**5. Methodology for evaluating soybean properties**

**Sample preparation:** Dry mature Soybeans [Glycine max.] are normally used for all the experiments. Before the experiments, the grains were further cleaned by removing those that were physically bad, unhealthy or broken. The moisture content of the grain would be determined using a standard method. Physical properties were determined at the initial moisture content. Thereafter, grain sample of the desired moisture levels were prepared by adding calculated amount of distilled water and sealed in separated polythene bags. The samples would be kept at about 278 0K in a refrigerator for 1 week to enable the moisture to distribute uniformly throughout the sample. Before the commencement of a test, the

• To obtain graded lots of seed which will meet home and international testing standards for the variety under consideration, in terms of purity, viability, vigour and size

• To remove completely any seeds, the sale of which in a batch may contravene the

• To remove all contaminants that is capable of damaging subsequent processing machinery such as size reduction machines. Typical contaminants include weed seeds,

It is important to identify differences in the physical properties of the seeds and the contaminants that will enable the machine (to be designed) make them flow in different

Typically, most processing machines identify differences in properties between good seeds and contaminants. For example a sieve identifies size while other machines identify a combination of properties such as specific gravity table. The shaking table for example identifies friction, size and density of the seeds. The air-screen cleaner for example make use of differences in size, shape and density of the seeds and such machine range from a small, one fan, single screen machine to the large multi-fan eight screen machine with several air columns. Other machines that are used for primary processing include threshing machine, from simple hand operated threshers to high capacity multi cop threshers, combine harvesters, winnowers, air-screen separators (oscillating or vibrating), graders (band, spiral), separators (spiral, table, magnetic, electrostatic, colour, pneumatic, and so on). **Secondary crop processing**: It involves processing of food for direct consumption. This requires grinding, milling, oil extraction and so on. To accomplish these, machines are used such as size reduction machines such as milling machines, dehullers, grinding machines, oil

**Sample preparation:** Dry mature Soybeans [Glycine max.] are normally used for all the experiments. Before the experiments, the grains were further cleaned by removing those that were physically bad, unhealthy or broken. The moisture content of the grain would be determined using a standard method. Physical properties were determined at the initial moisture content. Thereafter, grain sample of the desired moisture levels were prepared by adding calculated amount of distilled water and sealed in separated polythene bags. The samples would be kept at about 278 0K in a refrigerator for 1 week to enable the moisture to distribute uniformly throughout the sample. Before the commencement of a test, the

• Seed dimensions: length, width, thickness, geometric mean diameter

**Requirements for seed cleaning:** 

Noxious Weeds Act, of some countries.

straws, leaves, stones and soil particles.

directions. Such properties include the following:

• To avoid any loss of good seeds in the cleaning process. • To avoid excessive wear that may be due to sorting machines.

**5. Methodology for evaluating soybean properties** 

variation

**Principles of separation:** 

• Specific gravity • Falling rate (float) • Surface texture, friction

• Resilience (ability to bounce) • Electrical conductance

• Colour

press and so on.

required quantity of the grain was taken out of the refrigerator (if kept there to cool), and allowed to warm up to room temperature at about 305 0K.

**Physical properties**: The physical properties of Soybean to be determined include linear dimensions, mass, bulk density, seed density, volume, surface area, sphericity, porosity, coefficient of static friction on structural surfaces and angle of repose, angle of internal friction, terminal velocity. Experiments were conducted at five levels of moisture content in the desired range and replicated five times. Average values were normally reported. The choice of the range of moisture content was due to the fact that the lower limit was the safe storage moisture content, and the upper range, the maximum moisture content obtainable after the seeds were soaked overnight.

**Linear dimensions and geometric mean diameter**: To determine the size of the grain, 10 sub samples each consisting of 100 grains were randomly taken. From each sub sample, 10 grains were taken and their three linear dimensions namely, length (L), width (W) and thickness (T) were measured with a venier calipers having accuracy of 0.01mm. The geometric mean diameter (DGM) of the grain was calculated by using the following relationship (Sreenarayanan et al 1985, Sharma et al 1985).

$$D\_{GM} = \left(LWT\right)^{1/3} \tag{1}$$

**Test weight:** Sub samples of One, one hundred and one thousand soybean grains from each sample were randomly selected and weighed. The averages of the replicated values are usually reported.

**Bulk and seed density:** A method similar to that reported by Shephered and Bhardwaj (1986) can be used to determine the bulk density at each moisture level: a 180 ml cylinder was filled continuously from a height of about 15 cm. Tapping during filling was done to obtain uniform packing and to minimize the wall effect, if any. The filled sample was weighed and the bulk density of the material filling the cylinder was computed (Shephered and Bhardwaj, 1986; Deshpande and Ali, 1988; Mohsenin, 1970). The seed density of the grain can be determined by the liquid displacement method to determine the seed volume similar to that reported (Shephered and Bhardwaj, 1986; Deshpande and Ali, 1988).

**Sphericity and porosity**: According to Mohsenin (1970), sphericity ф, was calculated using the formula.

$$
\phi = \frac{\left(L\mathcal{V}T\right)^{1/3}}{L} \tag{2}
$$

Fractional porosity is defined as the fraction of space in the bulk grain which is not occupied by grain. Thompson and Isaacs (1967) gave the following relationship for fractional porosity.

$$\mathcal{E} = \frac{(1 - \rho\_b)}{\rho\_s} \text{x100} \tag{3}$$

where,

*ε* = fractional porosity *ρb* = bulk density of the seed

*ρS* = Seed density

**Angle of repose**: The emptying angle of repose θ is normally determined at the moisture levels using the pipe method (Henderson 1982, Jha 1999). A pipe of 40 cm height and 106 mm internal diameter was kept on the floor vertically and filled with the sample, Tapping during filling was done to obtain uniform packing. The tube was slowly raised above the floor so that the whole material could slide and form a heap. The height above the floor H and the diameter of the heap D at its base were measured with a measuring scale and the angle of reposes θ of the soybean computer using the equation;

$$\theta = \operatorname{Arc} \tan(2H/D) \tag{4}$$

**Surface area:** The surface area of the grain can be found by analogy with a sphere of geometric mean diameter for the different levels given by (McCabe et al., 1986)

$$S = \pi D\_{GM}^2\tag{5}$$

**Coefficient of static friction**: The coefficient of static friction for seed grain can be determined against structural surfaces such as plywood (with grain parallel to direction of motion and then with grain perpendicular to direction of motion), galvanized steel (GS), glass, concrete and so on. A bottom less wooden box of 150 mm x 150 mm x 40 mm was constructed for this purpose. This was similar to that reported by (Oje, 1994). The box shall be filled with soybean grains on an adjustable tilting surface. The surface would be raised gradually using a screw device until the box started to slide down and the angle of inclination read on a graduated scale.

**Terminal velocity**: The terminal velocity of soybean at different moisture content can be determined using an air column (Polat et al., 2006). For each test, a seed was dropped from the top of a 75 mm diameter, 1 m long glass tube. The air was made to flow upwards in the tube from bottom to the top and the air velocity at which the sample seed was suspended was noted with an anemometer having at least 0.1 m/s sensitivity.

**Angle of internal friction**: To determine the angle of internal friction of soybean at different moisture contents, the direct shear method can be used according to Uzuner (1996), Zou and Brucewitz (2001), Molenda et al.( 2002) and Mani et al.( 2004). Typical velocity to be used during the experiment is 0.7 mm/min (Kibar and Ozturk, 2008) and the angle of internal friction can be calculated using the following equations:

$$
\sigma = \frac{N}{A} 100 \tag{6}
$$

Where: σ - normal stress (kPa), N - load applied over sample (kg), A - cellular area (cm2),

$$
\sigma = \frac{T\_s}{A} 100 \tag{7}
$$

Where: τ – stress of cutting (kPa), Ts – strength of cutting (kg),

$$
\pi = (\mathbb{C} + \sigma t g \phi) \tag{8}
$$

Where: C- cohesion

#### **6. Rupture force and rupture energy**

To determine the rupture force and rupture energy, a Universal Testing Machine (UTM) can be used such as Instron Universal Testing Machine reported by Tavakoli et al. (2009). It was equipped with a 500 kg compression load cell and integrator. The measurement accuracy was

during filling was done to obtain uniform packing. The tube was slowly raised above the floor so that the whole material could slide and form a heap. The height above the floor H and the diameter of the heap D at its base were measured with a measuring scale and the

**Surface area:** The surface area of the grain can be found by analogy with a sphere of

<sup>2</sup> *S D* = π

**Coefficient of static friction**: The coefficient of static friction for seed grain can be determined against structural surfaces such as plywood (with grain parallel to direction of motion and then with grain perpendicular to direction of motion), galvanized steel (GS), glass, concrete and so on. A bottom less wooden box of 150 mm x 150 mm x 40 mm was constructed for this purpose. This was similar to that reported by (Oje, 1994). The box shall be filled with soybean grains on an adjustable tilting surface. The surface would be raised gradually using a screw device until the box started to slide down and the angle of

**Terminal velocity**: The terminal velocity of soybean at different moisture content can be determined using an air column (Polat et al., 2006). For each test, a seed was dropped from the top of a 75 mm diameter, 1 m long glass tube. The air was made to flow upwards in the tube from bottom to the top and the air velocity at which the sample seed was suspended

**Angle of internal friction**: To determine the angle of internal friction of soybean at different moisture contents, the direct shear method can be used according to Uzuner (1996), Zou and Brucewitz (2001), Molenda et al.( 2002) and Mani et al.( 2004). Typical velocity to be used during the experiment is 0.7 mm/min (Kibar and Ozturk, 2008) and the angle of internal

> <sup>100</sup> *<sup>N</sup> A* σ

<sup>100</sup> *Ts A* τ

 σ = + ( ) *C tg*φ

To determine the rupture force and rupture energy, a Universal Testing Machine (UTM) can be used such as Instron Universal Testing Machine reported by Tavakoli et al. (2009). It was equipped with a 500 kg compression load cell and integrator. The measurement accuracy was

Where: σ - normal stress (kPa), N - load applied over sample (kg), A - cellular area (cm2),

τ

= *Arc H D* tan(2 / ) (4)

*GM* (5)

= (6)

= (7)

(8)

angle of reposes θ of the soybean computer using the equation;

was noted with an anemometer having at least 0.1 m/s sensitivity.

friction can be calculated using the following equations:

Where: τ – stress of cutting (kPa), Ts – strength of cutting (kg),

**6. Rupture force and rupture energy** 

inclination read on a graduated scale.

Where: C- cohesion

θ

geometric mean diameter for the different levels given by (McCabe et al., 1986)

0.001 N in force and 0.001 mm in deformation. The individual grain was loaded between two parallel plates of the machine and compressed along with thickness until rupture occurred as is denoted by a rupture point in the force-deformation curve. The rupture point is a point on the force-deformation curve at which the loaded specimen shows a visible or invisible failure in the form of breaks or cracks. According to them the point was detected by a continuous decrease of the load in the force-deformation diagram. The loading rate of 5 mm/min was used according to ASAE (2006a). The energy absorbed by the sample at rupture was determined by calculating the area under the force-deformation curve from the relationship:

$$E\_a = \frac{F\_r D\_r}{2} \tag{9}$$

Where Ea is the rupture energy in mJ, Fr is the rupture force in N and Dr is the deformation at rupture point (Braga et al., 1999).


MC= moisture content, NAV= not available

Table 4. Effect of moisture content on mass and dimensional properties of some soybean cultivars


MC= moisture content, NAV= not available

Vt = terminal velocity

Table 5. Effect of moisture content on density, sphericity, porosity and terminal velocity of some soybean cultivars


MC = moisture content, NAV= not available, PWLG = plywood parallel to grain, PWDG = plywood perpendicular to grain \*PLWD = plywood

Table 6. Effect of moisture content on angle of repose and coefficient of static friction of some soybean cultivars

### **7. Estimated values of soybean properties**

Some typical values and models of physical, mechanical and aerodynamic properties of soybean cultivars are reported in this section (Tables 4 to 6). Table 4 shows the effect of moisture content on mass and dimensional properties of some soybean cultivars**.** Table 5 shows the effect of moisture content on density, sphericity, porosity and terminal velocity of some soybean cultivars**.** Table 6 shows the effect of moisture content on angle of repose and coefficient of static friction of some soybean cultivars.

#### **8. General comments**

60 Soybean Physiology and Biochemistry

JS- 7244 8.7- 25.0 1216 - 1124 735 - 708 80.6 – 81.6 40 - 37 NAV Deshpande et

TGX 1440-1E 10.5- 34.1 1184 - 1076 720 - 631 79 – 73.3 23.6 – 34.2 NAV Manuwa, 2000

Sphericity (%)

616.7 85.87- 78.23 25.64 –

608.4 86 – 74.9 23.46 –

689.3 75 to 72 51 to 44.2 7.13 to

39.6 1465 - 1074 714 - 638 79.1 – 72.7 19.5 – 33.7 NAV Manuwa, 2007

Coefficient of static friction

0.600

0.601

0.4877 – 0.6249

0.35\*

0.361

steel PWLG PWDG Glass

719.00 91- 87 22.58 –

87.25 to 84.75

Porosity

43.29-

Galvanised Reference

0.481 –

0.4243 –

0.4922 –

(%) Vt (m/s) Reference

40.96 NAV Manuwa and

42.33 NAV Manuwa and

20.61 NAV Kibar and

44.48 NAV Tavakoli et al.,

0.653 - Manuwa, 2000

0.6789 - Manuwa and

0.6876 NAV Manuwa and

0.19 – 0.33

0.601 - Manuwa, 2007

0.262 – 0.307

al., 1993

Afuye, 2004

Odubanjo, 2005

Ozturk, 2008

2009

al., 1993

Afuye, 2004

Odubanjo, 2005

Polat et al., 2006

Ozturk, 2008

Tavakoli et al., 2009

9.24 Polat et al., 2006

Bulk density

686.5 –

804.8 to

766.12 –

650.95 to 625.36

34.1 24.1 – 31.5 0.344 – 0.509 0.446 –

39.6 24.2 – 30.2 0.391 – 0.510 0.466 –

32.23 0.434 – 0.679 0.4245 –

0.3839 – 0.5774

Unspecified 8- 16 0.164 - 0.286 Kibar and

MC = moisture content, NAV= not available, PWLG = plywood parallel to grain, PWDG = plywood

Table 6. Effect of moisture content on angle of repose and coefficient of static friction of

29.93 0.28 – 0.326 0.287 –

Table 5. Effect of moisture content on density, sphericity, porosity and terminal velocity of

JS- 7244 8.7- 25.0 Desshpande et

Cultivars

TGX 1019-

TGX 1448- 2E 9.9 to

Unspecified 6.92-

Vt = terminal velocity

Cultivars

TGX 1019-

some soybean cultivars

TGX 1440-1E 10.5-

TGX 1448- 2E 9.9 to

Unspecified 6.92-

some soybean cultivars

TGX 1871- 5E 7.1- 43.7 23.43 –

2EB 6.7- 47.1 25.87 –

21.19

perpendicular to grain \*PLWD = plywood

MC range %(db)

TGX 1871- 5E 7.1- 43.7 1222.3 –

Unspecified 6.7- 15.3 1062.6 to

Unspecified 8- 16 983.33 –

21.19

MC= moisture content, NAV= not available

MC range %(db)

Seed density

935.7

1086.5

905.67

1147.86 to 1126.43

> Angle of repose (degree)

> > 32.45

Unspecified 6.7- 15.3 0.21 – 0.34 0.22 –

24.56 –

2EB 6.7- 47.1 1157 - 952 728.5 –

It can be seen that the number of soybean cultivars that have been developed around the world is numerous and can be better imagined. However, it appears that very little has been reported in literature concerning physical and engineering properties of such soybean cultivars. Nevertheless, it is obvious that post harvest options or technology are *sine qua non* in order to convert soybean seeds into quality food for human and animal in view of the quality of food nutrition available in the seeds.

#### **9. References**

ASAE.(2006a) Compression tests of food materials of convex shape. S368.4, 609- 616

