was equal to 1.254. Also, the lowest rate of discoloration of apple slices in a thickness of 3 mm and a temperature of 60 °C was 0.889. The browning index (Bi) in the high thickness of apple slices is less affected by the process temperature due to the increase in moisture level. For this reason, the rate of browning was very low among the experimental samples and the highest rate of browning was related to the thickness of 7 mm and the temperature of 80 °C was 585/2559. Also, the lowest rate of browning of apple slices was observed in the thickness of 3 mm and the temperature of 60 °C was 584.254.

 Finally, it was found that the thickness and temperature factors can have an effect on the quality of product during drying process. The results of this study can provide a cheap and fast way to control the quality of fruits during drying and help producers of these products select the main process factors that affect the final quality.

Dunaliella salina unicellular alga belonging to the Chlorophyceae family has been introduced as a extensive source of carotenoids (Zenouzi et al., 2013; Mendiola et al., 2008). The Carotenoids are strong antioxidants and bright pigments, and for this reason are used as human food and aquatics diets pigments (Denery et al., 2004). Investigations have shown that increasing the drying temperature will decrease the volatile and phenolic compounds of algae, and by decreasing the drying temperature, the amount of these compounds in the algae will be increased (Ling et al., 2015). According to the other research, the amount of beta-carotene after drying has been greatly decreased in conventional drying methods. (Ihns et al., 2011; Karabulut et al., 2007). The supercritical drying is an extraction process, that the supercritical fluid is the extraction solvent and water is the soluble substance (Brown 2010). The advantage of this drying method is that it is possible to prevent vapor-liquid contact in the homogeneous phase. For this reason, the tensile stress caused by the capillary that occurs during the air drying process does not exist in supercritical drying, and protects the structure of the material (Namatsu et al., 1999). In addition, carbon dioxide easily reached to critical temperature (31.1°C), so operating at low temperature (significantly lower than common dryers) prevents thermal damage (Brown 2010). Also Ultrasonic power at low frequency (20 to 100 kHz) is used for bacterial inactivation, improving process speed, heat and mass transfer, and water removal. In addition, the phenomenon of cavitation occurs in this composition and it causes an increase in the micro-mixing and communication between the solvent and microorganisms, and as a result, water exit and bacterial inactivation are improved (Morbiato et al., 2019). Non-contact ultrasonic, such as airborne processes, in which there is no contact surface or liquid to connect the transducer and the desired surface, can be used in various applications, including food drying. This system in combination with the other methods can overcome the limitations. For example, high temperature drying can damage the components of the material (color, texture, volatile compounds, etc.), while the combination with airborne can decrease the temperature and thus reduce the drying time, and the quality of the product and its nutritional ingredients should be maintained. The present work focused on investigation of the kinetics and drying rate of the Dunaliella salina algae by the supercritical carbon dioxide method in combination with airborne ultrasonic power, as well as the modeling of drying using mathematical and response surface methods.

The studied algae in this research was Dunaliella salina, which was obtained from the Artemia & Aquaculture Research Institute of Urmia University. In this research, 2.8 grams of algae paste with a thickness of 3 mm was placed in the drying vessel and methanol was added directly to the sample as a co-solvent. And the Suprex (MPS/225) in combination by airborne ultrasonic was used. The vessel that used in devise was made by stainless steel 316. Face center design consisting of 20 experimental runs with six replications at the central point was utilized to determine the effects of three independent variables in three levels: -1, 0, +1. The independent variables were Pressure at three levels (80, 110, 140 bar), temperature at three levels (40, 50, 60 °C) and airborne ultrasonic power at three levels (0, 20, 40 w) and the samples were weighed in dynamic mode in 30 minute intervals. The software of Design-Expert 13.0.5 (Stat-Ease, Minneapolis, MN, USA) was used for design experiment, data analysis and surface responsible diagram.

In 80 bar of pressure, the reduction of moisture content was constant for 150 min in temperature of 40 °C and without ultrasonic power and then was reduced. In other treatment the reduction of moisture content was continued for 120 min. In this pressure, after 180 min the moisture content in 40°C reached to 52% and in 60 °C and 40 w ultrasonic power reached to 31%. In 110 bar of pressure, the lowest moisture reduction was reached to 44% at 40 °C and 20 w. and the highest moisture reduction was 33% at 60°C and 20 w. The moisture reduction was constant for 120 min in temperature of 40°C and 20 w, while in temperature of 60°C and 20 w, the moisture content was constant for 90 min. in pressure of 140 bar, the maximum of moisture content was in 40 °C and without ultrasonic power and the minimum moisture content was 22% in 60 °C and 40 w. These results are due to the low viscosity, high diffusion rate and the near-absence of surface tension of the supercritical fluid. These properties allow the supercritical fluid to easily penetrate into the micro pores and surface and internal cells. Furthermore, new pores or channels could have been made by the supercritical fluid (Lee et al., 2011). The Midilli et al. model was the best ftting model. The highest values of R2, and the lowest values of SSE and RMSE obtained for the Midilli et al. model were 0.99925, 0.00023 and 0.0004, respectively. In RSM modeling, the results show that the changes of pressure, temperature and ultrasonic power had significant effect on moisture ratio in weighting time. While the interaction effect of independent variables had no significant effect on the factors. and the model has been investigated linearly. In the drying rate curve, at the beginning, drying was increased with a great slope, and then the curve decreases with a lower slope. The lowest drying rate at a pressure of 80 bar was occurred, in temperature of 40°C and the without ultrasonic power. And the highest drying rate was observed, in 60 °C and 40 w. the lowest drying rate in pressure of 110 bar was occurred in 40°C and 20w.

According to the results, the supercritical carbon dioxide method in combination with airborne ultrasonic power was suitable for dunaliella salina drying at low pressure and temperature. But in order to reduce the drying time and final moisture content, the pressure, temperature and ultrasonic power can be increased.

In this research , The kinetics of drying , The Determining The effective Moisture Diffusivity, Activation Energy, And also the prediction of the moisture ratio of red onion during the dry process with dryer-hot air drying were carried out with the help of mathematical models and fuzzy neural inference system (ANFIS). The experiments were performed at four levels of temperature at 50, 60, 70 and 80 0C and a constant air flow rate of 1 m/s . To select a suitable drying model, twelve thin layer drying models were used, as well as using fuzzy neural inference system R Software version 3.6.2. The results showed that among the mathematical models, The binomial model with the highest coefficient of explanation and the lowest root mean square error was the most suitable. The results of the correlation coefficient value (R2 = 0.999 and error) RMSE = ( 0.002) the lowest root mean square error It predicted the humidity ratio better than mathematical models. Effective Moisture Diffusivity for four temperatures, Respectively (0.03136255,0 0211698,00193770.001847669 0) M2/ S and The amount of activation energy was 1890.4 (kJ /(kg.K).

Non-uniform drying and head rice reduction due to non-movement of paddy in common fixed bed dryers is one of the basic problems in rice milling factories. In order to investigate and provide a suitable drying method with the approach of creating uniformity in drying process, reducing losses, and saving energy consumption, a two factorial experiment in completely randomized design (CRD) was used. The factors were the initial moisture content (IMF) of paddy at two levels (16 and 18%) and drying method at 4 levels (one-way air flow, reverse air flow in 1 hour, 2 hours and 3 hours and then continuation of drying process the same as one-way airflow). The same drying air temperature and air velocity was considered for all treatments. In both moisture treatments, three hours reverse air flow drying has the highest head rice (75.7-75.86%) and the lowest energy consumption (41-49 MJ/kg water). The highest energy consumption with the amount of 79 and 67 MJ/kg water was belonging to the paddy with high and low IMC, respectively. In one way airflow, dried paddy in 10 cm from the bottom layers of dryer has the lowest amount of head rice (63.65%). In both moisture treatments, the results of mixed layers showed that one hour reverse air flow drying with values ​​​​of 68.28-68.68% had the lowest head rice. Also, drying method had no significant effect (P>0.05) on the cooking quality.

Unfortunately, the food processing waste has recently increased, prompting researchers to develop new economical products based on food waste to reduce the environmental problems caused by waste accumulation.  Among these, carrot pomace as a nutrient-rich waste with appropriate functional properties can be mentioned. In this study, fresh carrot pomace was dried using a hot-air oven (60℃ and 80℃) and a freeze dryer. Then the dried-pomace quality in terms of functional properties (bulk density, particle size, water and oil holding capacity, antioxidant activity, carotenoid content, color, and microstructure) and chemical compounds were examined. The results showed that the drying method and temperature had a significant effect on pomace’s chemical compounds. A significant decrease in moisture and lipid content was perceived due to the oven temperature increment (from 60℃ to 80℃), while no significant changes were observed in crude fiber content. Freeze-dried samples also had the least moisture content in comparison to the oven-dried samples. Also, the functional properties of the dried samples showed that the drying method and temperature had no significant effect on the carotenoid content and particle size of the samples. The oven temperature increment significantly reduced the bulk density and water holding capacity (from 15.97 to 14.57 g/g). The freeze-dried sample also showed the lowest bulk density, the highest water and oil holding capacity, and antioxidant activity compared to the oven-dried counterpart. It also had better color and more porosity. Therefore, freeze-dried carrot pomace can be used to fortify food products.

Raisin is one of the important export products in the agricultural sector, but there are several challenges in increasing the quality of raisins and their competition in foreign markets. The type of drying place and environmental conditions can have a great impact on the quality of raisins. In this study, the aim is to modify the traditional grape drying place, using intelligent heating plates. The seedless grape was harvested at two different times and prepared by two methods, natural (without pretreatment) and treated with alkaline solution and dried in traditional place with concrete floor and traditional place modified by control heating plates. The results showed that the drying time of non-treated raisins was 2.36 times of alkali-treated raisins and the drying time of traditional place was about 4.75 times of modified place. Also, the total count, coliform, molds and yeasts in the traditional drying place were higher, but the number of lactic acid bacteria was less than the modified method (P <0.05). In alkali-treated raisins, the total count, coliform and mold were lower, but the number of lactic acid bacteria and yeasts was higher than natural raisins (P <0.05). The results of sensory evaluation also showed that the color score of samples with alkali-treated raisins was significantly higher than other. The amount of energy consumed to prepare one kg of raisins in 21th September and 12th October was 0.98 and 1.78 kWh, respectively, and for natural raisins, this amount was 1.63 and 5.5 kWh, respectively. According to the results obtained in this study, it is possible to prepare raisins with high hygienic quality and desirable sensory properties by harvesting grapes in a timely and drying in the place with intelligent heating plates

One of the ways to reduce the drying time is to supply heat by infrared radiation. Infrared technique could be used as a substitution to the current drying techniques for manufacture a high quality dried hydrocolloids. Infrared technique has many advantages such as: high heat transfer rate, uniform heating, low processing time, high performance (80-90%), lower energy utilization, lower energy costs, and improving final products quality (Aktaş et al. 2017; Salehi 2020b). Edible coating applied to food slices prior to drying is a technology that can improve the nutritional and sensory qualities of dehydrated products. The edible coatings have been widely studied aiming to increase shelf life of minimally processed products and reduce the solids uptake during osmotic dehydration. Polysaccharide edible coatings present low water vapor barrier; however, they present good gas barrier properties, such as oxygen barrier, and could be used to minimize oxidative reactions in food during drying, pointing out the potential of using edible coatings prior to convective drying, since it could reduce undesirable changes due to large time of exposure of the food to oxygen (Fakhouri et al. 2007; Garcia et al. 2014; Salehi 2021; Satorabi et al. 2021). The performance of artificial neural networks (ANN) as an analytical alternative to conventional modeling techniques was reported by some researcher. They reported that this approach is able to estimated drying kinetics of various fruits and vegetables with high precision. It has been shown that nonlinear approaches based on ANN are far better in generalization and estimation in comparison to empirical models (Bahramparvar et al. 2014; Zhang et al. 2014; Salehi 2020a). In this study, basil seed and xanthan gums were used to coating of peach slices during drying in the infrared system and the drying kinetics of the samples were investigated.

Slices of peach (5 mm thick) were prepared with the aid of a cutter and a steel-made cutting tool, which was cylindrical in shape and pointed on one of the sides. Basil seeds was physically cleaned and all foreign stuffs were removed. Then, the pure basil seeds were immersed in water for 20 min at a seed/water relation of 1:20 at 25°C. In the next step, the gum was separated from the inflated seeds by passing the seeds through an extractor (Bellanzo BFP-1540 Juicer, China) with a rotating disc which scratches the mucilage layer on the seed surface. The initial moisture content (MC) of the basil seed gum was 99.4% (wet basis). Xanthan and basil seed gums were used to coat the fresh peach slices. A 0.6% (w/w) xanthan and basil seed gums solution were prepared at 25°C and then peach slices were immersed for 1 min in a aqueous solution. The coated peach slices were dried in an infrared dryer (infrared radiation lamp (NIR), Noor Lamp Company, Iran). The influence of infrared radiation power (at three levels 150, 250 and 375 W), and time (min) on drying kinetics of peach slices was examined. The weight changes of peach slices was measured by using Lutron GM-300p digital balance (Taiwan, the sensitivity of ±0.01 gr). All measurements were done in triplicate. In this study, the Neurosolution software (release 5, NeuroDimension, Inc., USA) was employed for making the ANN model. The experimental data order was first randomized and then total data were randomly separated into 3 partitions: training (20%), validating (20%), and testing data (60%). The testing data were used for prediction of the trained network performance on unseen data. In the hidden layers and output layer a hyperbolic tangent activation function was used. The Levenberg–Marquardt (LM) optimization method was applied to network training. Also, a sensitivity analysis was done to supply the measure of relative significance between the inputs of the ANN model and to show how the model output changed in response to input changes.

Fruits and vegetables drying is a commonly used process for improving product safety as it greatly decreases the microbial activity and enzymatic changes during the storage period, hence, increasing the shelf life of the product. In this study, the effect of coating variables (control, basil and xanthan) and infrared lamp power (150, 250 and 375 W) on drying time and moisture content of samples in three replications were investigated. The concentration of used gum was 0.6% (w/w), the thickness of peach slices were 0.5 cm, and the distance of samples from lamp were 10 cm. The results of peach samples drying by infrared method showed that with increase in lamps power the drying time decreases. Coating pretreatment increased the drying time of peaches and the drying time of samples coated with basil seed gum was longer. The average drying time of the control samples, coated with basil and xanthan gums was 52.78 min, 76.22 min and 62.00 min, respectively. This process was modeled by an artificial neural network with 3 inputs (radiation time, type of coating and radiation lamp power) and 1 output (moisture content). The results of artificial neural network modeling showed that the network with 7 neurons in a hidden layer and using the Hyperbolic tangent activation function can predict the moisture content of coated peach during drying using infrared dryer (r=0.999). Also, the values of mean squared error (MSE), normalized mean squared error (NMSE) and mean absolute error (MAE) for optimum network were 0.3123, 0.0004 and 0.4065, respectively.

Polysaccharide-based edible coating can be useful as a pretreatment for drying, since they prevents the oxidation of nutritional compounds, thereby improving the quality of the dried product. In this study, the effects of polysaccharide coating (xanthan and basil seed gums) on the drying kinetics of peach slices were investigated. In addition, artificial neural network model was used for prediction of moisture content of coated peach slices in an infrared dryer. With increasing infrared intensity, due to the increase in peach slices temperature and increasing evaporation rate and the decrease in drying time, the specific energy for drying of peach slices decreases. The results of this study indicated that ANN approach could give good estimation of moisture content of coated peach slices by xanthan and basil seed gums during infrared drying.

Among the various hot air drying methods, fluidized bed drying has significant advantages such as high heat and mass transfer, uniform moisture reduction of products with short time and high drying rate and uniform process at entire surface of the product due to efficient mixing with the drying air and high efficiency of process. In recent years, usage of infrared drying to dry food products has increased over conventional drying methods due to higher product quality, uniform heat distribution, high energy efficiency, high heat transfer rate and less processing time, facilitating the control of raw material temperature, reduced necessity for air flow across and the high ability to control process parameters in infrared heating. In this study, kinetics of carrot cubes drying by infrared-fluidized bed dryer were investigated.

Fresh carrot were washed with tap water and peeled manually then diced by dicer. To drying carrot cubes by combined infrared- fluidized bed method a laboratory scale dryer was designed and performed. In this study, drying of carrot cubes (0.5 and 1 cm3) was performed in factorial design experiments using air temperatures of 50, 60 and 70 °C and three levels of infrared power (200, 400 and 600 W) in three replications. To describing the infrared-fluidized bed drying behavior of carrot cubes, five mathematical models (Page, Modified Page, Henderson & Pabis, Midilli and Logarithmic) were evaluated.

The results demonstrated that the change in inlet air temperature, size of carrot cubes and infrared power had a significant effect (P <0.05) on water withdrawal from the sample and drying time decreased with increasing air temperature and infrared power and decreasing carrot cubes size. Therefore, the energy consumption was also reduced considerably, decreasing from 12.63 Kwh/kg in bed fluidized method (without infrared power) to 2.28 Kwh/kg using infrared -fluidized bed drying. The Page model was identified as the suitable model to describe the drying kinetics of carrot cubes by infrared-fluidized bed dryer that showed a good agreement with experimental data.

The statistical analysis of variance showed that air temperature, sample size and infrared power had a significant effect on water withdrawal rate of samples and therefore drying time. According to the results, using infrared-fluidized bed drying as a combined method in comparison with conventional hot air drying methods can reduce drying time and energy consumption and costs considerably.

In this study, the effect of ultrasound pretreatment, air velocity and temperature on cornelian cherry shrinkage during hot air drying process were investigated. Ultrasound pretreatment at two time levels (10 and 30 minutes) was applied and then the samples were dried at 40, 50 and 60°C and 1, 1.5 and 2 m/s air velocity. Afterwards, shrinkage data were fitted to three experimental models. The results showed that with decreasing moisture content during drying, the thickness of the samples reduced from 0.0138 to 0.0078 m. The application of ultrasound pretreatment led to a significant (P<0.05) decrease in thickness. Moreover, one of the models was selected as the best suitable model in predicting thickness changes of cornelian cherry (R2=0.99) under the experimental conditions. Through multiple regression analysis, the relations between the coefficients of the models with the variables used were obtained.

Corn seed contains almost 5.5% of oil of which about 85% can be found in germs of seeds. Proper steps are necessary to take, from the point of view of harvesting time and percentage of moisture retaining in the seed during harvestinh time, to improve the quality of oil extracted from the seeds. In the present study, the effects of temperature at four levels (45, 55, 65 and 75 °C), seed moisture content at harvest time at three levels (30, 35 and 40% (d.b)), and hot air velocity at two levels (1 and 2 m/s) on the total oil content, oil color, free fatty acids and peroxide value were investigated. A factorial experiment in a completely randomized design was used to analyze the data and the mean comparison was conducted by Duncan's multiple-range test at α = 5%. Based on the results, the most appropriate drying temperature was found 55 °C, and the best moisture content at harvest time was found 30% d.b and the best hot air velocity was found 2 m/s. The peroxide value of samples (before drying and in all dried samples) was not significant because the treatments were not given enough time to begin the oxidation mechanism.

The use of edible coatings can help reduce the undesired effects caused by the drying process of fruits and vegetables. In this study, the influence of two different edible coatings including basil and chitosan (0, 0.5 and 1 %) on drying kinetic, color, texture and antioxidant activity of apple slices were evaluated at different temperatures (40, 50 and 60 ˚C) in hot air oven and vacuum drying. The results showed that the use of different coatings in both drying methods increased the drying time. Fitting of different mathematical models on the experimental data showed that the Midili model for basil coatings and the approximation of diffusion model for chitosan coatings are able to predict the moisture content more accurately than other models. With increasing coating concentration or decreasing drying temperature the lightness, adhesiveness, cohesiveness and antioxidant activity enhanced. But, the redness, yellowness, brownness, total color difference and hardness diminished. Generally, basil and chitosan coating pretreatment could be considered as an effective approach to improve the quality of the dried apple fruit in drying industry.

The efficiency of several theoretical models to predict the moisture content of pear slices during drying were evaluated and compared. Pear slices were dried at 5 different temperatures (30-40-50-60-70oC) and the moisture diffusivity and convective mass transfer coefficient were estimated. In the next step, mass transfer model was developed by using mathematical solution of Fickchr(chr('39')39chr('39'))s second law of diffusion with different numerical and analytical models. The results of the studied models indicated that the both numerical models were substantially more accurate than analytical model in describing the experimental drying curves. However, the best result was obtained with the combined model developed in this study. This model presents the highest coefficient of determination (R2) value (0.999), and the lowest root mean square error (RMSE) value (0.06). The higher accuracy of this model can be attributed to the fact that this model takes into account the term that simulate the convective moisture transport and chooses the appropriate boundary conditions. By applying this model, it is possible to predict moisture variations in pear slices with high accuracy as a function of internal variables (thickness, chemical composition) and external factors (temperature, relative humidity and air velocity).

Dehydration of fruits and vegetables is a widely used unit operation (Funebo et al., 2000). Intermittent infrared radiation, in which the product surface maintained at constant temperature, is a novel drying method to produce high quality dehydrated fruits and vegetables (Zhu & Pan, 2009; Zhu et al., 2010). One of the most important physical changes in the quality of food during drying is the decrease in external volume. This change in volume is called shrinkage and is an unavoidable phenomenon during the dehydration process. Shrinkage is usually expressed by the ratio between the volume of the sample after and before drying (Yan et al., 2008). Shrinkage also affects the porosity of dried materials and it is the parameter determining about the mass transfer properties, mechanical properties, and the texture of food product (Witrowa-Rajchert & Rząca, 2009). The three qualitative parameters such as the degree of shrinkage, density and firmness of the product are related to each other (Funebo et al., 2000). Maximal shrinkage and structural collapse were shown to decrease until kept quality characteristics (Barzaghi et al., 2008). The factors affecting shrinkage include volume of water extracted from the product, mechanical mobility of the solid matrix, drying rate, and process conditions such as temperature, air flow rate, and relative air humidity (Moreira et al., 2000). The important consequences of shrinkage occurring during drying result in a loss of rehydration ability. Dehydrated products are usually rehydrated prior to their use (Krokida, M, & Marinos-Kouris, 2003). The rehydration behavior is studied as an indicator of texture damage (Giraldo et al., 2006). Rehydration is a complex process that is intended to restore the properties of the fresh product by contacting dehydrated products with a liquid phase. This process to be composed of three simultaneous steps: (1) absorption of water into the dry material, (2) swelling of the rehydrated product, and (3) loss or diffusion of soluble components. Rehydration ability or capacity measures the ability of a dehydrated product to rehydrate (Maldonado et al., 2010). Mathematical models of rehydration will be useful in designing and optimizing this operation that have been applied as exponential models or capillary absorption theory or Fick’s diffusion laws (Lee et al., 2006). In this research, the effect of this heating method on the physical-qualitative characteristics of dried apple slices, including volume, density, shrinkage and behavior of rehydration were studied. Apples (Golden Delicious variety) were purchased from a local market and according to Acevedo et al., 2008 kept in 0°C±1°C and relative humidity ranging from 90% to 95%. The samples were skinned manually and then cut into slices with different thicknesses of 5mm, 9mm and 13mm and all with 20mm in diameter. The average moisture content of apple was measured using oven (Binder FD53) at 103 °C for 24 hours and it was equal to 84.11% based on wet weight (AOAC, 2000). Operation of infrared radiation with intermittent heating method was performed at three constant temperatures of 70, 75 and 80 °C using the infrared dryer similar to Liu et al., 2014. Shrinkage coefficient of product was estimated with both theoretical (βtheo) and practical (β) methods according to Talla et al., 2004. Also, the mathematical models as Peleg (Reyes et al., 2011) and Exponential (Krokida et al., 2003) equation were compared to describe the rehydration process in dried product using adjusted R-squared (Adj.R2) and root mean squared error (RMSE). Statistical analysis of the effect of thickness and temperature on the shrinkage coefficients (βtheo, β) was performed in SPSS software in version of 19. To achieve this aim, a completely randomized design (CRD) with factorial arrangement with two factors as thickness (at three levels) and temperature (at three levels) was used. Also, two methods of computing the shrinkage coefficients (theoretical and practical) were compared together with one-way F test. Mean comparison was performed by Duncan test with 95% confidence level (P<0.05). All experiments were performed in three replications. The results showed that increasing of the temperature caused greater volume and density changes during rapid dehydration of the product. The density changes were more intense for the thin product (reducing the final density to about 0.6 g/cm3). Also for thicker products, the density changes were slower during the process (reducing the final density to about 0.7 g/cm3). During process, the variation of product shrinkage indicated an exponential rising trend which was influenced by the amount of evaporated water. Shrinkage coefficient is significantly increased at higher processing temperature and thickness of product (β equal to 0.164), representing that the product is heavily affected by the structural collapse phenomenon. The observations were similar to those reported by many researchers (Mayor & Sereno, 2004; Nowak & Lewicki, 2004; Katekawa & Silva, 2006). The temperature of 80 °C showed significantly higher theoretical and practical shrinkage coefficient than the other two tested temperatures (70, 75 °C). The difference between the two methods of calculation in shrinkage coefficient (theoretical and practical) was also significant and the difference increased with the increase of temperature (more than 6%). Jannot et al., 2002 reported that the error in the practical method can be due to the noisy data (deviation from the actual value). Limitation of rehydration capacity (RC) in slices with high shrinkage stress confirms the damage of the texture of the product (reduction in predicted equilibrium moisture content: Xe from 6.523 to 4.148 kg/kg, db). Rehydration process in different product thicknesses is described better using Peleg model (higher Adj.R2 and lower RMSE) compared with the exponential one. The observations were similar to those reported by many researchers (Krokida, M, & Marinos-Kouris, 2003; Nathakaranakule et al., 2010). The physical properties including shrinkage and density in the dried product are affected by process and product conditions. The low occurred shrinkage that reflects the preservation of the internal structure of the product and will be effective in rehydration behavior. In fact, reabsorption cannot be simply defined as the returned process of dehydration. Because of moisture reabsorption is completely affected by the texture, structure and properties of the dried product. Therefore, mild thermal conditions prevent the structural breakdown of apple slices and, at low thicknesses, due to the reduced volume of water evaporated from the slices, the shrinkage coefficient is reduced, thus preserving the internal physical structure of the infrared dried product.

By controlling dehydration and rehydration conditions, optimal reconstitution properties can be achieved. Therefore, mathematical models that describe the kinetics of moisture removal and moisture uptake are important in designing and optimizing that process. In this study, the drying process of pear slices at 5 different temperatures was investigated and the effective diffusion coefficient of the samples was determined. Drying data were also fitted with 9 mathematical models. The hydration process of the dried samples at 50°‌C was also fitted with 4 different models. The results showed that the effective diffusion coefficient has an increasing trend with increasing temperature and its temperature dependence can be described by Arrhenius equation. Among the dehydration models, two models (logarithmic and Weibull) were better than other models in predicting changes in sample moisture during drying and the best model for the rehydration process was Peleg model. In the last step, the temperature dependence of the constants of these equations were fitted with Arrhenius and exponential decay models.

Drying is one of the oldest methods of food and agricultural products preservation, which increases their shelf life by removing a part of the product water content. Long-term storage, minimizing the storage and packaging needs, reducing the transport costs, and producing a variety of products are the most important reasons of food drying. Application of some pre-treatments before drying such as osmotic dehydration is suggested to improve the quality of the dried food products. Osmotic dehydration is a process that used for partially dehydration of fruits and vegetables, by immersing them in a concentrated solution of sugar or salt (Sutar and 2007). Reducing the drying time, limiting the heat damages, improving the textural quality and vitamin retention, flavor enhancement and color stabilization are some advantages of the osmotic pretreatments (Sutar and Sutar 2013). Osmotic dehydration removes water from the fruits and vegetables up to a specific level, which is still high for food preservation, so this process must be followed by further processes in order to lose the most portion of the fruits and vegetables water content. Air drying can be used to remove the remaining water from the osmo-dehydrated product (Shahade et al 2015). Salts and sugars are the common solutes that mostly used for osmotic treatment. The quality characteristics of final product in salt-treated samples are higher than sugar-treated products and the preventing of the undesired reaction products formation are from advantages of salt over other solutes (Shahade et al 2015). Onion is a famous spice that is grown all over the world and consumed in various forms. This vegetable is used as an appetizing, healthful and digestive food because of its high nutritional quality and therapeutic properties. Onion is a product that is consumed throughout the year, but its production is seasonal. This product is a perishable food due to its high moisture content. Some environmental factors such as microorganisms, enzymes, and surface vaporization of moisture content leads to spoilage of onion during the storage (Shahade et al 2015; Sahu et al 2017). Drying is a major processing operation in the food industry that can be used to enhance the storability, improve the quality and minimize packaging and handling costs of onion. Drying of onion with the usual drying method causes undesirable changes in sensorial properties such as texture, color, taste and serious decreases in nutritional value of dried product. Pre-drying treatments, such as osmotic dehydration has been suggested to improve the quality of dried onion. It seems that the osmo-air drying can be an appropriate method to increase the shelf life and improve the quality of dried onion without adversely affecting its sensorial and nutritional value (Sahu et al 2017). The effect of osmotic dehydration process parameters on onion dehydration kinetics and optimization of process conditions has been investigated by some researchers (Alam et al 2013; Hussein et al 2018; Patil et al 2012; Revaskar et al 2014; Shahade et al 2015). But the few studies on the characteristics of dried onion with osmotic pretreatment have been done. The purpose of this study was investigating the effect of osmotic solutions compositions on dehydration amount and quality attributes of osmo-air dried onion slices.

Fresh yellow onion was procured from the local market. The onions were peeled carefully and washed and then cut into 3.0±0.1mm thick slices using a manual stainless steel cutter. The osmotic solutions of different compositions were prepared by dissolving required amounts of salt, sugar and citric acid in distilled water. Five solutions of different compositions were used for osmotic dehydration of onions (T2 (10% NaCl), T3 (10% NaCl and 10% sucrose), T4 (1% citric acid), T5 (10% NaCl and 1% citric acid) and T6 (10% NaCl, 10% sucrose, and 1% citric acid). Solution to sample ratio was kept as 2.5:1 in each experiment. The samples were immersed in osmotic solutions for 1 h at room temperature (25 °C). All Samples were weighed after removal from osmotic solutions and dried in a laboratory oven at 65 °C until to reach 6% moisture content (Shahade et al 2015). The moisture content of the fresh and osmotically dehydrated onion slices was measured by oven drying method at 105 °C and the amount of water loss, solid gain and weight reduction of the samples were calculated. The dried onion slices were evaluated in terms of physicochemical (rehydration rate, pH, color, vitamin C and total phenolic compounds) and sensorial (Color and appearance, texture, Taste and flavor and Overall acceptability) properties. The rehydration ratio of dried onion was calculated after flooding 10 g of dried samples in 1000 mL of distilled water at 22±1 °C for 5 h (Patil et al 2012). The pH value was measured by a digital pH meter. The color measurement was done using a colorimeter (TES-135A, Taiwan). In order to determine the total phenolic contents, the Folin–Ciocalteu method was employed and measurements were done at 765 nm with a spectrophotometer (UNICO 2802, China) (Taga et al 1984). The vitamin C content was determined by Indophenol method and measurements were done at 515 nm with a spectrophotometer (Klein and Perry 1982). The sensorial evaluation was carried out by 5-point Hedonic Scale. The dried onion slices were investigated for the sensorial attributes by 20 trained panelists. The panelists were asked to evaluate the samples and score them between 1 (most disliked) to 5 (most liked). The statistical model that used was completely randomized design. The experiments were performed in 3 replications and analysis of variance (ANOVA) of data was conducted using MSTAT-C software. Differences between the means values were also determined using Duncan’s Multiple Range test (p < 0.05).

The results of this research showed that the compositions of osmotic treatments had a significant effect on weight loss, water loss, solid gain, physicochemical characteristics and sensorial properties of dried onion slices. The highest weight loss, water loss and solid gain were related to the pretreated onion by the solution containing three solutes (salt, sucrose and citric acid). The presence of citric acid in the osmotic solutions significantly decreased the pH value of the final product. Although the osmotic pretreatments decreased the L* value, but the dried onion slices pretreated with sucrose and salt solution had the highest b* value. The Millard's browning reactions produced brown pigments in the dried product and the evaluation of the browning index showed that the application of the osmotic pretreatments especially with citric acid containing solutions increased the browning index of the dried onion slices. The least undesirable color changes were observed in onion slices pretreated with salt solution. Also, the osmotic dehydration with T6 treatment (salt, sucrose and citric acid) had the greatest effect on preserving of vitamin C and total phenolic compounds. As compared with control the use of the osmotic pretreatment reduced the rehydration ratio of the product. The most rehydration ratio after control was related to onions treated with citric acid solution (T4). Also, the results showed that the presence of sucrose in the osmotic solution increased the rehydration ratio of dried onion slices.Althoughthecolorscoreofosmoticdriedonionsliceswaslowerthanthecontrol, butthe osmoticpretreatmentsimprovedthetasteandincreasedtheoverallacceptabilityofthedriedproduct.

Osmotic pretreatment of onion slices with a multi-component osmotic solution (salt, sucrose and citric acid) caused the optimal results in terms of sensory and physicochemical properties.

Rosemary is an evergreen and aromatic plant of the mint family, which has many antioxidant and medicinal properties. Nowadays, to increase the quantity of extraction and improve the quality of essence, the plant is dried and then the extraction process is performed. Thus, new and combined methods for drying of plants containing essence have been studied. Different drying methods such as hot air, microwave, microwave- vacuum, sun and freeze drying have been studied by many researcher to dry rosemary and the quality of the extracted essence and the kinetics of mass transfer have been investigated. Drying by means of infrared is considered for many agricultural products but this method has not been applied to rosemary until now. Therefore, the purpose of this study was to investigate the kinetics of drying and the effect of infrared drying on the volume, color and quality of essence of rosemary leaves. Our specific target was modeling of the infrared drying process and compare it with other drying methods.

In this study, the geometric properties of rosemary leaves were measured by Mitutoyo Micrometer. Then, by using electromagnetic radiation in the range of infrared spectrum (100, 200 and 300watts) freshly prepared leaves of rosemary were dried. After essence extraction by clevenger method, the volume of extraction and components were determined by GC/MS and according to the power of infrared wavelength were evaluated by completely randomized design. The quality of dried rosemary and essences were also studied by ImageJ software, and color parameters a*, b*, L*, chroma (C*), browning index, total color difference and Hue angle, were calculated by completely randomized design. In addition, drying curves, effective diffusivities and activation energy determined by using moisture measurement data.

According to the results of analysis of variance and Duncan's Multiple Range test at 5% level, it was observed that with increasing the power of the infrared lamp in the drying process, color parameters like L, b, Chroma and BI in dried rosemary decreased and ΔE, A and Hue angel increased. Analysis of variance and comparison of Duncan's mean at 5% level showed that increasing the infrared power has a significant effect on reducing the volume of essence. In the case of essence color, it was perceived that with increasing the power of the infrared lamp, the color parameters like A, L and Hue angel decreased and b, BI and Chroma increased. Furthermore, increasing the infrared power in the drying process of rosemary has a significant effect on reducing the volatile compounds of rosemary essence. Effective diffusivities varied from 33.3×9.10-9 to 1.0907×10-8. The activation energy was also determined as 30.243 kW/kg. To predict the rosemary drying trend by using eight models, regression modeling was performed through MATLAB software (version 2016). Results showed that, Midilli model for the power of 200 and 300 watts and Verma model for the power of 100 watts, due to high correlation coefficient index and low standard error, were two suitable models for evaluation of Drying kinetic and prediction of drying process.

Increasing infrared power during drying process of rosemary leaves decreases the efficiency of essence extraction. Moreover, increasing the infrared power has a significant effect on reducing the active ingredients like cineol and Beta-Pinene in essence. The color of dried rosemary and extracted essence are affected by infrared radiation power and varies with increasing the power. Rising the infrared radiation power results in an increase in the effective diffusivity coefficients. Also, it can be concluded that, midilli and verma are two best models for prediction of drying trend of rosemary.

The aim of this study was to use the Response Surface Method (RSM) model to design, test and optimize the drying process of fillets of common carp (Cyprinus carpio) using infrared radiation. The power of infrared radiation was 83, 104 and 125 watts and the power of the IR-lamp was 250 watts and its distance from the fish fillet was 5 cm. Pieces of fish fillets were weighed at intervals of 60, 120 and 180 min with a digital scale with an accuracy of 0.01 g. Radiation power (A) and irradiation time (B) were effective in reducing the amount of moisture and the effect of quadratic radiation power and irradiation time were significantly more effective in comparison with their linear effect in reducing the amount of moisture. However, the power of radiation played a more important role compared to the time of radiation. The drying rate of the fillets increased with lower irradiation time and higher irradiation power, so that the drying speed of the fillets improved in the minimum irradiation time (60 min) under high irradiation power. Effective moisture permeability was reduced at low irradiance and low radiation time. Based on central composite design models, treatment 2 with 125 watt power and time of 60 min (moisture of 1.32 g of water/g of sample weight, drying speed of 0.022 g water/g sample weight per minute and effective moisture permeability 1.25846E-007 m2/s) improved the shelf life of fish fillets.