نشریه مهندسی بیوسیستم ایران
سال چهل و سوم شماره 2 (پاییز و زمستان 1391)

The main goal followed in the present study is to investigate the effect of developed plans on mechanization evolution and employment in the agricultural sector. Time series approach was applied. According to the results of the VEC model, substitution relationship between machine and labor accepted. In general, one unit of mechanization coefficient is substituted for one million employments in agriculture sector. Also, results showed that accomplishment of mechanization development programs had been affected by the improvement of its standing, but the existing gap between programs’ goals and their performance revealed inefficiency in acquiring Iran’s vision programs. Hence, exact implementation of development programs and an acquiring of the goals were considered as some of ways for reaching the optimum level of mechanization.

Variable Rate Application (VRA) based on Site Specific Crop Management (SSCM) is an effective approach for optimizing the application of agricultural inputs and preventing the undesirable environmental impacts. Design, construction and evaluation of a Map-Based VRA System was the main objective followed in this research. For variable rate application based on the generated map, a Direct Injection (DI) system was designed and constructed. This system was based on GPS data for positioning of sprayer, comparing GPS data with management map data, measurement of velocity and finally injection of the active ingredient into a carrier fluid using solenoid injectors proportionate to any management zone on the digital management map. The most important factor for evaluation of the developed DI system was system response (delay) time. Electrical conductivity was employed to assess the delay time. Independent variables including duty cycle, travel speed, carrier pressure, active ingredient pressure, active ingredient rate, as based on digital management map, and injection position were varied during the tests. Each test was implemented in three replications. Analysis of Variance and Duncans multiple range test were utilized to analyze the data. A factorial design of a completely randomized block was used for an evaluation of the interactions of various factors. The results revealed that response time depended significantly on carrier fluid pressure and injection position of the active ingredient.

A new method based upon Gabor filter and machine vision for the recognition of pistachio varieties is proposed throughout the current study. In the suggested method, the image of a set number of pistachios is considered to represent a texture; instead of one by one pistachio processing (which is actually done in the current methods) the new method is expected to represent a higher rating as well as a higher performance. To evaluate the proposed method, it was applied on an image of a set of pistachio's containing 1000 sub-images of 5 varieties of the fruit and using a K-means clustering to classify the product. The experimental results confirm the efficiency of the method by a classification rating of 94.8%.

A non-destructive, rapid and low-cost determination of date fruit moisture content is one of the most determining factors in maturity assessment and processing of this valuable product. On the other hand, the potential of Near Infrared (NIR) spectroscopy in nondestructive internal quality evaluation of agricultural products has been proved throughout several studies. In this research, three modes of near infrared spectroscopic measurements namely, reflectance, transmission and interactance, were compared for their ability to non-destructively estimate moisture content of ‘Mazafati’ date fruits. Spectral acquisitions were carried out through a photo-diode array (PDA) spectrometer in the range of 900-1700 nm. The spectra were then smoothed through Savitzky-Golay algorithm and preprocessed by Multiplicative Scatter Correction (MSC) method. Finally, the Partial Least Squares (PLS) regression method was applied to develop moisture content predicting models in each mode. The results indicated that the interactance mode provided the most accurate estimates of moisture content with a coefficient of determination (Rcv2) of 0.922, Root Mean Squares Error of Cross Validation (RMSECV) of 1.57% and Residual Predictive Deviation (RPD) of 3.60. The reason for this priority could be due to the lower level of such irrelevant information as distance variation of sample and probe and as well due to the lower effect of surface irregularities in the interactance mode.

Dryland winter wheat (Triticum sativum L.) generally grown in rotation with fallow or chickpea (Cicer arietinum L.) constitutes a major crop in the west region of Iran. Information is limited on the success of more intensive dryland cropping systems while applying conservation tillage management. An experiment was conducted to determine the effect of five tillage systems on soil physical properties and on crop yield in a winter wheat-chickpea rotation during a 4-year period on a silty clay loam in Tajarak Research Station (Kaboudarahang Township), Hamedan. Tillage treatments were comprised of Conventional Tillage (CT: mouldboard plow + disk), Reduced Tillage (RT: chisel plow + roller packer), Minimum Till (MT: sweep plow + roller packer), CYT: Cyclotiller + roller packer and No-Till (NT: direct planting). A randomized complete block design of four replications was employed. Some soil physical properties including: bulk density and permeability were assessed. Also wheat yield and yield components were determined. Tillage treatments exerted significant effects on bulk density and permeability. RT exhibited lower bulk density and higher permeability among treatments. Mean grain yields over the three seasons were recorded as 1050 Kg ha−1 for RT, 1030 Kg ha−1 for CYT, 982 Kg ha−1 for MT, 974Kg ha−1 for NT and 932 Kg ha−1 for CT. Average grain yields while applying conservation tillage were greater than those using CT treatment. This study revealed that a wide range of conservation tillage systems are adaptable for an intensive dryland cropping systems for the semiarid areas of Hamedan. Therefore the traditional system of applying moldboard plow, following chickpea cultivation could be replaced by conservation tillage systems that can increase yield and will likely improve soil properties in the long run.

One of the basic adjustments in application of agricultural implements, particularly tillage tools, is their work in a leveled state while in operation. Throughout the ongoing research, and by application of electronic and hydraulic circuits, an intelligent system was designed, developed and evaluated. The device is expected to perform the plow longitudinal as well as lateral adjustments at the beginning and during the plowing operations. A mounted moldboard plow was made use of, while simultaneously making measurements and recordings of the depth of plowing. A split plot experiment in the framework of a complete randomized block design of three replications (3×2×3) namely: the leveling of the plow in 3 levels (longitudinal, lateral, vs. the common practice (conventional); basic plowing depth at 2 (15 and 20 cm) levels and 3 levels of forward speed (3, 5, 8 km/hr) was employed. Variance analysis of the measured plowing depths indicated significant differences (P<0.05) as regards the interaction effects among the three factors of plow leveling, plowing depth, and forward speed. The plowing depths, measured at different treatment levels of the above three variables (LSD of 0.05) indicates the necessity of a close control of the longitudinal as well as lateral adjustments of the plow. Quick response of the system, particularly at higher speeds is indispensable. In other words, the speed of reflection of the system must be closely related to the forward speed.

Doogh- the popular Iranian drink- is a product of lactic fermentation of milk and its dry matter standardized by dilution of yoghurt (following fermentation) or milk (prior to fermentation). One of the basic problems occurring during its storage is serum separation. Optimum consistency accompanied by no separation of serum during storage are two desirable characteristics looked for. High Methoxyl Pectin (HMP) is proposed to prevent serum separation and modify rheological properties of the fermented dairy drink. Since electrostatic forces play in important role on stabilization of Doogh through with HMP, salt concentration and ionic strength of the medium affect the HMP stabilizing behavior. On the other hand, homogenization affects stability of Doogh by changing its particle size distribution. In this study, 0.25% HMP was added to saline water (0.5 and 1%) with the resulting solution added to yoghurt until the Doogh of 4%dairy solid non fat was produced. The final product was homogenized at either 150 or 250 bar and then their particle size distribution and rheological properties evaluated. The results revealed that salt significantly affected the stabilizing behavior of HMP and particle size distribution characteristic of HMP stabilized the product Doogh.

Enzymatic acidolysis of canola oil through caprylic and capric acids was investigated for making structured lipids. Lipozyme TL IM, an sn-1,3 specific Thermomyce slanuginosa lipase, was utilized as the biocatalyst in the batch reactor. Reaction conditions were designed according to Taguchi’s method considering fatty acid to oil ratio, at three levels (1:1, 2:1, 3:1), enzyme load (4, 8 and, 12%), temperature (45,55 and 65°C) and reaction time (15, 30 and 45 h). Fatty acid profiles of reaction products were analyzed through gas chromatography (GC) and iodine value (IV) variations determined from fatty acid composition. The reaction products, under optimum conditions, were compared in terms of the fatty acid distribution and molecular species of triacylglycerols. The results showed that fatty acid composition of canola oil was modified by the reaction. Acidolysis reaction in the presence of Lipozyme TL IM at 55°C, at the fatty acid to oil ratio of 3:1 and 12% enzyme level resulted in the highest molar percent of caprylic (37.2%) and capric (38.9%) acids in canola oil following 15 h of incubation. But, the difference between caprylic and capric acids in the acidolysis reaction for each enzyme was not significant. As a result of reaction with caprylic and capric acids, iodine value of canola oil revealed a significant decrease (from 118.5 to 78.8). Also, the results of the study indicated that by use of Lipozyme TL IM, 49.5 and 53.4 molar percents of caprylic and capric acids, respectively, were placed at sn-1,3 positions.

Ripening is considered as the most important biochemical event in the cheese technology. Presence of whey proteins in UF-cheese leads to such abnormal behaviors and characteristics as slow ripening, weak flavor, and soft and undesirable texture. Since temperature and time are the most important environmental factors in cheese ripening, the aim of the present study was chosen to investigate the effects of these factors on the improvement of Iranian UF- cheese ripening and on the use of a modeling technique for prediction of quantitative and qualitative changes as a function of these factors in ripening. Samples were incubated at 5, 10, 15 and 20˚C temperatures for 1, 3, 6 and 9 weeks and analyzed at the end of each period. (pH4/6-SN/TN, NPN/TN, NPN/SN) and (ADV) were made use of as indexes for proteolysis and lipolysis, respectively. Data were analyzed through SAS and modeled by MatLab and as well by Excel. Zero order, first order as well as Weibull kinetic Eq. and also arrhenius Eq. were made use of to model the data while correspondence of each model with laboratory data being reported. Increase in the temperature led to increase in proteolysis and lipolysis indexes. Q10 of pH4/6-SN /TN, NPN/TN, and ADV were recorded as 1.403011, 4.724578 and 1.426353, respectively.

A cause for breakage of rice kernels during the whitening process could be assumed to be due to the produced heat. It is partly because of abrasion and friction of grains produced by contact against themselves and/or against cone and concave. In this study the effect of different temperatures of brown rice on rice kernel's breakage during the whitening process was investigated. Khazar cultivar was utilized throughout the experiment. Rough rice samples were dried up to 10-11 percent moisture content. Samples were hulled to the point of 90±2% through a rubber roll husker. The samples were packed in plastic bags and stored in –13, 5, 18, 25, 35, 45 and 55 ºC. Whitening was performed through a pilot friction type whitener lasting for three different time intervals of 30, 35, and 40 seconds. A factorial experiment consisting of two factors of brown rice temperatures and different whitening times as based on a completely randomized design of six replications was taken into account. The results revealed that rice temperatures up to 25 ºC did not significantly affect milled rice yield. However yeild decreased in temperatures exceeding 25 ºC. The reduction was 1.94% when temperature was raised to 55 ºC. Broken grain percentage increased for about 3.7% when temperature increased to the 55°C. The lowest brightness index was observed when temperature was set at 5-25 ºC. At – 13 ºC and at 35-55 ºC the brightness index was recorded higher than those at the other temperatures.