جستجوی مقالات مرتبط با کلیدواژه « خواص مکانیکی » در نشریات گروه « مکانیزاسیون کشاورزی »

Preparation and supply of ready and semi-ready food products for consumers is important due to time constraints in today's world. For this purpose and in order to create such a platform, it is necessary and essential to know the characteristics of agricultural products. The knowing information about the properties and mechanical behavior of agricultural products is necessary in order to design mechanized and automatic agricultural equipment. The properties that are effective in cutting cellular materials are: compression, stretching, bending and cutting. These characteristics depend on the species, variety, ripening, moisture content and cell structure. In this research, mass density modulus, crushing resistance coefficient and efficient cutting coefficient of faba bean have been obtained, by using cutting theory and existing relationships. A completely randomized design with factorial testing was used to investigate the effect of cutting angle and cutting speed on these traits. The results showed that the effect of the cutting angle on the values of the mass density modulus and the crushing resistance coefficient is significant at the level of 1%, and with the increase of the cutting angle, the values of the crushing resistance coefficient decreased and efficient cutting coefficient increased. It was also found that the increase in cutting speed caused a decrease in crushing resistance and an increase in efficient cutting coefficient, while the changes in the mass density modulus did not follow a regular trend.

The firmness of the orange texture can be considered as an important criterion for determining the quality and freshness of this product and its texture characteristics have a great influence on its acceptability and marketability. Orange is an important product in the south of Kerman province, having sufficient knowledge and information about its texture mechanics is also important for the development of orange industries and processing equipment, especially orange concentrate production industries. In response to need the mechanical properties of the orange texture, punch test method was proposed as a suitable and non-destructive testing method. In this research, firmness, force, stress and consumption energy of five common orange varieties (Valencia, March, Washington Navel, Blood and Local Jiroft) was determined and compared by punch test method with seven punch diameters (4.3, 4.6, 9.7, 9.5, 11.1, 12.7 and 14.3 mm). The results showed that the effect of variables of punch diameter, variety, and also the interaction effect of punch diameter × variety on the force, firmness, stress and energy were significant at 1% level. The combination treatment of local cultivar with a punch diameter of 12.7 mm has the maximum value of force (79.0 N) and firmness (7.9 N/mm), and the minimum value of force (15.5 N) and firmness (1.5 N/mm) was obtained in the combination treatment of blood variety and punch diameter of 4.8 mm. The highest mean of stress (1.5 MPa) and the lowest mean stress (0.3 MPa) were in the combination treatment of local variety and punch diameter of 4.3 mm, and the combination treatment of blood variety and punch diameter was 14.3 mm.

Dimensions, shape and mechanical properties for the design of agricultural machinery for separation, harvesting and classification are important. The neural network as one of the main components of computational intelligence has important properties and wavelet transformation improves the accuracy of the model. In Research, by horizontal position of almonds, power failure, static brain, three varieties of almond named Mamaee, Rabie and Shahrood 12, in three levels of moisture (5.5%, 15% and 25% wb) and three speed loading (5,15 and 25 millimeters per minute) were determined. In the neural network, input parameters including three levels of humidity and three levels of speed as an independent variable were introduced into the model. The variables of fracture force, energy consumption and modulus of elasticity were considered as dependent variables of the model output. For more precision, various wave-lets such as Haar, db4, Sym2, Coif4 were first applied to these data. The R-criteria was used to evaluate the accuracy of the model. The cross validation results indicated the superiority of the Coif4 wavelet. In this algorithm, a feed forward network with a Levenberg-Marquardt algorithm with a sigmoid tangent function in the hidden layer and a linear function in the output layer were used. The results show the high accuracy of the neural network-wavelet. For the mamaee Variaty neural network with an arrangement of 1-5-2 with R = 0.9523, the arrangement 1-7-2 with R = 0.9745 and the arrangement of 1-4-2 with R = 0.8374 the best prediction for the modulus Elasticity has the power of failure and energy consumption. The R-criteria was used to evaluate the accuracy of the model. The cross validation results indicated the superiority of the Coif4 wavelet. In this algorithm, a feed forward network with a Levenberg-Marquardt algorithm with a sigmoid tangent function in the hidden layer and a linear function in the output layer were used. The results show the high accuracy of the neural network-wavelet.

In this study, edible films based on gelatin - russian olive flour (Elaeagnus angustifolia L.) incorporated with ZnO nanoparticles (2, 4 and 6% w/w) were investigated. The thickness, solubility, water vapor permeability, elongation to breakpoint of films with ZnO were higher than control ones. Color measurement of the edible films indicated that increasing the percent of ZnO nanoparticles, decreased the brightness(L*) and transparency and increased the a* and b* parameters of films (P < 0.05). In general, adding nanoparticles up to 4% increased the antioxidant capacity of the films compared to the control sample. Morphology images of the films showed that with the addition of ZnO the surface of the films was roughercompared to the control sample. Moreover, ZnO nanoparticles decreased the biodegradability of films. In general, films based on gelatin and russian olive flour with 2% ZnO are suitable films with good physical and chemical properties for food packaging.

In this research, peppermint and fennel essential oil (0.5, 1.5, and 1.5%) was used separately and in combination in pectin film to change the functional properties of films. The results showed that the addition of peppermint and fennel essential oil to the film caused a significant decrease in solubility and moisture content of the film (p<0.01). The effect of fennel essential oil on reducing the solubility was higher than peppermint. By increasing the concentrations of essential oil in the film, the opacity of films was increased from 0.72 Au.nm-1 to 5.97 Au.nm-1, but the use of the combination of essential oil in the film formed homogeneous emulsion and had less effect on opacity. The FTIR analysis showed a new interaction between essential oils and pectin. The most antioxidant activity was found in films containing 1.5% fennel essential oil, the phenolic compounds confirmed the antioxidant activity of the essential oil, the phenolic compounds content was (385/71 mg/g Gallic acid) for fennel and peppermint (322/83 mg/g Gallic acid). Water vapor permeability was decreased 50% by adding essential oil in films. In the results of mechanical properties, the elongation percentage of pectin films increased significantly by addition the essential oil (p<0.01), but the tensile strength and elastic modulus decreased. In terms of color changes, light absorption by phenolic compounds of essential oil decreased the yellowness index compared with the control sample, total color difference in the film containing essential oil, was higher than control films due to the presence of essential oil, the yellowness index and white index in the films containing essential oil decreased and increased, respectively.

The effect of enzymatic treatment time of microbial transglutaminase (MTGase) on the characteristics of whey protein isolate (WPI) films was investigated. Results shown that the properties of MTGase-treated films were affected by increasing the enzymatic treatment time. Enzymatic treatment at lower incubation time, i.e. for 1 h, significantly resulted in higher values of tensile strength (TS) and lower values of elongation at break (EB) as compared to control film. In the MTGase-treated films, the TS values decreased gradually and EB values increased progressively with increasing incubation time from 1 to 3 h. Water vapor permeability (WVP)and total soluble matter(TSM) of control film in comparison with MTGase-treated films decreased from3.6 ×10 10 to 2.31 ×10 10 g m-1 s-1 pa-1 and from 37.07 to 19.97 percent, respectively. However, as the time of enzymatic treatment was increased the TSM and WVP were gradually increased.

This study was carried out to determine some mechanical properties of barley seed including Deformation, Rapture Force, Rapture Energy and toughness as a function of moisture content (10.5%, 12.5%, 14.5% , 16.5%, db), loading rate (5, 15, 25, 35 mm.min-1) and grain size (small, medium, large). Tests were performed at 7 replications by the means of a factorial base plot experiment. The results showed significant effect of moisture content on all the properties (p>0.01).Also there is significant effect of grain size on rapture force, rapture energy and deformation and significant effect of loading rate on deformation at 1% level of probability. The interaction effect of moisture content- loading rate was significant on deformation and toughness (p>0.01) and on rapture force and rapture energy (p>0.05). The more percentage of moisture content, the more mean amount all the measure properties of barley seed. The mean amounts of rapture force and deformation increased linearly as the moisture content increased.

Storage conditions of product after harvest and during storage are important factors that affect the quality parameters of the products such as color and mechanical properties. The observance of effective issues on the fruit quality, such as weather conditions, harvest methods, timing of harvesting, temperature of storage and time of storage in maintaining of olive quality and reduce waste, will be very effective. Performance of mechanical testing and mechanical and colorimetric properties of products has an important role in study of qualitative and quantitative properties during storage. Moreover, the study of color and mechanical properties of products, such as olive is necessary, for use in machine design for processing and recovery processing lines in order to reduce waste.
In this study, two types of olives, bitter and sweetened with 1.5% NaOH were harvested and tested to study the effect of storage time on their color and mechanical properties. Olive fruits were stored in two temperatures (environmental conditions with 25 and refrigerator with 4) for 3 months. During this period, experiments were carried out at the intervals of 10 days. Universal testing machine and color meter devices were used for determining the mechanical properties and the color of olives, respectively. By performing a factorial experiment under completely randomized design, the effects of independent factors including storage time, storage temperature and type of olive on the measured properties (shear modulus, shear force, shear energy, modulus of elasticity, penetration force, yield strain, L*, a*, b*, h and c*) were studied.
The results of analysis of variance for shear modulus showed that the main effect of olive type, temperature, time of storage and the dual effects of these parameters were significant at the level of one percent. Analysis of variance for shear force showed that the effect of type, temperature, time of storage and interaction effects of type× temperature and type× time of storage were significant at the level of one percent. The results of data analysis for shear energy showed that the independent parameters, including the type, temperature, time of storage and the effects of dual and triple of their were significant at the level of one percent. According to the graphical results, shear modulus and shear energy of any type of olive on the thirtieth day with the fast steep increased. Water surface evaporation, changes in the texture of olive and a sharp drop in humidity are reasons for the sudden increase of shear modulus and shear energy on the thirtieth day. With increasing time of storage, shear strength and other mechanical properties for bitter and sweet olive increased. This result conformed to the results of Lavassani et al and Nanos et al. Analysis of variance of mechanical properties for olive fruit in penetration test showed that the effect of type and interaction effects of type and time of storage on modulus of elasticity were not significant. Analysis of variance of yield strain showed that the only effect of type was significant at the level of one percent. The results of mean comparison with Duncan test showed that during storage, penetration force and modulus of elasticity for bitter and sweet olive increased. This result correlated with the results of De Castro et al. The penetration force, yield strain and modulus of elasticity of sweet olives during storage were higher in comparison to bitter olives. The penetration force and modulus of elasticity of bitter and sweet samples stored at 4 were higher in comparison to the same sample in temperature of 25. This result correlated with the results of Nanos et al. Analysis of variance of colorimetric properties showed that the interaction effects of type and time of storage on L* were not significant. The effects of type and time of storage on a* and all effects on b* and c* were significant at 1% probability level. The results of mean comparison showed that the brightness and yellow of bitter and sweet samples increased with increasing time of storage compared to the first, tenth and twentieth days. The increase in L* and b* color characteristics correlated with the results of Piga et al. Color characteristics L*, b* and c* of bitter samples in each of the temperatures and days of storage were higher in comparison to sweet samples. In addition, the values of L*, b* and c* of bitter and sweet samples stored at 25 were higher in comparison to the same samples in temperature of 4.
The results of mechanical and colorimetric tests showed that by increasing the storage time, stiffness, shear strength and other mechanical parameters increased in both types of olives, and the L* and b* values of the samples were higher in comparison to the first, tenth and twentieth days. Bitter and sweet samples stored at 4 temperature displayed higher stiffness, modulus of elasticity, shear modulus, shear force and shear energy values and lower L*, b* and c* in comparison with the same samples stored at 25 temperature.

The present study examined the physical properties, rupture force, and milling characteristics of the common Hashemi, Alikazemi, and Tarom rice varieties in main and ratoon crops. The experiment was conducted as a factorial(3×2) randomized complete block design with five replications. The results revealed that the thickness (1.68 mm) and sphericity of grains (0.388) were less in the main crop thanin the ratoon rice (1.71 mm and 0.398, respectively). The Hashemi variety recorded the greatest length (7.58 mm). Alikazemi recorded the greatest width (2.03 mm), thickness (1.80 mm), geometric mean diameter (3.00 mm), sphericity (0.408), surface area (25.40 mm2), bulk density (561.54kgm-3), true density (1292.24 kgm-3), and thousand grain mass (26.96 g). The highest bending rupture force(24.68 N) and head rice yield (81.36%) was obtained for the ratoon rice crop of the Hashemi variety and the lowest corresponding values (19.6 N and73.41%, respectively) were recorded for the main rice crop of the Alikazemi variety (P<0.01). There was no significant difference in compressive grain rupture force between varieties or between the main and ratoon crops.

New edible composite films formed from salep (Orchis mascula) and 10%, 20%, and 30% (w/w) oleic acid were prepared by emulsification with the aim of improving the water vapor barrier and mechanical properties of the film. As oleic acid concentration increased up to 30% (w/w), oxygen permeability (27%), elongation at break (86%) and thickness (2%) of salep films increased significantly and the tensile strength (37%), solubility (39%), transparency (13%) and water vapor permeability (54%) decreased significantly (P<0.05). Increasing the oleic acid concentration produced a slight yellowish color in the salep film, but it was still transparent in appearance. It was found that oleic acid can be incorporated into the film and might be applicable for food packaging applications that require high water vapor permeability.

This study prepared new edible composite film by blending kefiran with whey protein. The film-forming solutions used different ratios of kefiran to whey protein (70/30, 50/50, 30/70, 10/90) and were cast at room temperature. The effects of the addition of whey protein on the physical, mechanical and water-vapor permeability (WVP) properties of the film were investigated. It was found that an increase in whey protein content from 0% to 50% (v/v) decreased WVP; however, further addition of whey protein increased WVP. This increase in whey protein content increased the tensile strength and extensibility of the composite film; however, these mechanical properties decreased at higher whey protein contents. Electron scanning micrography of the composite film showed it was homogeneous with no sign of phase separation between components. It was observed that these two film-forming components were compatible and that an interaction existed between them.

Evaluation of mechanical and electrical properties of agricultural products plays an important role in equipment design and optimizing post-harvest operations. Among the crops، tomato and its products are the major processing industries in the world and its economic importance is increasing. Considering the importance of the quality and various post harvesting uses of tomato، the evaluation of mechanical properties including rupture force and deformation and the work done to establish the rupture of two tomato cultivars (Petoearly CH and Newton) were studied under penetration test based on the electrical conductivity. These properties were measured at three levels of 1، 3 and 5 days after harvesting. The evaluated mechanical properties of both cultivars were decreased by increasing the storage time. Interaction of cultivar and time were significant at the 1% level، for all mechanical parameters except the deformation failure in both cultivars. The electrical conductivity of both cultivars was decreased by increasing the storage time. Interaction of cultivar and time on the electrical conductivity of both cultivars were significant at the 1% level. Significant relationships were found at the 1% level between electrical conductivity and mechanical properties except for deformation of Petoearly CH cultivar. Among the mechanical parameters، rupture forces and rupture works of both cultivars were highly correlated with the electrical conductivity.

Knowing physical and mechanical properties of the flowers is one of the important factors in designing، harvesting and post harvesting machines. A completely randomized design with factorial test was used in this research. Effect of shear speed، flower diameter، blade mode and shear angle on shear strength and shear energy per stem area unit and effect of picking speed and petal diameter on petal and sepal on the tensile strength and energy consumed per unit of area were determined for Rosa damascena Mill. Shear strength was decreased by increasing shear angle from zero to 25 and 45 degree but it was not significant. Energy per unit of stem area and elastic modulus were decreased by increasing shear angle and it was significant at 5% probability level. Increasing shear speed from 150 to 250 mm/min was not significant on decreasing shear strength and elastic modulus but was significant at 5% probability level for 350 mm/min. Energy per unit of stem area was decreased by increasing shear speed. Shear strength، elastic modulus and shear energy per stem area unit were decreased by increasing flower diameter. Two treatments (Picking speed and flower diameter) were not significant on the tensile strength and picking energy per unit for both picking petal and sepal.

Sugar، which can be extracted from sugar cane and sugar beet، is one of the most important ingredients of food. Conducting more research to increase the extraction efficiency of sugar is necessary due to high production of sugar beet and its numerous processing units in northern Khorasan province. In this research، the effect of temperature، time and the frequency of ultrasonic waves on mechanical properties of sugar beet and its extraction rate of sugar in moisture content of 75% were studied. In this regard، an ultrasonic bath in laboratory scale was used. The studied parameters and their levels were frequency in three levels (zero، 25 and 45 KHz)، temperature in three levels (25، 50 and 70 ° C) and the imposed time of ultrasonic waves in three levels (10، 20 and 30 min). Samples were prepared using planned experiments and the results were compared with control sugar beet samples. A Saccharimeter was used to measure the concenteration of sugar in samples. Two different types of probe including semi-spherical end and the other one with sharpened edges were used to measure mechanical properties. The studied parameters of frequency، temperature and time showed significant effect on sugar extraction and their resulted effect in optimized levels revealed up to 56% increase in sugar extraction compared with control samples. The obtained values of elastic modulus and shear modulus showed a decreasing trend. The obtained values of total energy of rupture، the total energy of shear، the maximum force of rupture، and the yield point of rupture showed an increasing trend. The frequency had no significant effect on the yield point of rupture and shear force.

Carboxymethyl cellulose (CMC)-polyvinyl alcohol (PVOH) blend film, containing 0-10% cellulose nanowhiskers (CNW), was produced through casting method, while physical properties of the films being investigated. CMC-PVOH-CNW nanocomposites, were prepared with a diluted suspension of cellulose nanowhiskers. Nanowhiskers suspension was prepared through acid hydrolysis of cotton linter by sulfuric acid and contained rod like particles, averaging lengths of 240 nm and diameters of 13 nm. A 6.86% reduction in total moisture absorbency was achieved by a 10% Wt PVOH addition to the CMC film. Ultimate break tensile strength and strain increased by 19.25% and 12.21%, respectively, through an addition of 10% Wt of PVOH. X-ray diffraction (XRD) test revealed uniform distribution of nanoparticles in biopolymer matrix. The addition of 10% Wt cellulose nanowhiskers decreased the moisture absorption of the blend film while increasing the ultimate tensile strength of the film by 17.65% vs. 47.05%, respectively.

Most consumers prefer natural coatings to the chemical ones to act as an enhancement of storage quality of fruits. In this research, quality of Thomson oranges coated with chitosan-clay nano composite edible coating plus fungicide-wax chemical coating was compared with a non-coated sample during storage for a period of 3 months through a factorial design (3×4). Orange samples were kept in a cold storage at 5oC temperature and 85-90% of relative humidity. The pH, titratable acidity of orange juice, weight loss percentage, peel shear and fracture forces as well as the coefficient of elasticity were assayed during storage. Results indicated significant differences among different coatings on all the measured dependent variables except on peel shear force (p<0.01). In addition, storage duration significantly affected weight loss, fruit peel cutting and fracture forces (p<0.01). Also fruits coated with Chitosan-clay showed reduction in weight loss, increase in pH, the highest fracture force as well as the coefficient of elasticity as compared with the control samples. Therefore, it is concluded that the coating increased fruit resistance to fungal diseases, retained inner texture strength and prevented the decrease in fruit quality.

The study of mechanical properties of Berberis not only is useful for design and optimization of transportation, processing and packaging equipment but also can prevent mechanical injuries and losses. In this study force, deformation, energy and toughness were measured at different moisture content levels including 70-76, 45-50, 25-30 and 7-10 percent (w.b.). The decrease of moisture content caused increasing rupture force from 1.387 to 2.679 N, decreasing shape deformation from 3.387 to 2.413mm, increasing toughness from 4.297 to 8.220 J/cm3 and decreasing rupture energy from 0.921 to 0.661mJ. Effects of loading speed, force orientation and their interaction were investigated on just fresh Berberis fruit. It was indicated that only force orientation was effective on all investigated properties except toughness. The moisture content was identified as an effective parameter on terminal velocity. It decreased from 9 to 4.5 m/s with decrease of moisture content from 76 to 7 percent (w.b.).

Iran is believed to occupy the second place, following turkey, among the apricot producing countries in the world. Iran is faced with problems in export of apricot due to little or non-observance of drying principals and inattention to world market requirements. The physical and mechanical properties of agricultural products are the most needed and important parameters for design and development of such systems as handling, grading, sizing, processing and packaging systems. Therefore, the physical and mechanical properties of apricot fruit, pit and kernel of the commercial cultivar Ghermeze-Shahrood was followed in this study. The results indicated the average values of length, width, thickness, geometric mean diameter, mass, volume and sphericity of the fruit as: 52.34 mm, 38.44 mm, 38.39 mm, 42.42 mm, 44.21 g, 45.87 cm3 and 81.07%, respectively. The average values of length, width, thickness, geometric mean diameter, mass, volume and sphericity were respectively 33.36 mm, 14.89 mm, 8.08 mm, 16.35 mm, 1.35 g, 1.37 cm3 and 49.01% for the pit. The values of coefficient of friction on steel, galvanized steel and plywood sheets were on the average determined as 0.417 for the fruit, 0.426 the pit and 0.523 for the kernel, respectively. The moduli of elasticity of the fruit vs. pit were 2.04 and 175.13 MPa, respectively. The minimum rupture force, deformation and toughness of the pit along with its thickness were determined at 0.2 to 0.4 (d.b) moisture contents. The obtained data can be employed for the design and development of postharvest, handling, grading, packaging and other processing equipments needed for export enhancement of the fruit.

Crops and agricultural products are subject to natural loading during growth. Different mechanical forces are also exerted on them during harvest. One product, sugar cane, experiences large shear forces are during harvest. An examination of the crop properties and machine parameters of sugar cane are necessary to develop appropriate cutting tools and the optimization and design of harvesting machines. The determination of such physical properties as diameter, moisture content, bulk density and mass per unit length is indispensable to this process. Mechanical properties related to cutting, such as maximum cutting force and strength, required energy and specific energy required for cutting are important. For this research, two experimental samples of sugar cane stalk (CP57, CP69) were collected from Amirkabir Research Farm in southern Khuzestan province. The samples were transported to the laboratory while maintaining the moisture content as constant as possible. The stalks were tested under quasi-static conditions using twotypes of blades (serrated and smooth) at three speeds (0.2, 0.5 and 1.35 m/min). The resulting data were analyzed using MSTATC and SPSS software. The effect of the variety on maximum cutting force was not significant, but cutting strength was observed to be significant at the 1% level. The effect of speed change on maximum cutting force was also significant at the 1% level. The effect of blade type on both maximum cutting force and cutting strength was significant at the 1% level. Increasing the speed from 0.2 to 0.5 and then to 1.35 m/min, especially using the smooth blade, increased the efficiency of cutting. However, increasing the speed from 0.5 to 1.35 m/min using the serrated blade increased cutting strength and energy. The serrated blade, at low speeds, was observed to require lower energy. Serration reduced energy consumption and lowered the required cutting strength because of adequate primary penetration of the blade into shell of the stalk, and the reduction of compression time.

An understanding of the strength of rice grains as affected by moisture content and temperature is important for analysis and prediction of cracking and/or breakage behavior during handling and processing. Further, the magnitude of these properties at various moisture contents and temperatures is needed for the accurate design of milling machinery so that grain damage is minimized. To determine the compressive mechanical properties of grains, two types of quasi-static compressive tests, whole kernel and uniaxialcompressive tests, of core specimens were performed at three moisture contents, 10.2%, 12.2% and 13.25% (w.b.), at grain temperatures of 35, 45, 55 and 64°C. Failure force, deformation and energy at the breaking point and apparent elasticity modulus were determined for whole grain tests, and compressive strength, failure strain, toughness modulus and compression modulus of elasticity were determined for uniaxialcompressive tests. Statistical analysis of the mechanical tests results indicated that moisture content and temperature have a strong influence on the properties examined. There was no significant effect on rice compressive failure properties. Moisture content had the greatest effect on the mechanical properties of rice. In general, all strength values except compressive strain increased as moisture content and/or temperature of grains decreased. For the different rice grain conditions studied, failure force varied from between 37.01 to 89.96N, while compressive strength varied from between 16.43 and 44.42MPa.