Food Engineering
Behdad Shadidi; Reza Amiri Chayjan
Abstract
The drying of food can extend the shelf life of food, reduce transportation and storage costs. Fick's second law is commonly used to evaluate the mass data in the drying process in a standard way and is based on many assumptions. Understanding the meaning of mass transfer in products can improve the ...
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The drying of food can extend the shelf life of food, reduce transportation and storage costs. Fick's second law is commonly used to evaluate the mass data in the drying process in a standard way and is based on many assumptions. Understanding the meaning of mass transfer in products can improve the drying process and product quality. Computational fluid dynamics (cfd) models fluid flow situations utilizing powerful computer and applied mathematics in order to predict mass transfer in industrial processes. The aim of this research was numerical study of the drying behavior of pistachio nut using CFD method and evaluating the numerical results in the bed condition of fluid, semi fluid and fix bed as well as air temperatures of 90, 75, 60 and 45°C. During drying using computational fluid dynamic and the Fluent CFD code, the external flow and temperature fields around the cylindrical object (7.5× 10 millimeter) will be predicted in the numerical analysis. A laboratory fluid bed dryer was used for drying experiments. The main parts of the dryer are forward radial fan, drying chamber, electrical heater, inverter, temperature controller. The dryer attachment tools are input and output temperature sensors, anemometer and computer. The numerical part was verified and juxtaposed with the experimental data. The numerical solution result at 60, 75 and 90°C were so close to experimental results except for air temperature of 45°C. Mean absolute error in fix bed, at 60, 75 and 90°C were 0.2123, 0.1257 and 0.0337 which were lower than 45°C temperature and R2 values for these temperatures were 0.9903, 0.9705 and 0.9807, respectively. As the temperature decreased, the values of Eabs and X2 increased in all bed conditions. The average value of R2 for all applied bed conditions was 0.9850. This value showed high correlation between experimental and numerical results.
Manoochehr Rashidi; Reza Amiri Chayjan; Ali Ghasemi
Abstract
Introduction: Tomato is one of the most valuable sources of minerals and vitamins supply in the human diet. Low shelf life of tomato and its short shelf life with inadequate processing facilities lead to heavy financial losses. Therefore, preserving and processing of tomato are of the commercial importance. ...
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Introduction: Tomato is one of the most valuable sources of minerals and vitamins supply in the human diet. Low shelf life of tomato and its short shelf life with inadequate processing facilities lead to heavy financial losses. Therefore, preserving and processing of tomato are of the commercial importance. Drying is one of the preferred methods for tomato preservation. Dried tomato products including half tomatoes, tomato slices and tomato powder, have many consumptions, compared with other tomato products. Among dried tomato products, tomato powder has a particular market. Powder production is an alternative method to extend the shelf life of foods. Usually the fruit powder is very dry, humidity absorber and has too much volume. Therefore, during storage, transportation and administration, it requires special care and heavy packaging which increase the cost. To overcome these problems, compression of the fruit powder in tablet form could be a proper solution. Tablet making of fruit powder has gained much popularity due to its ease of use, storage, transportation and product formulation. After the tablet making process, the pills contain high moisture contentwhich makes them un-suitable for transportation and storage. So, in order to prevent the tablets corruption and maintain their quality, tablet drying is one of the important steps after the tablet making process. The drying process is an important operation that affects the quality and final price of the product. Different drying methods play an important role in protecting foodstuffs. However, the effect of different drying methods on the quality of some foodstuffs is not clear. Materials and methods: In this research, after the preparation of fresh tomatoes, the primary moisture content of tomatoes was determined using hot air oven method. Then, using blanching method, the tomatoes were peeled and samples were cut using a sharp razor in thicknesses of 3 mm. Tomato slices were dried using a semi-industrial dryer in a hot air at 50 °C at an air speed of 1 m/s. Dried tomato slices were powdered using a grinder. In order to homogenize the particle size, the tomato powder was sieved by a 50 mesh (Cavity size 0.5 mm) sample. Suitable moisture content to create sufficient adhesion between the particles of tomato powder was selected at %23 d.b. Water and fructose were used as a bonding agent. The process of producing tomato spherical tablets was performed by a hydraulic press. Drying tests of wet compressed tablets were performed immediately after the end of the tabletting process using a hot air drying machine with microwave pre-treatment. In this study, the effect of drying variables,through using of microwave pre-treatment along with hot air, including air temperature in five levels (40, 50, 60, 70 and 80 °C), air velocity at five levels (0.5, 1, 1.5, 2, and 2.5 m/s) and the duration of microwave application at five levels (zero (without microwave), 4, 8, 12, and 16 s) on physical properties (shrinkage and unit density), mechanical (penetration resistance) and thermal (Effective moisture diffusivity and energy consuming drying) of compact pomegranate produced from tomato powder were studied. Statistical analysis of data and optimization of drying process were performed using response surface method and central composite design. Results and discussion: Results showed that effect of air temperature and duration of microwave pretreatment on all variables of compressed tomato tablets were significant in hot air dryers with microwave pre-treatment. Increasing temperature and time of microwave pre-treatment increased the effective moisture diffusivity and shrinkage of the final product. The temperature of the air inlet to the dryer had a negative effect on the resistance to penetration, the unit density and the specific energy consumption of the drying process. Drying under lower temperature conditions and less time for microwave pre-treatment resulted in an increase in the desirability of the drying process
Mohammad Kaveh; Reza Amiri Chayjan; Yousef Abbaspour-Gilandeh; Tarahom Mesri Gundoshmian
Abstract
Introduction: Eggplant (Solanum melongenaL.) is being cultivated in North America, Asia and the Mediterranean area. Its limited shelf life is one of the important restrictions in the trade of eggplant as a fresh product. Drying is one of the most current methods used to maintenance agricultural products. ...
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Introduction: Eggplant (Solanum melongenaL.) is being cultivated in North America, Asia and the Mediterranean area. Its limited shelf life is one of the important restrictions in the trade of eggplant as a fresh product. Drying is one of the most current methods used to maintenance agricultural products. This process improves the food stability, since it reduces significantly the water and microbiological activity of the material and minimizes physical and chemical changes during its storage. Dynamic modeling of drying characteristics for various agricultural products, including artificial intelligence techniques that include artificial neural networks (ANNs), particle swarm optimization (PSO) and grey wolf optimizer (GWO) Which has attracted a lot of attention recently, because the ability to learn from these systems to detect fruit and vegetable behaviors is a complex process in which mathematical models simply do not apply in recent decades. The main objective of this research was to determine the effective moisture diffusivity, and specific energy consumption of eggplant slices with a semi-industrial continuous band dryer. Moreover, some novel methods including ANN, PSO and GWO as an approximating tools were developed and evaluated for prediction of Deff and SEC of the process.
Materials and methods: Freshly harvested eggplant were purchased from a local market and stored in the refrigerator at about 4°C for experiments. The initial moisture content of eggplant was determined by oven method. About 40 g of eggplant slice (4 mm thickness) with three replicates were dried at 70°C for 24 h. Eggplant slice with average initial moisture content of 10.25% (d.b.) was chosen as the drying material.
The dryer consists of an adjustable centrifugal blower, hot air suction tube, heater, control panel, air channel to uniform distribution of hot air, drying chamber, Belt (20 cm, 200 cm), three inverters (LS, Korea), temperature and humidity sensors, electrical motor, removable upper part, base, shafts, three infrared lamps (Philips, Belgium) and belt guide. The experiments were performed at air temperatures of 45, 60, and 75C, air velocities of 1, 1.5, and 2 m/s, and belt linear speeds of 2.5, 6.5, and 10.5 mm/s. Feed and cascade forward neural networks were used in this study. There are two types of multilayer perceptron neural network. Two training algorithms including LevenbergMarquardt (LM) and Bayesian regulation (BR) back propagation algorithms were used for updating network weights. The PSO is a simple, powerful and metaheuristic technique that can be applied to solve optimization problems. In the PSO model, every solution is showed as a particle that is alike to a bird flying via the space of a potential solution. In order to mathematically model the social governance of wolves when designing Grey Wolf Optimizer (GWO), assume the fittest solution as the alpha ( ). Consequently, the second and third best solutions are named beta ( ) and delta ( ), respectively.
Results and discussion: In the present study, the application of Artificial Neural Network (ANN), particle swarm optimization (PSO) and grey wolf optimizer (GWO) for predicting the and was investigated. Based on several statistical operates [such as coefficient of correlation ( ) and mean-square error ( ), mean absolute error ( )], for predicting and was found that the GWO ( =0.9915, =0.9986, Respecively) performs better than the PSO (with =0.9927, =0.9890) and ANN (with = 0.9618, =0.9773) models. Drying behavior of eggplant slices at different air temperatures of 45, 60, and 75C, air velocities of 1, 1.5, and 2 m/s and belt linear speeds of 2.5, 6.5, and 10.5 mm/s was studied. The moisture ratio was reduced exponentially with drying time as expected. When the temperature was increased, the drying time eggplant fruit reduced. In other words, at high temperatures, the transfer of heat and mass was higher and the water loss was more excessive. Effective moisture diffusivity and specific energy consumption were calculated after drying of turnip fruit. Maximum values of for eggplant were 1.14×10-8 m2/s. The lowest amount specific energy consumption ( ) was calculated at the boundary of 130.62 MJ/kg.
