Research Article
Precision Farming
M. Naderi-Boldaji; M. Tohidi; M. Ghasemi-Varnamkhasti
Abstract
IntroductionThe development of portable devices for real-time quality assessment of sugarcane is an essential necessity in the agricultural and industrial technology of sugarcane production and processing. Attributes of sugarcane such as sugar concentration and water content can be utilized for this ...
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IntroductionThe development of portable devices for real-time quality assessment of sugarcane is an essential necessity in the agricultural and industrial technology of sugarcane production and processing. Attributes of sugarcane such as sugar concentration and water content can be utilized for this purpose. Near infrared (NIR) spectroscopy has been one of the most widely applied techniques for quality evaluation of sugarcane. However, NIR spectrophotometers in the full NIR wavelength range (up to 2500 nm) are expensive devices that are not readily available for portable applications. Short-wave NIR devices in the range of 1100 nm are available at lower costs but need to be evaluated for specific applications. On the other hand, dielectric spectroscopy has attracted the attention of researchers for quality evaluation of agricultural and food products. In a previous study, a parallel-plate capacitance sensor was developed and evaluated for non-destructive measurement of sugarcane Brix (total soluble solids) and Pol (sucrose concentration) as well as water content, in the frequency range of 0-10 MHz. The results showed excellent prediction models with root mean square errors smaller than 0.3 for Brix and Pol. This study aimed to develop and evaluate a dielectric sensor that can be extended for portable measurements on standing sugarcane stalk in comparison with short-wave NIR (SWNIR) spectroscopy to address how the fusion of the two methods may improve the accuracy of models for predicting sugarcane Brix.Materials and MethodsA dielectric sensor in the form of a gadget was developed with metallic electrodes to encompass the sugarcane stalk samples. The dielectric sensor was excited with a sinusoidal voltage within 0-150 MHz frequency range by a function generator, and the conductive power through the electrodes was measured using a spectrum analyzer. 105 sugarcane stalk samples were prepared from seven sugarcane varieties and scanned with the dielectric sensor. The samples were also subjected to Vis-SWNIR radiation in the wavelength range of 400-1100 nm, and the reflectance spectra were captured. Reference Brix and water content of the samples were determined using a portable refractometer and oven-drying method, respectively. Regression analyses and artificial neural networks were performed on independent and combined data from dielectric and Vis-SWNIR spectroscopy to develop prediction models for Brix and water content.Results and DiscussionPartial least squares regression on independent data sets of each instrument resulted in RMSEP = 1.14 and RMSEP = 1.88 for Brix using Vis-SWNIR and dielectric spectroscopy, respectively. Moreover, data fusion of dielectric and Vis-SWNIR spectroscopy at a low level for the prediction of Brix significantly improved the prediction accuracy to R2P = 0.94 and RMSEP= 0.74. The medium-level data fusion resulted in R2P = 0.89 and RMSEP = 0.93 for prediction of water content.ConclusionIn this study, the accuracy of using Vis-SWNIR and dielectric spectroscopy data for predicting Brix and water content in sugarcane stalk samples was evaluated. To develop the prediction models, partial least squares (PLS) regression and artificial neural network (ANN) were compared. First, the prediction models were developed based on Vis-SWNIR and dielectric spectroscopy independently. Then, the two techniques were fused and the improvement in the prediction accuracy was investigated. Fusing the two methods at an intermediate level lowered the RMSE of Brix to 0.74, showing noticeable improvement compared to previous studies. Based on the achieved results, developing a fusion probe for SWNIR and dielectric spectroscopy and designing the measuring system could be the aim of future studies for in-situ evaluation of sugarcane quality parameters. Due to the importance of sugarcane quality evaluation, during growth and maturity, the results of this study can have a significant role in the development of a portable device that combines NIR and dielectric spectroscopy methods for fast and non-destructive evaluation of sugarcane quality parameters.AcknowledgmentThis article was extracted from a research project financially supported by the Research deputy of Shahrekord University. The grant number was 0GRD34M1614. The authors would like to appreciate the support of the Amir-Kabir Sugarcane Agro-Industry Co., Khuzestan, Iran for providing the sugarcane stalk samples.
Research Article
Modeling
M. Almaei; S. M. Nassiri; M. A. Nematollahi; D. Zare; M. Khorram
Abstract
IntroductionDrying shrimp is one of the storage methods that, while increasing the shelf life, leads to the production of a versatile product with various uses, from consumption as snacks to use as one of the main components of foods. Drying is preferred over other preservation methods because it offers ...
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IntroductionDrying shrimp is one of the storage methods that, while increasing the shelf life, leads to the production of a versatile product with various uses, from consumption as snacks to use as one of the main components of foods. Drying is preferred over other preservation methods because it offers numerous advantages, including extended shelf life, enhanced microbial stability, convenient consumption, reduced transportation costs, increased value, and product diversity.To accurately model these processes and thus obtain information on factors such as shelf life and energy consumption, it is necessary to determine the product’s initial and final temperatures, its geometry and dimensions, and its thermo-physical characteristics. Simulation of different drying processes requires accurate estimation of the effective moisture diffusion coefficient, which is highly dependent on temperature and humidity. Its dependence can be shown by an equation with an Arrhenius structure as an empirical function of humidity and temperature, or by considering the activation energy.It is necessary to have sufficient knowledge about heat and mass transfer characteristics, such as diffusion or penetration coefficient and the heat transfer coefficient to estimate the final temperature and drying time. This study investigated the drying process of peeled farmed shrimp (Litopenaeus vannamei) using a convective hot air dryer. Various parameters such as shrinkage and the effective moisture diffusion coefficient were examined.Materials and MethodsA drying device was built to conduct experimental studies on drying shrimp samples. The experiments were conducted on sliced shrimp meat samples at temperatures of 40, 50, and 60 degrees Celsius, with a constant air velocity of 1.5 m/s. The experimental drying models were based on diffusion theory. In these models, it is assumed that the resistance to moisture diffusion occurs from the outer layer of the food. In most cases, Fick's second law was used to describe the phenomenon of moisture penetration.The study used the standard method of immersion in toluene to measure volume changes in the samples. During the drying process, the volume of the samples was measured at 45-minute intervals, and their volume changes were calculated. To measure the moisture content of the samples, each test started by recording the initial weight of the samples using a digital scale with an accuracy of ±0.001 g. During the drying process, the samples were weighed each time their volume was measured.Shrinkage during the drying process is commonly modeled by finding a relationship between shrinkage and moisture, using linear and non-linear models. In most cases, effective permeability is defined as a function of humidity and temperature. For this purpose, curve-fitting methods were employed to analyze the data collected from experimental tests. The appropriate function was extracted by incorporating the Arrhenius equation, which is applicable to most food items.Results and DiscussionBased on the results of statistical indices, the linear model was the best model for depicting the relationship between shrinkage changes versus moisture ratio changes among the various experimental models evaluated for shrinkage and drying kinetics. Similarly, the Weibull distribution demonstrated superior performance in expressing variations in moisture ratio over time. A moisture dependent experimental model was used to express the variations in the apparent density of shrimp, resulting in a computed range of 1017-1117 kg m-3. Furthermore, an Arrhenius equation was derived to express the effect of moisture content and temperature on the effective diffusion coefficient of shrimp. According to the results, the effective diffusion coefficient of shrimp exhibited variations ranging from 0.08 ×10-9 m2 s-1 to 7.39×10-9 m2 s-1. When deriving the effective diffusion coefficient, the impact of the number of terms in Fick's second law on the variation of the moisture ratio was studied. The findings revealed that increasing the number of terms beyond 100 did not significantly affect the model’s outputs.ConclusionThe linear model had the highest coefficient of determination (R2) among the evaluated shrinkage models, as well as the lowest root mean square error and sum of square error (SSE). This makes it the most optimal model for interpreting shrinkage at the tested temperature levels. The Weibull distribution experimental model proved to be the most suitable for expressing changes in the moisture ratio of shrimp meat slices over time within the evaluated temperature range. The Arrhenius model accurately predicts changes in the effective diffusion coefficient of shrimp slices with respect to temperature and moisture content within the tested temperature range.
Research Article
Agricultural waste management
F. Mortazavi; R. Khodabakhshian; M. Moeenfard
Abstract
IntroductionTannins are a type of phenolic compound usually found in plants, with high molecular weights typically ranging from 500 to more than 3000 Da and even up to 20000 Da. The chemical structure of tannins is very diverse and varied. Tannin exists in plant cells in two forms: hydrolyzable and condensed. ...
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IntroductionTannins are a type of phenolic compound usually found in plants, with high molecular weights typically ranging from 500 to more than 3000 Da and even up to 20000 Da. The chemical structure of tannins is very diverse and varied. Tannin exists in plant cells in two forms: hydrolyzable and condensed. The tannin content in plants can vary from 0.2% to 25% of the dry weight of the plant. This can vary depending on the plant species, harvest time, plant habitat, and extraction method. Currently, tannin is used in various fields such as leather making, medicine, food, beverages, ink and glue making, paint and tanning industries, plastic resins, water treatment, and surface coatings. The application of tannins depends on the tannin concentration. Extraction of tannin from agricultural products is done by different methods. Maceration, decoction, pressurized water extraction, Soxhlet extraction, supercritical fluid extraction, ultrasound, and microwave are among these methods. Ultrasound extraction is an effective method for extracting chemical compounds, which is performed in a shorter period of time compared to other methods, and can be used for heat-sensitive compounds such as tannins.Materials and MethodsPotato peels were randomly selected, dried, and ground. Extraction was performed with an ultrasonic device, and after centrifugation, the total amount of phenolic compounds was measured using the Folin-Ciocalteu method. Afterward, utilizing the method used by Makkar et al. (2001), the amount of total tannins was calculated, and the condensed tannin content was calculated using the method introduced by Porter et al. (1986).Results and DiscussionThe average amount of total tannin extracted by using water as solvent was 142.8 ± 50.9 mg per 100 grams of dry powder in a period of 15 minutes, which was the highest amount of extraction. After water, methanol was the second solvent, yielding an extracted amount of 0.63 ± 55.9 mg per 100 grams of dry powder in 15 minutes. The lowest amount of extraction was related to the ethanol solvent in which was measured over a period of 10 minutes.Due to its higher polarity, water is the best-performing solvent for extraction. Comparing the results of this experiment with previous research, water is suitable for extracting tannins from potato peels. Additionally, water is a non-toxic and environmentally friendly solvent, and making it an ideal choice for extraction. Increasing the extraction time from 10 to 15 minutes, significantly affects the total amount of extracted tannin, more tannin being extracted during the longer the extraction period.The effect of extraction time on the amount of condensed tannin is not significant, and no variable in this study had a significant effect on the amount of extracted condensed tannin. It is expected that the increase in the total amount of tannin with the increase in extraction time is related to the increase in the amount of hydrolyzable tannin extracted from the sample.ConclusionIn this research, the amount of tannin extracted from potato peel was measured. The ultrasound method was used to prepare potato peel, which is a less expensive and faster alternative to other methods. The effect of different solvents were investigated over various extraction times. The results showed that the total amount of extracted tannin increases with the ultrasound extraction time, specifically from 10 to 15 minutes. However, with the increased extraction time, the amount of condensed tannin does not significantly increase. Among the studied solvents, water accounted for the highest amount of extracted tannin. After water, methanol was the second-best solvent, followed by acetone and ethanol. Water is an effective and environmentally friendly solvent for tannin extraction. Potato peels are rich in tannin and contain significantly less condensed tannin than hydrolyzable tannin.
Research Article
Nanotechnology (packaging films, biocomposites, solar cells)
N. Tajari; H. Sadrnia; F. Hosseini
Abstract
IntroductionPolylactic acid (PLA) is a biodegradable polymer that can replace petroleum-based materials in packaging films due to its unique properties. However, sometimes the degradability of polymers can be considered a negative factor, such as when significant changes in the mechanical properties ...
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IntroductionPolylactic acid (PLA) is a biodegradable polymer that can replace petroleum-based materials in packaging films due to its unique properties. However, sometimes the degradability of polymers can be considered a negative factor, such as when significant changes in the mechanical properties of the polymer occur during use. Another notable issue is the brittleness of polylactic acid, which can be modified to some extent by adding other materials. The addition of materials such as nanoparticles and plasticizers can improve the flexibility and mechanical properties of polymer films. Polymer films must possess acceptable physical, mechanical, thermal, and other relevant characteristics for use in the packaging industry. The acceptable level of these properties can be obtained by comparing them with the established standards for commonly used polymers in the industry. Low density polyethylene (LDPE) is a polymer widely used in the packaging industry, making it a good benchmark for comparison. This research focused on studying various factors affecting the quality of the produced films, including mechanical properties, light absorption, contact angle, and microstructures. Investigating the mechanical properties of the PLA films is crucial due to the polymer’s degradability over time. Polylactic acid films with different compounds containing PEG 400 and Tween 80 as plasticizers and ZnO nanoparticles were investigated for 14 months (in the first, second, third, fourth, and fourteenth months) in terms of mechanical properties. Finally, the obtained values were compared with standard values for packaging and their mechanical behavior was analyzed.Materials and MethodsExperiments were performed in the post-harvest and central laboratories of Ferdowsi University of Mashhad, Iran. The films were prepared using the solvent casting method. First, PLA granules were dried for 24 hours at 60 °C and then 1 g of PLA in 50 ml of dichloromethane was dissolved at room temperature by magnetic stirring for 12 hours. ZnO nanoparticles, PEG 400 and Tween 80 were incorporated into PLA and DCM solution, 1 wt% PLA, 20 wt% PLA, and 0.25 wt% solution, respectively. To prepare films containing nanoparticles, nanoparticles and dichloromethane were sonicated with an ultrasonic probe for 10 minutes and then added to the base solution and stirred for one hour.Mechanical properties of the samples were determined based on the ASTM D882-02 standard method. A texture analyzer (H5 KS, Manchester, U.K.) was used for this test. Light absorption was studied using a spectrophotometer (CAMSPECM550, UK). The contact angle of the samples was measured using a goniometer (model 200-00, Ramé-Hart Instrument Co, Succasunna, USA) in accordance with the ASTM D5946-04 standard. The surface morphology of the samples was visualized using scanning electron microscope (LMU TESCAN BRNO-Mira3, Czech Republic). The results were analyzed using Minitab software version 18 (Minitab Inc, USA) and the graphs were created in Microsoft Excel 2013.Results and DiscussionThe neat PLA film has a smooth surface, and with the addition of nanoparticles or plasticizers, the surfaces become uneven. The addition of nanoparticles and plasticizers caused more opacity of the film and better protection against ultraviolet rays. The presence of plasticizers, especially Tween 80, increased the hydrophilicity of the films. Packaging films should be flexible and have ductile behavior and the addition of plasticizers caused ductile behavior. However, Tween 80 was not able to create stable ductile behavior. The stress-strain diagram shows that most samples displayed ductile behavior over 14 months, except for the neat PLA film and the film containing Tween 80 and nanoparticles. The values of tensile strength, elastic modulus, and elongation at break for low density polyethylene have been reported as 11.7 MPa, 260.4 MPa, and 225%, respectively. The lowest value of tensile strength (18.56 MPa) and elastic modulus (1114.68 MPa) were related to P400/T80 film. This difference shows the acceptability of polylactic acid in the packaging industry. The elongation value is much lower than the standard, indicating the need to modify this parameter.ConclusionThe research findings revealed a significant effect of film type on mechanical properties, as well as a remarkable impact of storage time on tensile strength and elongation at break. The effect of various factors such as changes in the texture of the film due to the presence of plasticizers or non-uniform distribution of nanoparticles makes it impossible to determine a consistent trend for the effect of time on the films. The elongation at break for the produced films was much lower than the standard, which still needs to be modified due to the importance and sensitivity of this parameter in packaging. Polylactic acid has high tensile strength and high elastic modulus. Therefore, it can be combined with other polymers, various plasticizers, or nanoparticles at higher percentage to improve flexibility. The presence of plasticizers and nanoparticles in the film substrate increased opacity and enhanced protection against ultraviolet rays. The produced films were more hydrophilic compared to low density polyethylene.Acknowledgment This research was supported by Ferdowsi University of Mashhad (Grant No. 54096). The authors would like to thank Dr. Mohammadreza Pajohi-Alamoti, Department of Food Hygiene and Quality Control, Bu-Ali Sina University, Hamedan, Iran for providing polylactic acid granules.
Research Article
Agricultural systems engineering (greenhouse, fish farming, mushroom production)
M. Zangeneh; N. Banaeian
Abstract
IntroductionAgricultural mechanization plays a crucial role in driving agricultural development and is considered one of the most capital-intensive inputs in the agricultural sector. Effective supply chain management is a crucial necessity for improving the quality of agricultural machinery and reducing ...
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IntroductionAgricultural mechanization plays a crucial role in driving agricultural development and is considered one of the most capital-intensive inputs in the agricultural sector. Effective supply chain management is a crucial necessity for improving the quality of agricultural machinery and reducing operational expenses in agricultural mechanization. This is imperative for the advancement of agricultural mechanization. The present research aims to identify the primary structures of the supply chain for rice agricultural machinery in the provinces of Gilan and Mazandaran in Iran. The study also examined the important functional aspects of the chain members, including manufacturers, importers, retailers, and farmers who serve as the ultimate consumers of the chain's products. Furthermore, the research delved into the processes that govern the supply chain.Materials and MethodsMeasuring supply chain performance involves utilizing the Supply Chain Operations Reference model (SCOR) with five distinct dimensions: cost (12 questions), responsiveness (22 questions), flexibility (16 questions), assets (13 questions), and reliability (30 questions). The study data were analyzed using SPSS software. Additionally, latent variables were generated at each level of the hierarchy by using the variables from the aforementioned model. The normality of the variables was assessed using the Kolmogorov-Smirnov test. The evaluation of normal variables was conducted through a one-sample t-test, while abnormal variables were evaluated with a one-sample Wilcoxon test. Furthermore, descriptive analysis of the expectations and constraints of manufacturers and importers regarding rice machines was carried out.Results and DiscussionThe Wilcoxon test results indicate the impact of commitment, cost management, and communication on the average test value. The variables of normal distribution such as human resource management, quality management, strategic organization, flexibility, responsiveness, performance, and reliability in stores, exhibit significant deviation from the mean value. The majority of store managers and agricultural rice machinery dealers lack formal education in the field of agricultural machinery. Including individuals with educational backgrounds in agricultural machinery at various stages of the supply chain will likely improve the dissemination of information throughout the chain. Employing dependable techniques for transmitting accurate information regarding consumers' quality requirements can assist suppliers in manufacturing or importing superior-quality machinery. This approach not only minimizes uncertainty in the supply chain and streamlines inventory management but also reduces the lead time for meeting consumer demands.ConclusionThe continuous demand for rice agricultural machinery in Iran has resulted in the bullwhip effect phenomenon being perceived as a less significant challenge in the supply chain. Currently, local manufacturing enterprises have relatively limited knowledge regarding the market and technical needs of rice farmers compared to their foreign counterparts. It is advisable for manufacturing companies to broaden their comprehension of consumer behavior and needs by diversifying their market evaluation techniques.
Research Article
Modeling
M. Sadeghi-Delooee; R. Alimardani; H. Mousazadeh
Abstract
IntroductionThere are two types of hydropower harvesting methods: conventional and unconventional. In the conventional method, the potential energy of water is harvested using a dam or barrage. However, in the unconventional method, the kinetic energy of flowing water is extracted using hydrokinetic ...
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IntroductionThere are two types of hydropower harvesting methods: conventional and unconventional. In the conventional method, the potential energy of water is harvested using a dam or barrage. However, in the unconventional method, the kinetic energy of flowing water is extracted using hydrokinetic turbines. Resource assessment is a pivotal step in developing hydrokinetic energy sites. Power density (power per unit area) is used to estimate the theoretical hydrokinetic power of a site. Flow velocity and cross-sectional area are the two variables that constitute the power density. Researchers use various methods such as numerical simulation, direct velocity measurement, or indirect velocity calculation using discharge data to conduct resource assessment. In the latter method, the Manning equation is used to convert the discharge data into velocity values. While this method is straightforward for canals, given their fixed and known geometry, it is cumbersome to calculate the hydraulic radius in rivers. To overcome this challenge, numerous researchers have proposed the utilization of hydraulic geometry (HG) to estimate the width and depth of a river reach, and then calculate the hydraulic radius based on these estimated values. The main objective of this study is to present and implement a fast method for assessing theoretical hydrokinetic power using the HG and the Manning equation.Materials and MethodsIn the present study, two hydrometry stations (Gachsar and Siera-Karaj) were selected in the Karaj dam watershed in Iran to implement resource assessment based on HG. A computer code comprising the following four steps was developed in Python using the Google COLAB environment.Data Preparation: The monthly-averaged discharge, Manning roughness coefficient, and slope were collected and imported into the code. The roughness coefficient could be determined directly or indirectly. In the present study, it was considered to be 0.045 for the Karaj River according to the literature review. ArcGIS software and the Digital Elevation Model (DEM) were used to extract the local slope of each hydrometry station. For this purpose, the stream network of Alborz province was first extracted, and then the longitudinal elevation profile was measured using the 3D Analyst tools. Discharge Data Processing: The flow duration curve (FDC) is one of the computational tools used by engineers to describe the hydrological regime of watersheds. FDC is a graphical representation of the cumulative distribution of flows. In the present study, an all-time record FDC for each station was constructed, and fitted with five different probability distribution functions (PDF). The results of PDF fittings were evaluated by different goodness-of-fit indices, and the best PDF was selected. Calculations of HG and the Manning Equation: The HG formulas were used to calculate the width and depth of flow using the reconstructed FDC from the previous step. These values, along with the roughness coefficient and slope, were used to calculate flow velocity using the Manning equation. After obtaining the flow velocity values, the power density was easily computed. Generating Outputs: In the final step, two categories of outputs are generated: (1) duration curves for width, depth, flow velocity, and power density, and (2) theoretical and turbine-extracted energy diagrams.Results and DiscussionThe goodness-of-fit indices for PDF fitting indicated that the log-normal PDF is the most suitable distribution to describe the FDC with a coefficient of determination of 0.99. The calculated average discharge (Q50) for the Gachsar and Siera stations was 2.34 and 7.68 m3s-1, respectively. These values are consistent with findings from previous studies. The results of the Manning equation calculations revealed that the flow velocity does not differ significantly between these stations (8% higher at Siera). The base flow depth at the Gachsar and Siera stations is less than 1 m. Therefore, as indicated in the literature review, axial flow (propeller) turbines are not suitable for installation in these rivers because they need to be fully submerged and require at least 1 m of depth. Overall, the use of wide and short turbines, such as Savonius turbines, is suggested in the Karaj River. The energy analysis results show that the maximum monthly theoretical energy at Gachsar and Siera equals 38,500 and 125,500 kWh, respectively. However, considering a turbine with a 1 m2 swept area and a power coefficient of 0.2, the maximum monthly extracted energy is limited to 940 and 1,142 kWh at these two stations.ConclusionThis study presents a fast method for the theoretical assessment of hydrokinetic power, which was applied to two hydrometry stations in the Karaj dam watershed. The results of HG calculations revealed that the base velocity (V90) of 1.34 and 1.49 m/s is present at the Gachsar and Siera stations, respectively. According to the available depths at these stations, the use of wide and short turbines such as Savonius turbines is suggested. Each individual Savonius turbine with a unit swept area at Gachsar and Siera is estimated to extract a maximum monthly energy of 940 and 1,142 kWh, respectively.
Research Article
Post-harvest technologies
A. Khalaj; E. Ahmadi; S. Mirzaei; F. Ghaemizadeh; R. Abbaszadeh
Abstract
IntroductionGrape is a major horticultural crop with a high nutritional value in the world. The optimal geographic and climatic conditions in Iran have positioned it as one of the most important regions for grape cultivation in the world. Black rot, caused by Aspergillus niger, is a highly destructive ...
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IntroductionGrape is a major horticultural crop with a high nutritional value in the world. The optimal geographic and climatic conditions in Iran have positioned it as one of the most important regions for grape cultivation in the world. Black rot, caused by Aspergillus niger, is a highly destructive fungal disease that affects the grapes by targeting wounded areas. It causes crushing of the grapes, the falling of berries, and reduces transportation and storage properties (Ponsone et al., 2011). Various methods, such as fumigating bunches with sulfur dioxide and storing them in a modified atmosphere, have been used to control fungal rot and prolong the shelf life of grapes. However, each method has its limitations. Grape fumigation with sulfur gas is harmful to human health (Duarte-Sierra et al., 2016) and the efficiency of modified atmospheric storage on rot control and maintaining the quality of grapes depends on the type of variety, storage temperature, and especially gas concentration (Himelrick, 2003).Given the lack of efficiency in traditional methods, it is imperative to introduce modern techniques that can effectively disinfect microorganisms. These advanced methods offer several advantages, including the preservation of crop quality, an increase in crop shelf life, the promotion of good health, and substantial economic benefits. A technique of this type includes using non-thermal (cold) plasma (NTP) technology to eliminate food microorganisms (Bourke et al., 2018). The effect of cold plasma at atmospheric pressure on the reduction of bacterial populations in food products such as lettuce, tomato, strawberry, and cherry tomato has been reported (Bermúdez-Aguirre et al., 2013; Pasquali et al., 2016; Ziuzina et al., 2014). Research has shown that cold plasma can effectively inactivate Aspergillus in various orchard and agricultural products (Butscher et al., 2016; Ghorashi et al., 2020; Selcuk et al., 2008). The effect of cold plasma on the quality characteristics of the product during the post-harvest period has also been investigated. Blueberries treated with cold plasma for less than 15 minutes showed remarkable results: after 10 days, the fruit exhibited reduced lipid peroxidation and darkening, with no impact on the total anthocyanin content, pH, or firmness of the product (Hu et al., 2021). In a study by Rana et al. (2020), it was found that subjecting strawberries to 15 minutes of cold plasma with packaging after 5 days of storage at 25°C had no significant impact on pH, TSS, and moisture content of the fruit.The review of the literature reveals the absence of research on fungal disease control and grape quality evaluation following the use of NTP. This study aims to investigate the efficiency of plasma treatment in reducing the infection with Aspergillus fungi, along with examining the physical, chemical, and mechanical properties of Fakhri grape.Materials and MethodsThis research was conducted as a completely randomized design in a factorial experiment at four plasma levels (0, 10, 20, and 40 s) and five storage periods (1, 2, 3, 4, and 5 weeks) with three replications at 4°C. A plasma generator was first designed and manufactured in this study. A specifically designed and fabricated plasma application probe was also developed for grape berries. The individual grape berries were then sterilized with 1% sodium hypochlorite under a laminar hood for 2 minutes. Afterward, they were rinsed three times with sterile distilled water to remove any remaining disinfectant residue from their surfaces. Sterilized berries were immersed in Aspergillus spore suspension with 105 spores.ml-1 concentration. Finally, all samples were dried on paper filters and prepared for different plasma treatment durations (0, 10, 20, and 40 s). The treated samples were stored at 4°C, and the infection percentage and microbial load were measured on a weekly basis. To assess the preservation quality, chemical parameters such as pH, TSS, and TA, physical parameters (color change and weight loss), and mechanical properties were measured every week. Additionally, thermal imaging was performed weekly.Results and DiscussionPlasma application during storage significantly reduced the infection percentage and microbial load in Aspergillus-inoculated samples. At the end of the storage period, the infection percentage and microbial load in the 40-second plasma treatment were 5% and 2.5 CFU g-1 respectively, while in the control group, the infection percentage was 100% and the microbial load was 4 CFU g-1. At the end of the storage period, the lowest pH level in the plasma was observed for 40 s plasma. This could be attributed to effective contamination control, as fungal contamination leads to alkalization of the environment. The highest amount of TSS was also observed in control and 40 s plasma. But in the 10 and 20 s plasma treatment, the process of changes was gradual and not significant. The higher TSS level of control and 40 s plasma can be due to the weight loss caused by the spread of contamination and moisture leakage caused by damage to the tissue. This decrease in moisture leads to an apparent increase in the TSS index. Research has shown that plasma primarily affects the surface characteristics of products, and when applied with the appropriate voltage and duration, it does not alter the internal chemical properties (Hu et al., 2021). Over time, weight loss increased in all treatments. This increasing trend during the storage period is higher in control and 40 s plasma compared to 10 and 20 s plasma. Therefore, the weight loss in the control can be due to the spread of contamination and aging of the product over time. However, the weight loss in the 40-second plasma treatment can be due to the destruction of the fruit tissue caused by longer duration of the plasma application.In the current research, by increasing the duration of plasma application to 40 s, a significant decrease in L*, a*, and b* indices and an overall change in the color of the product was observed. Research shows that in blueberries, inappropriate duration of plasma treatment causes the loss of wax on the fruit surface and leads to darkening of the product (Hu et al., 2021). The highest and lowest changes in temperature drop were observed in the control treatment (5°C) and 10 and 20 s plasma (3 and 3.5°C, respectively). According to research, an increase in fungal contamination leads to a decrease in humidity, increases weight loss, and subsequently a decrease in product temperature. A decline in mechanical characteristics was noted for the control and plasma treated samples during the storage period. The lowest value for indicators was observed in the 40 s plasma treatment. However, no significant difference was observed in samples treated with plasma for less than 20 seconds compared to the control group up to the middle of the storage period. According to a report by Misra et al. (2014), plasma application can reduce tissue softness. Therefore, optimizing its plasma duration and intensity is very important (Pan et al., 2021). ConclusionOur experiments aimed to investigate the effect of NTP treatment on controlling Aspergillus infections while preserving the quality properties of Fakhri grapes. The obtained results are important for two main reasons. Firstly, an innovative probe was designed for plasma applications, specifically tailored to the shape and size of individual grapes in order to thoroughly cover them with plasma. Secondly, application of plasma was carried out for the first time and yielded valuable results, indicating that this technique can control fungal infections and preserve the chemical, physical, and mechanical properties of grapes.
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