Abjna-3-8-318-325.pdf

AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: 2151-7517, ISSN Online: 2151-7525, doi:10.5251/abjna.2012.3.8.318.325 © 2012, ScienceHuβ, http://www.scihub.org/ABJNA

Measurement of some engineering properties of sandbox seeds ( Hura crepitans ) * Idowu, D O; Abegunrin, T.P; Ola, F A; Adediran, A.A; Olaniran, J A Department of Agricultural Engineering, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria. ABSRACT The physical properties of kernels, grains and seeds are necessary for the design of equipment to handle, transport, process and store the crops. The physical properties of Hura crepitans seed have been evaluated as a function of moisture contents from 9.3 to 52.4% (wb). In the moisture range considered, seed length, width, thickness, one thousand weight and geometric mean diameter increased linearly from 20.4 to 22.8mm,21.1 to 23.0mm, 5.0 to 6.9mm ,860 to 1600g and 12.89 to 15.39mm respectively. The volume, sphericity, and surface area also increased from 3 2 758.38 to 1098.91mm , 0.63 to 0.69 and 522.55 to 744.09mm respectively, whiles the bulk 3 density and the true density are 0.55 and 13.40g/mm respectively. It was observed that material surface is the most determinant of the magnitude of the coefficient of static friction. The coefficient of friction was highest on plywood with 0.37 for seeds and 0.66 for kernel while the lowest coefficient of friction was recorded on stainless steel, 0.32 and 0.43 for seeds and kernels respectively. For all surfaces the kernels recorded the highest coefficient of friction. Also, the 0 0 kernel angle of repose was 26.2 which are higher than angle of repose recorded for seeds, 19.2 . The results of the experiment will contribute immensely to the existing knowledge aimed at solving the problems of equipments design to handle the processing of seeds. Keywords: Physical properties, moisture content, Density, Coefficient of friction, Angle of repose INTRODUCTION Sandbox tree (Hura crepitans ) is an evergreen tree that belongs to the spurge family (Euphorbiaceae ) that grows in the tropical regions of the world (Wikipedia encyclopedia, 2009). The tree can be recognized by the presence of many dark conical spines that covers the bark and its large heart shaped leaves with prominent secondary veins. The fruits produced are pumpkin shaped seed pods which are usually green when fresh and brown when dry. The fruit is characterized by its tendency to break with an explosive sound when ripe and dry, splitting the seedpods into segments catapulting the seeds as far as 100 m. In most parts of the world, the trees have been used as shade because of its large spreading branches. In some places, the leaves are used for medicinal purposes (Striweb.com, 2009) but the seed has not been fully exploited as there is dearth of information on the properties, traditional handling methods and utilization of the seeds. However, it has been reported that the seed contain oil and some essential vitamins. The oil may be useful in industries for even food, feed, paints, and cosmetics.

The knowledge of various physical, mechanical and chemical properties of agricultural products are very essential to the designs of suitable machines and equipment for the handling, processing and storage of these products. Size and shape of the materials are useful in sizing, sorting and other separation process. Bulk and true densities of the materials are important in order to design equipment for its processing, sorting, grading, transporting and storing. The angle of repose is important for designing package or storage structures and the coefficient of friction plays an essential role for transportation, handling and storage structures. In recent years, many researchers have investigated the physical properties of some seeds, these includes the sunflower seed (Gupta and Das, 1997); guna seed (Avaira et al., 1999); African breadfruit seed ( Omobuwajo et al., 1999); locust bean seed ( Ogunjimi et al., 2002); okra seed (Calisir et al., 2005); nutmeg seed (Burubai et al., 2006); sponge gourd seed (Ogunsina et al., 2009) and soya bean seed (Tavakoli et al., 2009). However, review of literatures shows that there is no information on the physical and mechanical properties of Hura crepitans. Therefore, the objective of this study was to

Agric. Biol. J. N. Am., 2012, 3(8): 318-325

investigate the moisture properties of the seed.

dependant

physical

method was chosen since there is no approved method for determining the moisture content of this type of oilseed material. The moisture contents (Wet basis) of the seed and kernel samples were determined by the relationship:

MATERIALS AND METHODS Bulk quantities of mature and dry sandbox tree (H. crepitans) fruits were collected from the premises of the University of Ibadan campus, Ibadan, Nigeria. The seedpods were broken manually to get the seeds (Plate 1A) and some of the seeds were shelled to obtain the kernels (Plate1B).

% Moisture =100 (W I – W f)/W i

(1)

Where: W i = initial weight of the seeds W f = final moisture content of the seeds Average moisture content of H. crepitans seed collected was found to be 9.3% (w.b.). The samples of the desired moisture content level were prepared by adding calculated amounts of distilled water and sealing in separate polyethylene bags. The samples o were kept at a temperature of 5 C in a refrigerator for a week to enable the moisture distribute uniformly throughout the samples. The test were carried out after removing the required quantity of the H. crepitans seed out of the refrigerator and was allowed to warm up to room temperature. This method has been used by Sessiz et al. (2007) and Tavakoli et al. (2009). Size: The size was determined by measuring the linear dimensions; length, width, and thickness of 100 randomly selected Hura crepitans seeds and kernel, using a vernier caliper. The geometric mean diameter (Dg), shpericity (Ø) and surface area (S) were determined from the following relationships

Plate 1 A: The Hura crepans seeds

Dg= (LWT)

1/3

(2)

Ø= S=

(3) Dg

(4)

Where L is the length; W is the width and T is the thickness. These relationships have being used by Moshenin, (1986); Ogunsina et al. (2009); and Tavakoli et al. (2009). Plate 1 B: Kernel of Hura creptans

One hundred seed mass: The thousand seed mass was determined using a digital electronic balance Tubol 005 model having an accuracy of 0.001 g. To evaluate the thousand seed mass, 1000 seeds were randomly selected from the bulk sample and weighed. The experiments were replicated three times.

The physical properties were measured at five different seed moisture content (9.3, 22.2, 32.0, 42.3, 52.4% w.b.) while that of the kernel was taken at 8.6% (w.b.). Moisture content determination: The initial moisture content of the samples was determined by o oven drying the samples at temperature of 105 C for 6 h adopted from Olaoye (2000) and Ozguven et al. (2005) for castor nut and pine nuts respectively. This

True volume, density and bulk density of the seed: According to Jain and Bal (1997) and Ozguven

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et al. (2005) the volume of the seed and kernel was given as follows: V=

replicates in each case. The angle of repose was calculated using the equation bellow which was adapted from literature [Kaleemullah and Gunasekar , (2002); Ozguven and Varsavusl (2005); Sessiz et al., (2007)]:

(5)

Where B = (WT)

0.5

= tan

(6)

The true volume of the seed was determined using the water displacement method (Moshenin, (1986); Ogunsina et al., (2009)). The seed was weighed in air and allowed to float in water. The volume of water displaced was recorded. This was repeated for the kernel and there were 5 replicates in each case. True density ( t) of the seed and kernel were calculated using the relationship: t=

Coefficient of friction: The static coefficients of friction of the seeds and kernels against five different surfaces namely: stainless steel, galvanized steel, mild steel, aluminum and plywood were determined as described by Ozguven et al. (2005) and Ogunsina et al. (2009). The inclined plane was gently raised and the angle of inclination at which the samples started sliding was read off the protractor. The tangent of the angle was reported as the coefficient of friction (Dutta et al., 1988):

Where w is the density of water; Ma and Mw are mass of seed or kernel in air and water respectively.

μ= tan

The bulk density was determined using the mass/volume relationship, by filling an empty plastic container of predetermined volume and weight with the seeds poured from a constant height, striking off the top level and weighing. This was also repeated for the kernels and the bulk density was calculated as: b=

RESULTS AND DISCUSSION Physical properties: The results of the experiments performed on the physical properties of Hura creptans and the effect of moisture content on them is as discussed below.

(8)

× 100

Where ε is the porosity, is the true density.

Linear dimensions: Average values of the three principal dimensions of Hura crepitans seeds i.e. length, width and thickness determined in this study at different moisture contents are presented in Table 1. It was observed that the moisture content affect the principal axis. From this, as the moisture content increased from 9.3% to 52.4% (w.b), the average length, width and thickness of the seeds varied from 20.4 to 22.8 mm, 21.1 to 23.0 mm and 5.0 to 6.9 mm respectively. The various results were plotted against the moisture content (Fig.1). The following regression equations were developed for the length, width and thickness of Hura crepitans seed with moisture content:

(9) b

is the bulk density, and

(11)

Where, μ is the coefficient of friction and is the tilt angle of the friction device. All the friction experiments were conducted in five replications for each surface.

Where b is the bulk density, M and V are bulk mass of seed or kernel (g), and the plastic container volume respectively. Owolarafe et al. (2007); Ogunsina et al. (2009); and Tavakoli et al. (2009) have used the same method for other crops before. The porosity of the seeds and kernels were calculated from the bulk and true densities using the relationship given by Moshenin (1986) as follows: ε= (1 -

(10)

Where H is the height of the cone and D is the diameter of the cone.

(7)

w

-1

t

Angle of repose: The angle of repose is the angle with the horizontal at which the material will stand when piled. This was determined by using a cylindrical container open at both ends. The cylinder was placed on a wooden table, filled with the seeds and raised slowly until it formed a cone of seeds. This was repeated for the kernels and there were five

L= 19.89 + 0.043Mc W= 20.03 + 0.067Mc T= 4.620 + 0.040Mc

320

2

(12)

2

(13)

(R =0.922) (R =0.855) 2

(R =0.955) (14)

Agric. Biol. J. N. Am., 2012, 3(8): 318-325

Çalişir et al. (2005) for Turkey okra seed, Sessiz et al. (2007) for caper fruit and Tavakoli et al. (2009) for soya bean seed. The regression equation for the effect of moisture content on Geometric mean diameter of Hura crepitans is as presented in equation 15.

Geometric mean diameter: The average values of geometric mean diameter of Hura crepitans seeds calculated at different moisture contents are given in Table 1. It is seen that the geometric mean diameter increased from 12.89 to 15.39 mm as the moisture content increased from 9.3 to 52.4% (w.b.) (Fig.2). Similar increasing trend have been reported by

2

2

Dg= 0.000Mc + 0.015Mc + 12.73 (R = 0.991) (15)

Table 1: Axial dimensions of Hura crepitans seed at different moisture contents Properties Moisture content (wb)

9.3

22.2

32.0

42.3

52.5

Length (mm)

20.42

20.80

21.30

21.40

22.40

Width (mm)

21.11

21.30

21.50

23.20

23.80

Thickness (mm)

5.02

5.60

5.90

6.10

6.90

Geometric Mean Dia. (mm)

12.89

13.50

13.89

14.43

15.39

Sphericity (decimal)

0.63

0.64

0.65

0.67

0.69

758.38

876.56

969.10

1098.91

1345.13

Surface area (mm )

522.55

572.56

606.11

654.16

744.09

M1000 (g)

860.00

980.00

1120.00

1320.00

1600.00

3

Volume (mm ) 2

Sphericity: The values of sphericity were calculated individually with Eq. (2) by using the data on geometric mean diameter and the length of the seed and the results obtained are presented in Table 1. The sphericity (Ø) of the Hura crepitans seed increased from 0.63 to 0.69 mm as the moisture content increased from 9.3 to 52.5% (w.b.). The trend is as shown in Figure 3. The lower sphericity is an indication that the seed cannot roll on its side but slide. This is very useful in the design of handling equipment for the seed. Similar trends of increase was reported by Sessiz et al. (2007) for caper fruit while Çalişir et al. (2005) and Tavakoli et al. (2009) reported a decrease in sphericity for Turkey okra seed and soya bean seed respectively. The regression equation is as shown below: -0.5Mc2

Ø=2e

-0.5Mc

+e

2

+0.628 (R = 0.99) (16)

Surface Area: The surface area of the Hura crepitans seed was calculated using Eq.3. The result is as presented in Table 1. The surface area of the 2 seed increased from 522.55 to 744.09 mm when the moisture content increased from 9.3 to 52.4% ( w.b). The result was as shown in Fig. 4. Similar trend has

Fig. 1: Effect of moisture content on the Principal dimensions of Hura crepitans seed

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been reported by Selvi et al. (2006) for linseed, Ișik and Ünal (2007) for red kidney bean grains, and Garnayak et al. (2008) for jatropha seed .Regression analysis was performed on the effect of moisture content on surface area of Hura Crepitans. The relationship is as shown below in equation 17. 2

2

Sa=0.069Mc +0.626Mc+514.8 (R =0.991)

(17)

Volume: The volume of Hura crepitans seed showed the marked variation with the moisture content in the range from 9.3% to 52.4% w.b. as shown in Table 1. The volume of seeds increased from 758.38 to 3 1345.13 mm . The correlation graph is shown in Fig 5. Similar increasing trend has been reported by Baryeh, (2002) for millet, Çalişir et al, (2005) for Turkey okra seed and Sessiz et al. (2007) for caper fruit. The regression equation on the effect of moisture content on the volume of Hura crepitans seeds is as shown below: 2

2

V = 0.211Mc + 0.023Mc + 749.8 (R = 0.991)

(18) Fig.3: Effect of moisture content on Sphericity of Hura crepitans seeds

Fig.2: Effect of moisture content on geometric mean Diameter of Hura crepitans seeds Fig. 4: Effect of Moisture content on Surface Area of Hura crepitans seeds

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trends of increase has been reported for Turkey okra seed (Çalişir et al., 2005), caper fruit (Sessiz, 2007), karanja kernel (Pradhan et al., 2008) and soya bean seed (Tavakoli et al., 2009). Effect of moisture content on the thousand seed mass was found to be related as shown below: 2

2

1000m=0.280Mc +0.335Mc+842.0(R =0.999) (19) Relationship between the seed and kernel Physical properties: From Table 2, the size distribution showed that about 56% of the seed by number and 50% by mass were of medium size, 18% by number and 29% by mass were large and 26% by number and 31% by mass were small seeds. Larger seeds were broader but not as thick and heavy as the medium and small ones. The following expression was developed to describe the relationship among the dimensions of the seed. L = 0.97 W= 4.07 T = 486.19 M

(20)

About 56% of the kernels were of medium size, while 14% were large and 30% small. This shows that most of the kernels are medium sized as the seeds. The kernel shows the following relationship and the dimensions.

Fig.5: The effect of Moisture content on the volume seed of Hura crepitans

l = 0.92 w = 3.39 t = 522.67 m

(21)

The general expressions that can also be used to describe the relationship between the dimensions of Hura crepitans seed and kernel: L= 1.30 l

(22)

W= 1.24 w

(23)

T= 1.09 t

(24)

M= 1.45 m

(25)

Where L is length of seed (mm), W is width of seed (mm), T is thickness of seed (mm), M is mass of seed while l is length of kernel (mm), w is width of kernel (mm), t is thickness of kernel (mm) and m is mass of kernel. In Table 3, the L/W ratio is lower than the L/T and L/M ratios; meaning that the width of the seed is higher than its length and this is also the same for the kernel. This is very useful in the design of a grading and cleaning machine for the seed.

Fig. 6: Effect of moisture content on one thousand seed mass of Hura crepitans seeds

Thousand seed mass: The thousand seed mass of Hura crepitans increased from 860 to 1600 g as the moisture content increased from 9.3 to 52.5% w.b. (Table 1). Figure 6 shows the relationship. Similar

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Table 2: Compare of Physical properties of Hura crepitans seeds and its kernels Property Unit No of replicates Seeds at 9.3% Mc (w.b.) Kernels at 9.3% Mc (wb) (w.b.) Length mm 100 20.42 15.68 Width mm 100 21.11 16.96 Thickness mm 100 5.02 4.62 Equivalent Dia mm 100 12.89 10.69 Sphericity mm 100 0.63 0.68 3 Volume mm 100 758.38 454.01 2 Surface area mm 100 522.55 358.88 Mass g 100 0.084 0.058 3 True density g/cm 5 13.40 6.00 3 Bulk density g/cm 5 0.55 0.56 Porosity % 95.9 90.60 Table 3: Dimension ratio of H. crepitans seed and values confirm that there is a low variation between kernel the principal dimensions of both the shelled and unshelled materials; hence, the seed cannot be Parameters Mean classified as spherical in shape so during the design L/W 0.97 of the handling equipments the seed will slide but not L/T 4.07 roll. L/M 486.19 l/w 0.92 The average seed mass of Hura crepitans seed and l/t 3.39 kernel were 0.080 g and 0.058 g respectively. These l/m 540.69 are higher than that of sponge gourd seeds. This L/l 1.30 indicates that Hura crepitans seeds are slightly W/w 1.24 heavier. The average true and bulk densities of the 3 3 T/t 1.09 seed are 13.4 g/cm and 0.55 g/cm while the 3 corresponding values for the kernel are 6.0 g/cm M/m 1.45 3 and 0.56 g/cm . Porosity values for Hura crepitans seed and kernel are 95.9 and 90.6%. The average values of geometric mean diameter, Mechanical properties: The result of experiment on sphericity, volume and surface area of the seed were 3 2 angle of repose and coefficient of friction carried out 12.89 mm, 0.63 mm, 758.38 mm and 522.55 mm on Hura crepitans were represented in Table 4. respectively and the corresponding values for the 3 kernels were 10.69 mm, 0.68 mm, 451.01 mm , 2 358.88 mm respectively (Table 2). These high Table 4: Mechanical properties of H. crepitans seed and kernel Property unit No of replicates Seed Kernel Coefficient of friction Galvanized steel decimal 5 0.39 0.52 Mild steel 5 0.36 0.54 Aluminum 5 0.39 0.52 Stainless steel 5 0.32 0.43 Plywood 5 0.37 0.66 Angle of repose 5 19.2 26.2 must be a little modification in the design of storage equipments for the two. Angle of repose: The angle of repose of the seeds o

o

Coefficient of friction: The coefficient of friction of Hura crepitans seeds and kernels were 0.39and0.52 on galvanized steel, 0.35 and 0.54 on mild steel, 0. 39 and 0.52 on aluminum, 0.32 and 0.43 on stainless steel and 0.37 and 0.66 on plywood, respectively. This result is within the results of

and kernels on wood was 19.2 and 26.26 respectively. This showed that the kernels are not as smooth as the seeds. A similar observation was reported for sponge gourd seed (Ogunsina et al., 2009). The wide range between the angle of repose of seed to that of kernel is an indication that there

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Kaleemullah, S., and Gunasekar, J.J. 2002. Moisturedependent physical properties of arecanut kernels. Biosystems Engineering Research, 25, 75-86.

Irtwange and Igbeka (2002) for African yam bean and Oje and Ugbor (1991) for oilseed bean. Conclusion: Having carried out investigations on the effect of moisture content on engineering properties of Hura creptance seed, it was discovered that all the linear dimensions, mass, volume, porosity and bulk density increased with increase in moisture content in the range of moisture content investigated. The findings from the research shows good agreement with some of the general trend and ranges obtained for other similar crops. It is of opinion that data from this test will be useful in the design and development of the appropriate machines for handling and processing of the seed.

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