JOURNAL OF AGRICULTURAL ENGINEERING RESEARCH
Year:2013 | Volume:14 | Issue:3|Papers Count:11

The losses of agricultural products decrease the market share and increase the need for imports, factors that can damage the national economy. Mechanical damage is a major factor in loss after harvest. This study examined the effect of vibration frequency and acceleration on damage to kiwi fruit during road transport. A factorial test (2 frequency×2 acceleration) in a completely randomized design with three replications was used. The rate of damage was the percentage of damaged fruit and the percentage of fruit bruised to a depth of greater than 2 mm (critical damage). Vibration frequencies of 7.5 and 13 Hz and accelerations of 0.3 and 0.7 g were selected for test. Analysis of the data indicated that the effect of frequency and acceleration was significant for the percentage of total damaged fruit (p<0.01). The effect of frequency was significant for the percentage of bruised fruit (p<0.05), but the effect of acceleration was not significant. Increasing the frequency and acceleration increased the mechanical damage to the kiwi fruit. The maximum average of total damaged fruits and fruits with a bruise depth greater than 2 mm were 40.3 and 30.71, respectively, at a frequency of 13 Hz and acceleration of 0.7 g.

The most important factors affecting onion rod digger performance are the shape of the rod and the ratio of peripheral speed to translational speed (kinematic index). This study investigated the effect of these parameters on n the performance of a rod onion harvester using a split-block randomized complete-block design with three replicates for three rod shapes (round, hexagonal, rectangular) and rod kinematic indices of 0.16, 1, 1.15, 1.30 and 1.44. In each experiment, the draft force and drawbar power for the rod and complete harvester, rotational torque and total required power for the rod, and the percentage of damage were determined. The results showed that rod shape had no significant effect on draft force, drawbar power (averaging 10571 N and 5285 W, respectively) and percentage of damage (averaging 1.98%); maximum torque and rotational power (averaging 64 N.m and 2394 W, respectively) were observed for the rectangular shaped rod. The maximum values for draft force and drawbar power (12018.7 N and 6009.3 W, respectively) were in the 0.16 kinematic index; the minimum values (9645.2 N and 4822.2 W, respectively) were in the 1.15 kinematic index. Maximum torque and rotational power (85 N and 3327.8 W, respectively) occurred for the rectangular shaped rod in the 0.16 and 1.44 kinematic indices, respectively. The results showed that, for minimum onion damage (priority) and power consumed, the best kinematic index was 1.15. The results of this research show that the rectangular rod shape in hard soil and the round rod shape in soft soil facilitated penetration; both occured in the 1.15 kinematic index. The total consumed power was from 3.5 to 3.8 KW per m of working width.

Rotary atomizers are commonly used in spray dryers to atomize feed. One destructive effect of wheel rotation is the creation of a vacuum inside the wheel that conducts hot air from the chamber into the wheel and can lead to atomizer blockage and an explosion. The present work determined the air-pumping characteristics of a rotary atomizer with a 50 mm wheel diameter. The vacuum pressure and power required to pump air was measured, as well as the friction power of the transporting parts, the shear power, and the air pumping power at rotational speeds of 7100-24100 rpm and gaps of 0.5-1.5 mm. Nearly 10% of atomizer power was consumed to pump air, 25% for air shearing, and 65% in the friction between the transporting parts. The results indicated that increasing rotational speed and the size of the gap increased the inlet air rate. This increase was more pronounced for the increase in gap size.

The shape of a submerged vane is a major factor in the design of a vane system and affects the performance and secondary currents generated by the vanes. This study investigated the effect of five vane shapes on bed sediment processes (local scour at the leading edge and transverse distribution of sediment downstream of the vanes) at four flow intensities for a total of 20 experiments. The results of the comparison of vaneinduced bed-level changes show that a vane with a rounded leading edge and decreased thickness in the longitudinal direction performed best at decreasing local scour at the edge of the vane by about 17.3% for U/Uc=0.78, 12.3% for U/Uc=0.93, 6.1% for U/Uc=1.10, and 45.8% for U/Uc=1.19. It was found that decreasing the cross-section area of the vane using shape modification decreased sedimentation and increased the sediment bed level on the high-pressure side of the vane.

The study of flow in compound channels with vegetated floodplains is essential to assessing the development of the stage-discharge relationship and sediment and pollutant transport. The present study experimentally investigated mean flow and turbulence characteristics in a prismatic compound channel. The experimental program consisted of vegetated and non-vegetated floodplains with different relative depths. The results show that vegetation had a significant effect on the flow characteristics of streamwise, lateral, and vertical velocity and Reynolds stress. For a given relative depth, the conveyance capacity of the channel decreased up to 31% for a vegetated floodplain over a non-vegetated floodplain. Although, the depth-averaged velocity varied significantly across the main channel, it was fairly constant over the vegetated floodplain. Strong secondary currents and lateral momentum transfer between the main channel and its floodplain led to high gradients in the depth-averaged velocity, bed shear stress, and turbulent kinetic energy at the interface.

The engineering properties of soils are generally affected by parameters such as mineral type, structure, and pore water salinity. The existing solutes of soil play a role in the electrochemical forces between particles and can change the index and mechanical properties of soil, including cohesion, compressibility, and compactibility. This study investigated the effect of sodium chloride, sodium sulfate, and sodium carbonate on compressibility and compactibility characteristics of clayey soil. For this purpose, 18 treatments were prepared using three types of salt at six concentrations (0%, 0.5%, 1%, 2%, 5%, 10% by weight of soil). Consolidation and compaction tests were conducted with three replications on the samples to determine the compression index (Cc), coefficient of consolidation (Cv), optimum moisture content (wopt) and maximum dry density (gdmax) of soil samples. Statistical analysis using SPSS software showed that the salinity of the soil had no significant effect on the optimum moisture content and maximum dry density of the soil. The compression index and coefficient of consolidation were significantly affected by both the type and concentration of the solutes in the saturated extract of the soil.

Pot cheese is a traditional cheese that is preferred for its characteristic aroma and flavor. This type of cheese is made without added starter cultures; the native lactic flora contribute to the ripening and development of the typical aroma and flavor of this cheese. It is essential to identify the type of lactic acid bacteria involved in the ripening process. In this study, pot cheese was made traditionally and then ripened in underground stroage for three months. Lactic acid bacteria were isolated and identified in the ripened cheese. Identification of isolates at the species level was performed using phenotypic and 16s rDNA methods. Overall, 51 strains were isolated; the dominant genera were Lactobacilli (37.3%) and Enterococci (25.5%). Other species belonged to Lactococci (19.6%), Leuconostoc (9.8%) and Pediococci (7.8%). At the end of the ripening period, Lactobacilli dominated and the changes were significant. Enterococci and Lactococci showed significant changes during ripening, but significant changes were not found for Pediococci and Leuconostoc. The dominant isolated species was Enterococcus faecium (8 isolates), Lactococcuslactis ssp. lactis (7 isolates), Lactobacilluscasei ssp. casei (4 isolates) and Pediococcusacidilactici (4 isolates). These species are recommended for use as starter cultures in the manufacture of pot cheese or a new type of cheese with similar flavor.

This study examined the influence of pre-frying treatments and oil type on the moisture outflow and oil uptake during the frying of potato strips. The pre-treatments were 6 min blanching in a 85oC a water bath containing 0.5% calcium chloride and immersion in a 1% solution of carboxymethyl cellulose; 6 min blanching in a 85oC water bath containing 0.5% calcium chloride and immersion in a 2% solution of salep; and the control condition. The type of oil used was CAO containing 0.1% bene kernel oil (BKO), 100 ppm unsaponifiable matter fraction of BKO and 100 ppm tert-butylhydroquinone (TBHQ). The potato strips were fried for 7 min. The results showed that the antioxidative additives and pre-frying treatments decreased moisture loss and oil absorption (R2>0.91). The ability of the UFB and BKO to decrease oil uptake was similar to that for TBHQ. The carboxymethyl cellulose decreased oil uptake better than did the salep.

This study investigated the survival of a probiotic strain of Lactobacillus acidophilus (LA-5) in jug cheese during storage (120 days at 6-8oC). The jug cheese treatments were: C (control), containing commercial starter FRC-65; LA, containing Lactobacillus acidophilus; and LAS, containing commercial starter and Lactobacillus acidophilus. The results showed that the amount of Lactobacillus acidophilus in the LA and LAS samples decreased 2 and 1 log cycles, respectively, during storage. The final amount of Lactobacillus acidophilus in LAS was greater than the minimum recommended for a therapeutic product (106-107 cfu/g). The use of commercial starter with the probiotic was more effective for maintenance of the probiotics than probiotics without commercial starter. The sensory evaluation showed that LAS had the highest significant flavor and texture ratings (p<0.05). It was concluded that probiotic Lactobacillus acidophilus can be used successfully in jug cheese without adversely affecting the cheese quality during ripening.