Post Harvesting Technology
Reza Tabatabaeekoloor; shaban ghavami jolandan
Abstract
Introduction: Fuel pellets are one of the uses of biomass, which are made from agricultural waste, plant residue, and animal excrement. They produce more energy per unit volume. Various factors are effective in the pelleting process. Having information about them helps to optimize the pelleting process ...
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Introduction: Fuel pellets are one of the uses of biomass, which are made from agricultural waste, plant residue, and animal excrement. They produce more energy per unit volume. Various factors are effective in the pelleting process. Having information about them helps to optimize the pelleting process and to understand the compression mechanism and the design of compacting equipment. Materials and Methods: Olive pomace raw material for making pellets was obtained from an olive processing factory in Rudbar city in Gilan province. The prepared materials were transferred to the laboratory in the necessary amount in nylon bags and dried in the oven at 105 degrees Celsius for 24 hours. The dried samples were powdered by a laboratory grinder and then passed through sieves in the range of 0.6-1.5 mm and used to make pellets. Before making pellets, the initial moisture content of the samples was obtained using the drying method. First, pre-tests were conducted to make pellets and the moldability and strength of the samples were checked. A palletization mechanism was used to compress the pellet. This system was designed and built in biosystem mechanics of Sari University of Agricultural Sciences and Natural Resources. The material was placed inside a steel mold with a cylinder inner diameter of 8.05 mm and a height of 150 mm with a blocked end. A piston with a diameter of 8 mm connected to the driving arm of the tension-compression test machine was used to compress the material. Loading by a piston with a quasi-static speed of 6 mm per minute is compressed. In this research, the effect of particle size treatments (600-900, 900-1200 and 1200-1500 μm), compaction pressure (75, 150 and 225 MPa) and temperature (50, 70 and 90 ͦC) on the density, strength and durability of the pellet were investigated.Results and Discussion: The results indicated that the main effects of all three mentioned treatments on the strength, density and durability of the pellet are significant. Also, the mutual effects of some treatments are also significant on these characteristics. The interaction effect of particle size and compaction pressure on pellet compressive strength is significant at 5% level. With the increase in particle size, the pellet strength increased first, and then with the further increase in particle size, the pellet strength decreased slightly. On the other hand, with the increase in compression pressure, the pellet resistance increased. Pellet density is an important factor for storage and transportation as well as combustion efficiency. The mutual effect of compression pressure and particle size on pellet density is significant. Changes in pellet density were obtained in the range of 1.015 to 1.350 grams per cubic centimeter. The usual and recommended density for pellets made from agricultural and forest residues should be more than 0.8 grams per cubic centimeter. The interaction effect of compaction pressure and temperature on pellet durability is significant. The range of durability changes for pellets is between 81 and 95 percent. Increasing compaction pressure significantly improved the stability of the pellets, which indicates the role of compaction in bonding between particles and creating bridges for greater particle strength. The highest pellet strength was obtained in the combination of particle size of 900-1200 micrometers, temperature of 90 degrees Celsius and compaction pressure of 225 MPa. The highest density was obtained at a particle size of 600-900 and a compression pressure of 225 MPa and the best stability at a compression pressure of 150 MPa and a temperature of 90 degrees Celsius. In general, the physical and mechanical properties of the pellet were affected by all three factors: particle size, temperature and compaction pressure.Conclusion: The results of this research showed that all three factors of particle size, compaction pressure and temperature have a significant effect on the physical and mechanical properties of pellets such as density, strength and durability. Choosing the right particle size plays an important role in making the pellet stronger. The temperature of the die during pelleting is also very important in the bonding of the pellet particles because at the right temperature, the bonding between the bridges strengthens the connection of the particles and as a result increases the strength and durability of the pellet. In general, the results of the research showed that to make pellets from olive processing factory waste, a suitable combination of particle size parameters, compaction pressure and die temperature is needed to make pellets with high strength and durability.
Post Harvesting Technology
Parham Afshari; Narges Shahgholian; Hassan Zaki Dizaji
Abstract
Introduction: Drying is one of the most economical ways to preserve food and is used to increase its shelf- life. Microencapsulation protects sensitive foods from adverse environmental conditions (such as the effect of moisture and oxygen) and reduces food quality fluctuations. The principle of microencapsulation ...
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Introduction: Drying is one of the most economical ways to preserve food and is used to increase its shelf- life. Microencapsulation protects sensitive foods from adverse environmental conditions (such as the effect of moisture and oxygen) and reduces food quality fluctuations. The principle of microencapsulation via spray drying is to prepare an emulsion or suspension and spray it in the hot air of the drying chamber. Plant pigments, such as anthocyanins, have been considered, but they are unstable under processing conditions. Hibiscus sabdariffa (sour tea) is a resistant herbaceous shrub and annual or perennial plant that contains anthocyanins. More than 300 types of sour tea are found in tropical and subtropical regions worldwide. Gum Arabic and maltodextrin are used as carrier materials to maintain the stability and functional characteristics of the powder prepared by spraying. Owing to its high solubility, low viscosity, and suitable emulsifying properties, gum Arabic is a carrier of interest in the spray drying process. Maltodextrin is a partial hydrolysis product of starch and oligosaccharides and has become one of the most important and widely used carrier compounds in spray drying because of its high solubility and low viscosity. Because anthocyanins are soluble in water, they are compatible with formulations containing maltodextrin, gum arabic, and starch. The main goal of this research was to investigate the microencapsulation of sour tea extract using a spray drying method for the development of stable anthocyanin formulations because this method is scalable.Materials and Methods: Sour tea was prepared from the gardens of Khuzestan province, Karun city, in 2023. To prepare the sour tea plant, the sepals were first washed with distilled water and dried in an oven for 15 h at a temperature of 40º C. The sepals were then powdered using a hand mill. After passing through a sieve with a mesh size of 150 micrometers, the prepared powder was extracted using 50% ethanol. The extract was passed through a paper filter and centrifuged in a refrigerated centrifuge (10 minutes, 3780 g). Extraction was performed from sour tea, and after the concentration stage, it was combined with gum arabic and maltodextrin as carriers. The carrier material including the binary solution of gum arabic and maltodextrin in a specific ratio dissolved in 1000 ml of warm distilled water (at a temperature of about 70 º C) and stirred overnight on a magnetic stirrer at 4º C were kept. The ratio of the extract to the wall material was varied (1, 2, and 3% by weight). In this study, the inlet air temperature, inlet air flow, and inlet feed temperature to the dryer were considered constant, and the inlet air was sent to the dryer at a constant temperature of 160º C. The feed and air flow rate were 70% (respectively equivalent to 3 L/min and 25 m3 /h), and the nozzle opening and closing time intervals were 3 and 1 s, respectively. In order to optimize the preparation of the powder, the response surface methodology (RMS) with a central composite design (CCD) was used to obtain a mathematical model to predict the process behavior. The effects of independent variables, including the amount of wall material (4, 7 and 10%) and sour tea extract (1, 2 and 3%), on dependent variables, such as total anthocyanin (TAC), surface anthocyanin (SAC), and encapsulation efficiency (EE), were investigated. Moisture content, solubility index, bulk density, tapped and particle density, flowability, porosity, and morphology were also investigated in the powder samples.Results and Discussion: The obtained data were modeled using the Design Expert software11. The data analysis showed that the best model for estimating the surface anthocyanin and anthocyanin encapsulation rate was the third-order model with coefficients of explanation of 0.8853 and 9205. After final optimization, the SAC value was 0.49, TAC was 4.371 mg/liter, EE was 42.27%, moisture content was 3.92, solubility index was 45.47%, bulk density was 0.98, tapped density was 1.03, and particle density was 2.28 g/cm3. Hausner and carr index confirmed the excellent flowability of the powders. The optimal wall and core materials were 66.6% and 1.63%, respectively. Scanning electron microscopy images showed that the powder particles were micrometer in size and almost spherical. Powders containing a high percentage of gum Arabic showed relatively greater shrinkage and indentation than powders containing high maltodextrin content.
Post Harvesting Technology
Mozhgan Azhdar; Narges Shahgholian; Hassan Zaki Dizaji; mansour amin
Abstract
Introduction: These days, most of the disinfectants used in the food industry such as chlorinated compounds are dangerous and harmful. Common methods of removing all types of pollution have many disadvantages for human health and the environment. It is possible to help preserve the environment and human ...
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Introduction: These days, most of the disinfectants used in the food industry such as chlorinated compounds are dangerous and harmful. Common methods of removing all types of pollution have many disadvantages for human health and the environment. It is possible to help preserve the environment and human health by replacing these methods with new ones such as ultrasound technology. Ultrasonic waves are non-thermal technology that helps increase microbial safety and prolong the shelf life of heat-sensitive foods with nutritional value and functional characteristics. Ultrasonic waves are known as one of the most effective disinfection methods for all forms of microbial and fungal contamination. These waves reduce the resistance of microorganisms by physically damaging them. Therefore, this study deals with the effect of high-power ultrasound waves on the population of two type of pathogenic microorganisms in the washing effluent of tomatoes. The selected bacteria included one type of gram-positive bacteria (Staphylococcus. aureus) and one type of gram-negative bacteria (Escherichia coli) to compare the effect of ultrasound waves on the two different types of bacteria with different cell walls. Materials and Methods: In this research, irradiation of high-power ultrasound waves were applied to the water after washing the tomatoes. In this washing effluent, the impacts of ultrasonic power (100, 300, 500 W), radiation time (300, 750, 1200 s), and water temperature (0, 30, 60 °C) were examined on the survival of the S. aureus and Ecoli. The data analysis was done for each experimental runs, using the response surface methodology (RSM), to find the best model for estimating the difference in bacterial population (CFU) before and after irradiation. Results and Discussion: The lack of fit was not significant in the analysis of variance and also the value of the explanation coefficient in the model for S. aureus and Ecoli were 0.9721% and 0.9206% respectively. This indicated the appropriate accuracy of the quadratic model in estimating the number of S. aureus and Ecoli remaining in the water after washing tomatoes (for the mentioned independent variables). Gram-negative bacteria (E coli), are composed of an inner thin peptidoglycan cell wall, surrounded by an outer lipopolysaccharide membrane. Gram-positive bacteria (S. aureus), lack an outer membrane but are made up of a multi-layered and very complex structure layers of peptidoglycan many times thicker than is found in the Gram-negatives. In general, the application of ultrasound waves causes to destruction of the mentioned bacteria. The main disinfection effect of ultrasonic waves on the population of S. aureus was power, while for Ecoli the main variable was temperature (based on the highest coefficient of quadratic equations/ 99% confidence level). Through physical, chemical and mechanical effects caused by acoustic cavitation, ultrasound is able to affect the bacterial suspension without producing a side product. The antimicrobial effect of ultrasound is achieved by a combination of chemical effects such as the production of active free radicals and thermal effects such as the production of local hot spots. The observations showed that increasing the temperature first increased and then decreased the effectiveness of ultrasound waves in the inactivation of bactetria. The negative effect of increasing temperature can be related to the decrease in the intensity of bubble explosion. Conclusion: According to the results of the experimental tests in the average time (750 s), with the simultaneous decrease in temperature (from 60 to 0 ºC) and increase in power (from 100 to 500 W), the destruction effect of ultrasound waves on S. aureus and Ecoli was increased. In the perturbation curves, the simultaneous effect of all three parameters (temperature, time and power), were investigated at the middle points (30 ºC, 750 s and 300 W). At these points, power changes were more effective in reducing S. aureus population, while temperature changes were more effective on the reduction of E coli. The population of S. aureus and E. coli decreased by increasing power of ultrasonic waves. Temperature and power had a synergistic effect, that is, the increase of both parameters led to the decrease of bacteria population. Finally, the tested variables were optimized by desirability in the RSM to minimize the population of microorganisms (S. aureus and E coli simultaneously), and parameters (in the range) obtained for the ultrasonic power, time, and temperature were 300 W, 1200 s, and 0 °C respectively.
Post Harvesting Technology
Poya kohansal makvandy; Majid Rahnama; Rasol Memar dastjerdy; Alireza Shafeinia
Abstract
Introduction Material conveying in the industries is carried out in the different ways. Pneumatic conveyors are widely used in industries. The special benefits of these conveyors have led them in the short term to widely used in different industries. Transfer of materials without dust dispersion, the ...
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Introduction Material conveying in the industries is carried out in the different ways. Pneumatic conveyors are widely used in industries. The special benefits of these conveyors have led them in the short term to widely used in different industries. Transfer of materials without dust dispersion, the flexibility to choose the vertical, horizontal or diagonal tubing, low maintenance costs and manpower, adequate safety and reliability during conveying at the high amounts of materials, easy and automatic control are the some benefits of the pneumatic conveying systems Materials and Methods The mean aperture and the coefficient of variation of sugar particles were determined by sugar crystal size distribution test. It is done based on the cumulative percentages of remaining sugar content on the sieve. The mean aperture (MA) and the coefficient of variation (CV) are obtained from the chart. 7 sieves are used for testing. The percentage of remaining sugar on each sieve was calculated. The amounts of D50% and D16% were calculated following the plotting the size of the sieves versus the cumulative percentage of the remaining sugar on each sieve graph. The conveying pressure drop includes the total pressure drop required for air alone (ΔPL), the material acceleration pressure drop (ΔPA), the friction and material collision pressure drop (ΔP*z), the pressure drop due to lifting and suspension of materials (ΔPG), and bends' pressure drop (ΔPB) in Pascal. Following determination of required power (293.42 w) to run the system, with a confidence coefficient of 3, a blower with a rated power of 700 w was selected. The amount of pressure produced by the selected centrifuge fan was measured by a pitot tube embedded in the blower outlet. The outlet air velocity was measured by a pressure gauge according to the principles of the pitot tube. Results and Discussion The treatments and their levels consisted of pipe lengths at three levels (2, 4 and 6 m), inlet air velocity at five levels (13, 16, 19, 22 and 25 m/s) and mass flow rate of sugar at three levels (160, 180 and 200 kg/h). The statistical analysis was done as a factorial based on a completely randomized design. Analysis of variance and comparison of means were done using Duncan's test at 5% level in each case. Then, the effects of the factors on pressure drop, mean aperture and coefficient of variation of particle size were investigated. Analysis of variance of data shows that the effect of conveying length, mass flow rate of sugar particles and inlet air velocity as well as their interactions and the interaction of three factors on air and sugar pressure drop is significant at 1%. In all conveying lengths, an increase in air velocity and consequently increased sugar particles' velocity at each mass flow rate causes an increase in frictional pressure drop due to the particle's collision with the wall as well as air collision with the pipe wall at each length and the sugar mass flow rate level. Also, total pressure drop has increased with mass flow rate at any velocity. Analysis of variance of data shows that the effect of conveying length, mass flow rate of sugar particles, inlet air velocity, and the interaction of mass flow rate and air velocity on qualitative properties of sugar is significant at 1% level. Considering the significance of the effects of the main factors and interactions between air velocity and mass flow rate, the effect of every main factors and the interaction of air velocity and mass flow rate on qualitative characteristics of the sample was investigated. With increasing velocity in each mass flow rate, the mean aperture and coefficient of variation significantly decreased and increased, respectively. Also, with increasing mass flow at any velocity, the mean aperture decreased and the coefficient of variation increased. By increasing the mass flow rate, the effect of the air velocity on the mean aperture reduction and increase in coefficient of variation increases, and at higher velocities, the mass flow rate effect is more pronounced. Conclusion The length of the pipe with a reduction by 15% in mean aperture and an increase of 137.5% in coefficient of variations than the initial sugar sample had the least effect on these two qualitative properties of sugar. With an increase in air velocity from 13 to 25 m/s, MA and CV values decreased by 20.27 and increased by 17.22, respectively. The velocity of 13 m/s with a reduction of 5.19% in the mean aperture and an increase of 6.69% in coefficient of variation compared to the initial sugar sample had the least effect on the size and the particle coefficient of variation size of the particles among all 5 velocity treatments. With the increase in particle mass flow rate of 160 to 200 kg/h, MA and CV values decrease by 16.49% and increase by 14.75%, respectively. The particle density increases with the mass flow rate.
Post Harvesting Technology
Shamsi Soodmand Moghaddam; Mohammad Sharifi; Hemad Zareiforoush; Hossein Mobli
Abstract
Introduction One of the medical plants is lemon verbena with the scientific name of Lippia citriodora Kunth. It belongs to the family of Verbenaceae. The essential oil of lemon verbena has different compositions, which the most important of them are Geranial, Limonene, and Neral. The most important and ...
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Introduction One of the medical plants is lemon verbena with the scientific name of Lippia citriodora Kunth. It belongs to the family of Verbenaceae. The essential oil of lemon verbena has different compositions, which the most important of them are Geranial, Limonene, and Neral. The most important and commonly used physiological method after harvesting medicinal plants is the drying of plant organs which have high energy consumption. The temperature and the method of drying of these plants affect drug quality. The aim of this study was to investigate the effect of different drying methods on essential oil extraction efficiency and the drying time of lemon verbena leaves in a continuous flow dryer system and traditional drying method. Materials and Methods An amount of 150 g of lemon verbena leaves were dried in a continuous flow dryer equipped with the solar pre-heating system at three temperatures of 30, 40, and 50 °C, and three air velocities of 1, 1.5, and 2 m/s. To determine the significant difference between the effects of different air velocities and air temperatures in the dryer method, a factorial experiment was used in a completely randomized design with three replications for each treatment. The required heat for product drying was supplied by the combination of a gas water heater and a solar water heater. In the first stage, the gas water heater was off and the required thermal energy was provided only by the solar water heater. The radiation of solar energy heated the water in the solar water heater tank. After the water temperature reached the desired level, warm water was entered into the heat exchanger through an electric valve and a water pump. The air flow generated by the centrifugal blower was passed through the heat exchanger, and it was heated by the warm water. The warm air was then entered into the drying chamber through the air inlet pipe. If the temperature of the water in the solar water heater tank was lower than the desired level, the electric valve was actuated and made to direct the water flow to the inlet of the gas water heater before entering the water into the heat exchanger. At the same time, the gas water heater was turned on and provided the required thermal energy for warming up the water. In order to compare the quality of the dried product with the traditional drying method, 30 g of dried leaves from each treatment were submitted to hydrodistillation with a Clevenger-type apparatus and extracted with 450 ml of water for 3 h. A completely randomized design was used to determine the significant difference between the essential oil extraction efficiency of each method. Data were analyzed in SAS (Version 9.00) Software and the mean comparison was performed using Duncan's multiple range test. Results and Discussion The results showed that with increasing the air temperature and air velocity, the drying time of lemon verbena in the dryer significantly decreased. Also, with increasing airspeed to the dryer, moisture transfer from the product was performed faster. Finally, the drying time of the product was reduced. The highest essential oil extraction efficiency was obtained at 40 °C and 2 m/s (0.61%), while the lowest essential oil extraction efficiency was 0.23% in the sun drying method. The minimum drying time was obtained at 50 °C and the air velocity of 2 m/s in the dryer (110 min) and the maximum drying time was obtained in the (shade) traditional method (720 min). In this research, a new system was introduced in order to increase the uniformity and quality of the product in the process of drying the lemon verbena. In addition, by comparing the quality of dried product with traditional methods, it was found that the essential oil extraction efficiency in this dryer system was significantly (at 1% level) more than traditional drying methods. Also, the drying time in this system is much shorter than traditional drying methods. Conclusion In general, the results indicate that the drying methods in this study have a significant effect on the essential oil extraction efficiency and drying time of lemon verbena leaves. According to the results of this study, the use of this system for drying lemon verbena has advantages, such as increasing the quality of the product and reducing the drying time compared with the traditional methods. The most important advantages of using this system include: providing a considerable part of the required energy free, the use of warm water in a circulated circuit and the adaptation of the solar pre-heating system to the environmental objectives, the uniformity of product drying due to the continuous flow drying system, shorter drying time and the better quality of the product than traditional drying.
Post Harvesting Technology
Mohammad Momeni Arani; Abbas Rezaei Asl; Azim Ghasemnezhad
Abstract
Introduction Drying is one of the important stages after harvesting of plants and agricultural products, which plays an important role in the quantity and quality of the active ingredients. The purpose of drying is to reduce water to a certain level for low and stop the microbial activity. Therefore, ...
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Introduction Drying is one of the important stages after harvesting of plants and agricultural products, which plays an important role in the quantity and quality of the active ingredients. The purpose of drying is to reduce water to a certain level for low and stop the microbial activity. Therefore, in laboratories the effects of different levels of temperature and time are investigated on different plant properties during drying operations with laboratory dryers and ovens. It can be said that the principled and thorough drying of medicinal plants is necessary in order to reduce moisture, increase the shelf-life and increase the quantity and quality of the active ingredients. Today, many control algorithms are used to control temperature, which is much more efficient than the on-off. Fuzzy control is suitable for fast control and high accuracy of proper nonlinear processes. Likewise, the type of ventilation and the placement of thermal elements are also very influential on the heating system and the temperature of the chamber. Today as foreign companies, in addition to focusing on the type of control system and intelligence ovens, many studies have been done on how the element is placed, on its type, the shape of the fan, its type, and the design of the air channels. Materials and Methods The dryer was designed with software Solid Works and constructed in manufacturing workshop of the Bio-System Mechanics Engineering Department of the Natural Resources and the Agricultural Sciences University of Gorgan, Iran. The device has a fuzzy control system, a ventilation, and fan system. The built-in dryer has two mechanical and electrical parts. This dryer has an external chamber with dimensions of 74 × 50 × 60 cm and internal chamber dimensions of 40 × 35 × 50 cm. The device was insulated with thermal spray foam. The electronic circuit was designed using Proteus simulation software and implemented on the board. The main piece of information processing and controlling the algorithm in the dryer control system is the microcontroller. The microcontroller programming was written by C software and transmitted to the microcontroller with the Code Vision software. The tests were performed at three levels of 60, 80, 90 °C. The programmability of the device was also evaluated simultaneously for four different temperatures and times. The device was evaluated at 4 levels of 90, 70, 50 and 30 °C and four levels of the time were done respectively 10, 10, 10, and 20 min. Also, in the process of increasing temperature, the temperatures of 40, 60, 80 and 90 °C respectively were tested. Also, the stability function and the time to reach the temperature were compared with two samples of the laboratory dryer (oven) imported Memmert and Bender models which had a fuzzy control system and a ventilation system and a built-in oven model in the interior. Results and Discussion Because exactly as wasted, the temperature of the chamber walls is applied to the chamber, the device is capable of maintaining the temperature of the chamber at the set point. The result of the evaluation in the energy waste from the wall of the device showed that after about 200 min, the temperature of the internal chamber (which was at 80 ° C) was equal to the outside temperature of the chamber. The results showed that during temperature stability, the difference in temperature between different points of the compartment (places where laboratory samples are placed) is less than ±0.5. The programmability of the device was evaluated at 4 levels of 90, 70, 50 and 30 °C; after reaching the temperature of 90 °C, and at the end of the scheduled time, the temperature is reduced to a minimum, reaching the next temperature. Reducing the temperature for other temperatures was also done according to the program. The results of the programmability of the device were shown in the incremental step of the temperature; in the incremental process, as the temperature decreases, the temperature difference between the points is very small and reaches the temperature stability as soon as it reaches the regulated temperature. The control system used can properly maintain the temperature in a stable state. The results of the comparison of the performance of the dryer control system made with other experimental dryers at a temperature of 80 ° C showed that the dryer was able to stabilize the inside of the compartment at the desired point, in comparison with other ovens. The built-in dryer function is compatible with the Memmert UFE500 and the Binder FE53 ovens. Due to the cost of the device, its use will be very useful for conducting research in research centers. Conclusion The fuzzy control system used in the dryer was able to properly control the temperature of the chamber according to the program. The control system of the device was able to control the temperature of the chamber at a regulated point with a minimum temperature variation (less than half a °C). The built-in dryer was able to reduce and increase the temperature step by step in a given temperature range according to the given program. The performance of the dryer, compared with other ovens, showed that it could match the best of imported ovens.
Post Harvesting Technology
Mohammad Rasool Afifi; Yaghoob Mansoori; hassan zaki dizaji; Gholamreza Akbarizadeh
Abstract
Introduction Date fruit is a strategic horticultural product in the Middle East that plays an important role as an economic product to develop exports. Iran is the second world producer that contains 14% production of date fruit in the world and has a high potential in order to ideally exploit this valuable ...
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Introduction Date fruit is a strategic horticultural product in the Middle East that plays an important role as an economic product to develop exports. Iran is the second world producer that contains 14% production of date fruit in the world and has a high potential in order to ideally exploit this valuable product. Condidering the low price of Iran's exported dates due to poor preparation and packaging process it is necessary to use new technologies for classification and grading of them. The application of machine vision in agriculture has increased considerably in recent years.There are many fields in which computer vision is involved in order to develop precision agriculture. Machine vision systems by elimination of manual inspection in the field of postharvest technologies improve accurate and uniform quality control of agricultural products. In most of these applications, the method of image analysis for product categories, with the determination of some external features such as color, size, shape, and surface texture has been used (Blasco et al., 2012). Alohali used RGB images taken from Date fruits and defined a set of qualitative external features of dates and categorized them into three categories in terms of quality. One of the characteristics of the soft tissue was detected using color intensity distribution. The final precision of carefully designed system using a propagation neural network was 80% (Alohali, 2011). The size is a particular aspect of external appearance of fruits and vegetables; the price of agricultural products is usually related with their size; therefore, grading of fruits and vegetables into different size groups of size is always necessary in the postharvest handling and processing stages (Zhang et al., 2014). Texture is the other significant sensory quality attribute that has been frequently used in the external quality inspecting and grading systems for the agricultural product quality evaluation. Texture is closely related to some internal quality of fruits and vegetables, such as maturity and sugar content. Therefore, texture is one of the widely used indicators the consumer uses for quality assessment of fruits and vegetables. Texture analysis can also play an important role in defect recognition and segmentation in grading systems due to its powerful discriminating ability (Lee et al. 2008). Materials and Methods The current study examined image processing technology for grading Zahedi cultivar dates in Khuzestan province. Each date fruit was placed under the camera and imaged. At the same time, the samples were classified by an experienced grader. Imaging was conducted in a lighting box to avoid the effects of ambient light. Capturing images was done by a digital camera using CCD sensor. External features of dates such as color, size, shape and surface texture were extracted by image processing methods using MATLAB software (Version R2013a, The Mathworks Inc., Natick, MA, USA). Eleven size and shape features, nine color features, and six external texture features were extracted. The features which led to better separablity for classification were selected using stepwise discriminant analysis (SDA). Selecting the best features is effective to increase accuracy and speed of the algorithm. Two methods of learning machine were used for final classification: discriminant analysis that is a statistical technique and neural networks (ANN). Discriminant analysis method and Neural networks were implemented in SPSS 22.0 and neurosolution 7.0 software respectively. Results and Discussion The best channel to separate dates from background was identified by comparison of the histogram of 9 channels from RGB, HSI and Lab color spaces. The histogram graph, which has more breakdown in the range of intensities, is more suitable to apply thresholding operation because it has a good contrast with the background. Channel B from RGB color space was chosen to segment dates from background. Channel of B has a better contrast between the color channels and also its corresponding histogram intensity values led to the best separability. Five features of size and shape, three features of color and three features of external texture were selected by SDA method to reduce dimension of features space. Degrees marked from 1 to 3 for qualitative grading and sorting by size define levels of quality and determine size from big to small dates respectively. According to table 4, accuracy of classifications for grading, sorting by size and inspection of wrinkled date fruits from healthy ones were 93.6%, 94.4% and 90% respectively. Classifications by MLP neural networks were done. The most important factor for evaluation of neural networks is Correct classification rate (CCR%). The results based on CCR from Confusion matrix is reported in table 5. Accuracy of classifications for grading, sorting by size and inspection of wrinkled date fruits from healthy ones using ANN were 95.7%, 92.3% and 93.8% respectively. Conclusion Final accuracy of classification using discriminant analysis and neural network was achieved 92.7% and 93.9% respectively. Results show relative superiority of neural networks over statistical methods due to its accuracy. According to high accuracy of classification using learning machine methods, it can be concluded that using image processing algorithm was successful in extracting external features for sorting and grading of dates.
Post Harvesting Technology
Armin Ziaratban; M Azadbakht; Azim Ghasemnezhad
Abstract
Background and objective Unlike engineering materials, apples are living tissues which survive after harvesting. Thus, post-harvest processes such as transporting and packaging should be carried out in a way that makes them less vulnerable. Among the agricultural products, fruits and vegetables are the ...
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Background and objective Unlike engineering materials, apples are living tissues which survive after harvesting. Thus, post-harvest processes such as transporting and packaging should be carried out in a way that makes them less vulnerable. Among the agricultural products, fruits and vegetables are the commodities that due to their low resistance to the shell and high humidity, have a high sensitivity against mechanical damages that occur when processing them. In order to minimize waste, proper post-harvest management and convenient techniques for transport and storage are required. Mechanical damages can occur in three major ways, including pressure, impact, and abrasion. The pressure during the harvest may impose on the fruits by pickers or occur when fruits are stored in the bottom of the box. External damages may happen due to the weight of picked apples in the baskets in deep boxes or when transporting the boxes by hooks. In fruit packaging stations, pressure, impact, and vibration can occur when packaging of fruits in boxes, as well as the washing and waxing fruits. Pressure forces usually happen during transport and storage of the fruit. This study was undertaken to study the impact on sugar, phenol, acidity and fatigue area that play a major role in the final quality of the product. Materials and methods Static and dynamic impacts and storage time were considered as the independent factors in this study and their effects were analyzed on the chemical parameters including sugar, phenol, acidity and fatigue area. The static impact was conducted by Instron Sntam with three loading speed 5, 7, and 10 mm/min for 1min. The dynamic impact was conducted by a pendulum that simulated the energy applied to apples that dropped. The amount of energy was equivalent to 2.25, 3 and 3.75 J. Apples that underwent impacts, were kept for 20, 40 and 60 days to measure the impact on changes of chemical parameters and determine the area of fatigue. After each storage period, the samples were photographed. The area of fatigue was measured using image processing techniques and Image J software. The image processing consists of two parts: hardware and software. The hardware of computers, cameras and imaging chamber is formed. The camera was connected by cable to a computer and the images were stored on a computer's permanent memory. Used computers used running windows seven, five-core central processing unit, and RAM was 4 Giga bytes. Computer is the processing of the data and the image acquisition step to the final step, the output data is the most important role. The used camera was a Canon, made in Japan, was mounted vertically inside the box. Shooting box was used just because all the photos must be taken in a constant condition of light regarding light intensity of surroundings and distance of apples from the camera. The Chamber was made of wood and shaped like a cube with dimensions of 45 × 45 × 45 cm, which is just an open area. Three eight-watt fluorescent lamps for lighting inside the box was fixed to the ceiling box around the triangle mounted camera. Image J analyzer is a powerful software with various uses. This software can calculate the area and pixel value statistics of user-selected portions of the image. Factorial experiments were carried out in a completely randomized design with three replications. Results Results revealed that acidity changes and fatigue area during the storage under static and dynamic impacts were significant at 0.01 and 0.05% and for phenol and sugar were significant at 1 and 5%. Also, in this test, sugar content and acidity were generally reduced over time, and phenol and fatigue area increased. Conclusion In order to avoid excessive reduction in sugar and fruit quality, maintenance time should be reduced as much as possible. Phenol increased during storage, after applying impact; its oxidation when contacting air results in toxic compounds that are harmful to humans. Therefore, packaging using the pads and increasing the quality of the harvesting and transporting is necessary in order to reduce the damages to the fruit. Fruit acidity during storage after the impacts showed the significant changes that could negatively affect the taste of the fruit and as a result, its marketability.