Saffron Stigma Separation by Oscillating Seperator and Wind Tunnel

Quality is an important factor in food products marketing, in the agricultural products, which the lack of agricultural equipment effects on it. Nowadays, separator devices play an important role in the quality of agricultural products. In this study, the separation of stigma from other components is analysed in oscillating separator, wind tunnel and combination of two states for determining their transposition. Oscillating separator experiments were performed based on completely randomized factorial design with 3 treatment of slope, amplitude, frequency and 3 replicates that each treatment is carried out at two levels. Considering that saffron components terminal velocities were different therefore wind tunnel experiments were done at different speeds within the range of saffron components terminal velocities. The results show that the combination of “wind tunnel-oscillating seperator” had the best seperation. In the oscillating seperator, the frequency of 35 Hz, amplitude of 7 μ and slope of 10 ̊ in comparison with other states had the optimum seperation. This combination was followed the average stigma separation of 86.29% and percent of impurities of 14.14%.


Introduction
Saffron is a spice derived from the flower of Crocus sativus, commonly known as the saffron crocus.Crocus is a genus in the Iridaceae family.Saffron flowers that take accont as the product of farm, include white carpel, three vivid crimson stigmas, three stamens, three same color sepal and petal that number of sepal and petal in usual flowers is six (Figure 1).Who stigma and a part of carpel from the other components is separated then the product is dried and sold as commercial saffron.

Figure 1. Saffron components
In the recent researches, petals were used in production of food color due to anthocyanin pigments (Hemmati et al., 2001), and saffron leaves can be considered for animal nutrition (valizadeh et al., 1899).According to the mentioned contents and applications of saffron in the pharmaceutical and coloring industry, it can be realized the importance of saffron separating.In the other hand, arranged flowers in one day should be opened on the same day, so, the flower pipe is splitted and the carpel is taken with three red stigmas within the flower pipe by the nail (Abrishami, 1897) which contributes to the pollution of saffron and reduction of its quality.
Agricultural products can be distinguished, usually based on shape, dimensions, physical properties and aerodynamic properties (Borgeie, 1974).Separation based on the aerodynamic properties is the oldest separation, by this method the seeds are put exposed to the air flow.To separate the stigma from flower, Emadi et al. (2008;2009) and Vale Ghozhdi et al. (2010) used physical and aerodynamic properties.The terminal velocity of flower components such as stigma, petals and stamen have been determined by the wind tunnel and results showed that it was possible to separate the stigma in harvesting moisture.In another study, Paschino and Gambella (2008) compared three models of cyclones with various structures such as the duct diameter, air velocity and the separation surface for the mechanical separation of saffron stigmas in the air flow.Results showed that cyclone type 3 which reduces the duct diameter by 14% and speed of the air included between 0.69 m/sec and 1.5 m/sec, the separation performed (96% of separate stigmasand without any damage in stigmas.In the separation based on friction coefficient, separation process is based on difference in the friction angle of mixture components.In this field, Emadi (2009) and Vale Gozhdi (2010) have taken a similar conclusion that there was a possibility of separating saffron components with this property.Hassan Beygy et al. (2010) studied the physical properties of saffron corm and determined the average values of the coefficient of friction for the three corm regions on steel, galvanized steel, plywood, rubber and polyethylene sheets: 0.517, 0.404, 0.462, 0.584 and 0.402, respectively.Electrostatic separating method is based on alternating absorption or desorption of charged particles in an electric field.Bani Hashemi et al. ( 2010) investigated the possible separation of impurities in the saffron, for example, chosing the nails.The results of the experiments showed the purification of the nail by 72%.
According to these studies, we observed that there were no researches about the stigma separation by oscillation separator, wind tunnel and combination in 2 states (oscillator-wind tunnel, wind tunnel-oscillator), and there were also no researches about influential parameters on oscillation seperator such as slope, frequency, amplitude on saffron separating.Therefore, it's important to separate the components of saffron, especially stigma.

Preparation of Samples
Saffron grows in limited regions of Iran, such as Khorasan, Fars, Yazd, Kerman, Markazi, Semnan, East Azarbaijan, and the production of it in the most provinces is new, except Khorasan and Fars.Samples were picked on farms located in the city of Marand in East Azarbaijan, then samples were cut from the upper receptacle by scissors, and the various components such as petals, leaves, stamens and stigmas were separated.The saffron components were dried in the oven at 103°C for 24 hours (ASAE S358.2 FEB03) to determine the moisture content.
That: Experiments were repeated 3 times to determine the initial moisture and took the average value as the initial moisture.

Seperation
In this experiment, 2 separator devices were used including oscillating seperator and wind tunnel with test section diameter of 17 cm with different speeds.Oscillation Separator is made up a "Sinocera Piezotronics Inc" oscillator, model JZK-2 and a screen (length: 32 cm and width: 22 cm) screwed on oscillator as shown in Figure 2. www.ccsen This seper experimen frequency about the determine a chute an Table 1.Before the test the amounts of each part of flowers was weighed by digital scale with an accuracy of 0.01 g.For testing, first oscillating separator was set on frequencies, amplitudes and slopes and then vibration is started and the sample was fed on a steep screen.Saffron components on the screen have been started to vibrate and each part took distance from other parts.Finally, after passing the length of oscillator screen, the amount of each part in the oscillator output was recorded.The optimal time for obtaining the maximum stigma separation percent in output was also noted.For determination of stigma separation percent, stigmas in the separator output were devided to its input value: According to Emadi (2009) and Vale Gozhdi ( 2010), the terminal velocities of saffron components have significant difference with each other which can be used for separation.For this purpose, first a 3 g controlled sample was applied to determine the range of separation speed at three replications.To measure the air speed, the hot wire speedometer of model "Yk-2004ah" with an accuracy of 0.1 m/s was used.Seperator evacuation materials have been fed into the wind tunnel test section by achute.Air speed was changed in the range of separation speed by the inverter and diaphragm until at the optimal speed, the highest percent stigmas separation was achieved.The output weighing of the wind tunnel was measured by scale and stigmas separation percent was determined according to Equation (2).

Wind Tunnel-Oscillating Separator
In this combination, the experiment was performed in two stages according to previous combination.Method of tests is on the basis of previous combination with a difference that first eight wind tunnel, separation tests were performed with 3 replications and the output materials were used for the input of the oscillating separator.

Initial Moisture Content
The results of initial moisture content of saffron components based on wet have been shown in Table 2.These values are the average of 3 replications.

Oscillating Separator
Average and variance analysis of stigma separation data were calculated by excel 2007 and MS-TAT.Results of variance analysis of three treatments (frequency, amplitude and angle of slope) on the stigma separation percent has been shown in Table 3. Effects of two factors including frequency and amplitude on the separation percent are significant in the probability level of 1%.Frequency × amplitude and frequency × slope angle interaction effects and even effect of frequency × amplitude × slope angle on the separation percent is significant in probability level of 1%.To achieve higher percent of stigma, separation average of oscillating separator, optimum time, etc. at various levels of treatments are shown in Table 4.According to the observations and results of the stigma and impurity average separation, the best separation with high quality is achieved in frequency of 35 Hz, slope of 10˚, amplitudes of 5 and 7 μ.In these characteristics, stigma separation is in high level while the impurity percent is low.In these two optimum cases, output impurities have the lowest leaves and petals than any other cases.The main reason of stigma reduction in output is related to saffron petals.Petals surround the stigmas and don't allow the stigmas to vibrate.This shows that the initial bulk of sample is one of the parameters that have an effect on separation.
The time and frequency is inversely proportional to each other and Table 4 depicts it.By increasing the frequency, the time for optimum separation are reduced.As in experiment No. 8, all inputs were observed in the seperator output with increasing a little time.It means that no separation has occurred to any of the components.According to this, we observed the time is effective on oscillating separation as the length of plate is effective.
In Figure 3, percent of pure and impure materials separation diagrams are given in constant frequencies and the effects of amplitude on stigma separation percent have been investigated.In diagram (3-a) the best separation point has occurred in slope of 10˚ and amplitude 5 microns with the average stigma separation percent of 88.10% (less than the others) but the low difference of stigma separation percent compared to others to its low percent of impure  According to the observations and results of the stigma and impurity average separation, the best separation with high quality is achieved at the frequency of 35 Hz, slope of 10˚, amplitudes of 5 and 7 μ.In these characteristics, stigma separation is in high level while the impurity percent is in low level.In these two optimum state, output impurities have the lowest leaves and petals of zero.In this mode of combination, there is less Impurity in the input an oscillating seperator because of reducing impurities in the first stage.So we can conclude that separation time is reduced with high quality separation, if obstacles againest the stigma vibrating reduced.
Results of variance Analysis of three treatments (frequency, amplitude and angle of slope) on percent of the stigma separation has been shown in Table 9.Effects of two factors frequency and slope on the percent of separation are significance in probability level of 1%.Interaction effects of frequency × slope angle on the percent of separation is significant in probability level of 1%.

Conclus
Based on t 1) In the w and second 2) The bes 35 Hz, am 3) The ini valve.Removing the petals can performe by creating obstacles such as a number of thin rods with same distance and parallel that place on the oscillating separator in several rows.6) The type of feeding is important in seperation, if we change the feeding type or large chute dimensions, that we can expect that Concentration and accumulation of components don't repeat again in wind tunnel.7) If obstacles against the stigma vibrating is reduced, the separation time decreases with high quality separation.8) Combinating the two seperators in one separator device which has the vibration frequency of 35 Hz, amplitude 7μ and slope of 10˚ and air blowing in the range of 1.9-3.7 m/s , will have good response like these states.9) Output of each seperators has stigmas with stamens, so using electrostatic separation can be effective in separating these two components.

4) If the o increasing
dried mass of sample, (g) Figu Figure Figure

Table 2 .
The initial moisture content of saffron components based on wet

Table 3 .
Variance analysis of treatments on stigma separation percent at second combination

Table 4 .
Stigma and impurities average seperation values and optimum separation time at first combination

Table 8 .
Stigma and impurities average seperation values and optimum separation time at second combination

Table 9 .
Variance analysis of treatments on stigma separation percent at second combination