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International Journal of Scientific Research in Environmental Sciences (IJSRES), 1 (11), pp. 337-343, 2013

Available online at http://www.ijsrpub.com/ijsres

ISSN: 2322-4983; 2013 IJSRPUBhttp://dx.doi.org/10.12983/ijsres-2013-p337-343

Full Length Research Paper

Engineering Properties of Bitter Kola Nuts and Shell As Potentials for DevelopmentProcessing Machines

Rotimi Davies1*, Usman Shehu Mohammed2

1Department of Agricultural and Environmental Engineering, Niger Delta University, Wilberforce Island, Amassoma, Bayelsa

State,Nigeria2Department of Agricultural Engineering, Ahmadu Bello University, Zaria, Kaduna State, Nigeria

*Correspondence:rotimidavies@yahoo.com

Received 09 September 2013; Accepted 24 October 2013

Abstract. The knowledge of engineering properties of any biomaterial is fundamental. It facilitates the design and

development of equipment for harvesting, handling, conveying cleaning, delivering, separation, packing, storing, drying,mechanical oil extraction and processing of agricultural products. The study was conducted to investigate the physical,mechanical and frictional properties of bitter kola nut and shell, namely, axial dimensions, 1000 unit mass, arithmetic mean

diameter, geometric mean diameter, surface area, sphericity, aspect ratio, bulk density, true density, porosity and angle ofrepose and coefficient of static friction were determined using standard methods. The engineering properties of bitter kola nut

and shell were investigated at the moisture content of 20.8% and 23.1% dry basis respectively. The result obtained from thestudy revealed mean length, width, thickness, arithmetic and geometric diameter, sphericity, surface area and 1000unit mass

ranged from 21.90-24.13 mm, 11.65-12.96 mm, 12.07-19.10 mm,15.21-22.03 mm, 14.55- 18.14 mm, 65- 75%, 447.9-1033.9mm and 3087.05- 3350.12 g respectively. The coefficient of static friction was determined for four frictional surfaces, namely,

fibreglass, plywood, galvanized steel and rubber. The coefficient of static friction was the highest for bitter kola nut and shellon rubber surface and lowest for fiberglass.

Key words: bitter kola, engineering properties, moisture content, axial dimension.

1. INTRODUCTION

Bitter kola otherwise known as (Garcinia kola) is an

important medicinal crop of the tropics. It regarded as

one of the most important crops used in treating

purgative, antiparasitic, antimicrobial, treatment

of bronchitis, throat infections and prevention of

relieve colic, cure head or chest colds and relieve

cough in the continent of Africa. For bitter kola nut

and shell, whose medicinal and economic potential are

increases growing fast, there is much need to develop

appropriate technology and equipment for various unitoperations and to minimize the drudgery and improve

the sanitation of the processing operations. This

required the knowledge of physical properties of the

crop. The knowledge of engineering properties of

bitter kola nut and shell like any other biomaterial is

fundamental because it facilitates the design and

development of equipment for harvesting, handling,

conveying cleaning, delivering, separation, packing,

storing, drying, mechanical oil extraction and

processing of agricultural products, their physical

properties have to be known (Aviara et al., 2005;

Davies, 2011). Presently, the equipment used in

processing bitter kola nut and shell have been

generally design without taken into cognizant the

physical properties of bitter kola nut and shell which

include the size, mass, bulk density, true density,

sphericity, porosity, coefficient of static friction and

angle of repose and resultant systems leads to

reduction in working efficiency and increased product

losses (Manuwa and Afuye, 2004; Razari et al., 2007).

The engineering properties have been studied for

various agricultural products by other researchers such

as almond nut and kernel (Aydin, 2003), soybean

(Manuwa and Afuye, 2004 Davies and El-Okene,

2009), African nutmeg (Burubai et al., 2007), caper

fruit (Sessiz et al., 2005) cocoa bean (Bart-plange and

Baryeh, 2002), jatropha seed and karanja kernel(Pradhan et al., 2008), gbafilo fruit and kernel and

cowpea (Davies and Zibokere, 2011), pigeon pea

(Shepherd and Bhardwaj (1986), locust bean seed

(Ogunjimi et al., 2002), wheat (Tabatabaefa, 2003)

and pistachio nut and its kernel (Razari et al ., 2007)

and groundnut grain (Davies, 2009). Investigation was

therefore carried out to determine the engineering

properties of bitter kola nut and shell such as axial

dimension, geometric and arithmetic mean diameter,

sphericity, surface area, unit mass, 1000 grain mass,

true volume, true and bulk densities, porosity, angle of

repose and static coefficient of friction of bitter kola

nut and shell in order to develop appropriate

equipment that will alleviate laborious nature

experience in processing the crop.

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2. MATERIALS AND METHODS

The bitter kola was bought from Abuloma market,

Port Harcourt in Rivers state, Nigeria on 21th June,

2012. The sample was selected and cleaned manually

to ensure that the bitter kola nut and shell were free of

dirt, broken ones and other foreign materials. The

bitter kola nut and shell were kept in the room

temperature for five days. The experiments were

conducted for the bitter kola at the moisture content

levels of 20.1% for bitter kola nut and 23.8 % for

bitter kola shell dry basis respectively. Three samples

each weighing 15 g was placed in an oven set at 103

2C for 24 hours. Thus, seeds samples of the desired

moisture level were prepared by adding calculated

amount of distilled water and sealed in separate

airtight polythene bags. The seed was kept inrefrigerator at a temperature of 5 for one week to

enable the moisture to distribute uniformly (Davies

and El- Okene, 2009). To prepare bitter kola nut and

shell with higher moisture contents, the required

amount distilled water was calculated from the

following equation and added to the samples

(Kashaninejad et al., 2005):

=

1

21

12

100 M

MMWW

(1)

where, W1 and W2 are mass of the sample anddistilled water (g), and M1andM2 are initial and final

moisture contents (% d.b.) respectively.

For this experiment, 100 bitter kola nut and shell

were randomly selected, the length, width and

thickness and mass of bitter kola nut and shell were

measured using a micrometer screw gauge with a

reading of 0.01 mm. The average diameter was

calculated by using the arithmetic mean and geometer

means of the three axial dimensions. The arithmetic

mean diameter and geometric mean diameter of the

bitter kola nut and shell were calculated according to

Galedar et al., 2008 and Mohsenin, 1980.The sphericity was calculated based on Koocheki

et al. 2007 and Milani 2007. The surface area was

calculated according to McCabe et al ., (1986). The

aspect ratio was determined according to Maduako

and Faborode, (1990).The volume was calculated as

cited by Miller (1987). The 1000 unit mass was

determined using precision electronic balance to an

accuracy of 0.01g. 50 randomly selected bitter kola

nut and shell were weighed and multiplied by 20. The

reported value was a mean of 20 replications. The

bulk bitter kola nut and shell were put into a container

with known mass and volume (500ml) from a height

of 150 mm at a constant rate Bulk density was

calculated from the mass of bulk seeds divided by the

volume containing mass (Garnayak et al., 2008). The

true density was determined using the unit values of

unit volume and unit mass of individual seed and

calculated using the following relationship by Li et al .

(2008). The porosity of the bulk bitter kola nut and

shell was computed from the values of the true density

and bulk density of the seed by using the relationship

given by Mohsenin (1980).

The static coefficient of friction for bitter kola nut

and shell determined with respect to four test surfaces

namely plywood, galvanized iron sheet, rubber sheet

and fibreglass. A glass box of 150mm length, 100mm

width and 40mm height without base and lid was

filled with sample and placed on an adjustable tilting

plate, faced with test surface. The sample container

was raised slightly (5 10 mm) so as not to touch the

surface. The inclination of the test surface was

increased gradually with a screw device until the boxjust started to slide down and the angle of tilt was

measured from a graduated scale. For each replicate,

the sample in the container was emptied and refill

with a new sample (Joshi et al., 1993). The static

coefficient of friction was calculated based on this

equation, (Mohsenin, 1980).

The static angle of repose with the horizontal at

which the material will stand when piled. This was

determined using topless and bottomless cylinder of

0.15 m diameter and 0.25 m height. The cylinder was

placed at the centre of a raise circular plate having a

diameter of 0.35m and was filled with bitter kola nutand shell. The cylinder was raised slowly until it

formed a cone on a circular plane. The height of the

cone was measured and the filling angle of repose was

calculated based on the following relationship

established by (Karababa, 2006 and Kaleemullah and

Gunaseka, 2002).

3. RESULTS AND DISCUSSIONS

Some engineering properties such as axial

dimensions, arithmetic and geometric mean diameter,

sphericity, volume, 1000 unit mass and surface area ofbitter kola nut and shell investigated at moisture

content are presented in Table 1.These parameters

were investigated at moisture content 20% for bitter

kola seeds and 23.7% for dry basis. The mean length,

width and thickness of bitter kola seeds ranged

between 17.20-26.51 mm and 32.66-22.56, 9.43-14.73

mm and 12.09-16.31, 10.50-13.73 mm and 17.74-

22.10 respectively. The corresponding mean size of

the fresh dura palm kernel were length, width and

thickness were found to be 30.25 mm, 19.94 mm and

15.66 mm, respectively (Owolarafe et al., 2007). The

corresponding values of axial dimensions for palm

kernel (Dura variety), average length, width and

thickness ranged from 26.50 - 44.00 mm, 16.50 -

28.00 mm and 21.50 -34.50mm respectively

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(Mijinyawa and Omoikhoje, 2005). The parameters

are essential for the design of appropriate equipment

for processing such as cleaning, sorting, packaging

and storage processes. The values of the measured

parameters and the corresponding values indicated

that the machines required for utilization and

processing these products would be different. The

mean geometric and arithmetic mean diameter of

bitter kola seeds ranged from 12.38 to 18.15 mm and

17.46 to 23.69 mm and11.94 to17.28 mm and 16.91 to

22.75 mm respectively. The geometric and arithmetic

mean diameters of palm fruit ranged from 21.36 to

29.23 mm and 20.80 to 27.80 mm (Davies, 2012). The

corresponding values for watermelon as reported

Koocheki et al. (2007) were 6.89 and 8.24mm for

Kolaleh, 8.37 and 10.79 mm for Ghemez and 7.61 and

9.28 mm for Sarakhsi at moisture content of 5.02,4.75 and 4.55% wet basis.

The mean surface area of bitter kola nut and shell

were 447.9mm and 898.4mm.Themean surface area

of gbafilo fruit and kernel ranged from 1584.80 to

2455.90 mm and 737.37 to 1378.90 mm (Davies and

Zibokere et al., 2011). The mean sphericity value

ranged from 65% to 68% for bitter kola nut and 69%

to 75% for bitter kola shell. The sphericity was

observed forC. lunatus, 53%, C. edulis, 47% and C.

vulgaris, 45% (Davies and Zibokere et al., 2011). The

mean sphericity of bitter kola shell and nut were

significantly different (P

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Table 1: Physical properties of bitter kola nut and shellProperties Sample no Bitter kola nut Bitter kola shell

Maximum Minimum Mean Maximum Minimum Mean

Length (mm) 100 26.51 17.20 21.90 32.66 22.56 24.13

Width (mm) 100 14.73 9.43 11.65 16.31 12.09 12.96

Thickness(mm) 100 13.73 10.50 12.07 22.10 17.74 19.10

Arithmeticmean

diameter(mm)

100 18.15 12.38 15.21 23.69 17.46 22.03

Geometricmean

diameter(m

m)

100 17.28 11.94 14.55 22.75 16.91 18.14

Sphericity(%) 100 65 69 68 69 74 75

1000-untmass (g)

50 4200.35 3087.02 3252.6

1

4350.16 3112.74 3305.2

7

Surfacearea(mm2)

100 938.2 447.9 665.2 1626.2 898.4 1033.9

Volume(mm3)

100 2701.28 891.83 1612.62 6164.78 2533.81 3127.88

Aspect ratio(%)

100 55.56 54.83 53.19 49.94 53.59 53.7

Table 2: Gravimetric and frictional properties bitter kola fruit and nut at moisture at 8.3% dry basisProperties Bitter kola fruit Mean (S.E.M) Bitter kola shell Mean (S.E.M)

True density (kgcm-3) 946.5324.09 873.6143.17b

Bulk density (kgm-3) 690.506.23 6214.20Porosity (%) 35.600.97 40.701.21

Angle of repose() 33.50.07 21.90.04

Fibreglass 0.350.02 0.290.02Galvanised iron sheet 0.460.01 0.330.01

Plywood sheet 0.510.02 0.390.07Rubber sheet 0.530.02 0.430.03Fx Vertical fracture force (N) 1953.76 210.19

Fy Horizontal fracture force(kN)

321.610.49 34.01.05

S.E.M- Standard error of means.

4. CONCLUSION

The following conclusions are drawn from the

investigation on the some engineering properties of

bitter kola nut and shell at moisture content of 6.33%

and 5.21% dry basis respectively:

(1) The physical properties of bitter kola nut andshell such as mean length, width, thickness, arithmetic

and geometric mean diameter, sphericity, surface area,

1000unit mass and aspect ratio were investigated; (2)

The mean porosity, true and bulk densities, angle of

repose was investigated for the bitter kola nut and

shell. The obtained results were 35.60, 40.70, 946.53,

873.61, 690.50, 621 kg/m3 kg/m3 and 29.3-36,

respectively; (3) The coefficient of static friction of

bitter kola nut and shell was determined for four

different surfaces namely, fibreglass, plywood,

galvanized iron sheet and rubber. The highest

coefficient of static friction for bitter kola nut andshell corresponds to rubber surface.

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Dr. Rotimi Davies is a lecturer in the Department of Agricultural and Environmental

Engineering, Niger Delta University (NDU), Wilberforce Island, Amassoma, Bayelsa State,Nigeria. He is a certified Engineer, a registered member of the Council for the Regulation of

Engineering in Nigeria (COREN). Dr. Rotimi Davies bagged his B.Sc. (Hons) and mastersdegrees in Agricultural Engineering from the premier University of Ibadan, Ibadan, Nigeria. He

later obtained his doctorate degree in Agricultural Engineering from the renowned Ahmadu BelloUniversity (ABU), Zaria, Kaduna State, Nigeria. His areas of specialization are Bio-energy, Crop

Processing and Storage Engineering. Dr. Rotimi Davies is a dynamic and an outstanding Engineerwho has published many research articles in international journals. Dr. Rotimi Davies had held quite a

number of administrative positions but presently, he is the Staff and Undergraduate Students Seminarsand Projects Coordinator of the Department of Agricultural and Environmental Engineering at NDU.

Dr. Usman Shehu Mohammed is an Associate Professor in the Department of Agricultural

Engineering, Ahmadu Bello University (ABU), Zaria, Kaduna State, Nigeria. He is a certifiedEngineer, a registered member of the Council for the Regulation of Engineering in Nigeria (COREN).

He obtained his first, masters and doctorate degrees in Agricultural Engineering from the prestigiousABU in 1984, 1999 and 2001 respectively. Dr. Mohammed specializes on Farm Power and Machinery.

He is an astute lecturer and researcher who has published numerous referred articles in local and

international journals. His hobbies are basketball, squash and athletics. Dr. Mohammed had heldseveral administrative positions at ABU but presently, he is the Departmental Postgraduate Coordinator

of Agricultural Engineering.