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F. F. Akinola 1, O. O. Oguntibeju 2*, A. W. Adisa 1 and O. S. Owojuyigbe 31 Department of Biomedical Sciences, Ladoke Akintola University of Technology, Nigeria. 2 Department of Biomedical Sciences,Faculty of Health & Wellness Sciences, Cape Peninsula University of Technology, Bellville, 7535, South Africa. 3 Department ofScience Laboratory Technology, School of Applied Sciences, Federal Polytechnic Ede, Nigeria.*e-mail: [email protected], [email protected] properties of palm oil from different Nigerian oil palm local factories were determined at varying temperature. β-carotene contentswere determined by spectrophotometric method using Spectronic 21D spectrophotometer (digital) at wavelength of 440 nm. Refractive index wasdetermined by using Abbe refractometer while saponification value, acid value, free fatty acid contents, ester value, iodine value and peroxide valuewere determined by titrimetric method. Results showed that palm oil from Ogbomoso had the highest β-carotene contents, while palm oil from Ile-Ife had the least β-carotene content, which was reduced progressively as the experimental temperature increased.
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264 Journal of Food, Agriculture & Environment, Vol.8 (3&4), July-October 2010
www.world-food.net Journal of Food, Agriculture & Environment Vol.8 (3&4): 264-269. 2010
WFL PublisherScience and Technology
Meri-Rastilantie 3 B, FI-00980 Helsinki, Finland e-mail: [email protected]
Physico-chemical properties of palm oil from different palm oil local factories inNigeria
F. F. Akinola 1, O. O. Oguntibeju 2*, A. W. Adisa 1 and O. S. Owojuyigbe 3
1 Department of Biomedical Sciences, Ladoke Akintola University of Technology, Nigeria. 2 Department of Biomedical Sciences,Faculty of Health & Wellness Sciences, Cape Peninsula University of Technology, Bellville, 7535, South Africa. 3 Department of
Science Laboratory Technology, School of Applied Sciences, Federal Polytechnic Ede, Nigeria.*e-mail: [email protected], [email protected]
AbstractPhysico-chemical properties of palm oil from different Nigerian oil palm local factories were determined at varying temperature. β-carotene contents were determined by spectrophotometric method using Spectronic 21D spectrophotometer (digital) at wavelength of 440 nm. Refractive index was determined by using Abbe refractometer while saponification value, acid value, free fatty acid contents, ester value, iodine value and peroxide value were determined by titrimetric method. Results showed that palm oil from Ogbomoso had the highest β-carotene contents, while palm oil from Ile- Ife had the least β-carotene content, which was reduced progressively as the experimental temperature increased.
Key words: Palm oil, physical properties, chemical properties, stability, β-carotene, Nigeria.
Received 17 July 2010, accepted 28 October 2010.
IntroductionPalm oil which is orange-red to brownish or yellowish-red in colour is extracted from the mesocarp of fruits of oil palm tree (Elaeis guineensis). The oil palm fruit, a drupe, prolate spheroid in shape varies between 20 and 50 mm in length and could be as large as 25 mm in diameter is found in bunches that are attached to the crown of the tree through a stalk 1, 2. The pericarp comprises three layers, namely the exocarp (the skin), mesocarp (the outer pulp containing palm oil) and endocarp (a hard shell enclosing the kernel (the endosperm) which contains oil and carbohydrate reserves for the embryo. Fruit development starts at about two weeks after anthesis (WAA). Oil deposition in the endosperm starts at about 12 WAA and is almost completed by 16 WAA 3. It has been shown that during the 12 WAA, the endosperm and endocarp slowly harden and by 16 WAA, the endocarp is a hard shell enclosing a hard white endosperm (the kernel). Oil deposition in the mesocarp is believed to start at about 15 WAA and continues until fruit maturity at about 20 WAA. The fruits on a bunch do not ripen simultaneously owing to slight variation in the time of pollination. Fruits at the end of each spikelet ripen first and those at the base last. Fruits outside of the bunch are large and deep orange when ripe while the inner fruits are smaller and paler 4. Palmitoleic and linolenic acids are present in significant amounts in the early stages of lipid synthesis. These are typical chloroplast and membrane fatty acids, reflecting a high ratio of chloroplast and cellular synthesis to lipid synthesis and storage. However, these fatty acids are undetectable after 16 WAA, possibly because it is highly diluted by the accumulation of storage lipids. The immature mesocarp contains large amounts of chlorophyll which
decline by about 17 WAA, followed by a massive accumulation of carotenes as the fruit ripens. The immature green mesocarp also contains large amounts of sterols. It has been reported that as the fruit matures, the sterols decrease as a result of dilution by the huge amount of triglyceride synthesised 5. Like all oils, triglycerides are the major constituents of palm oil. More than 95% of palm oil consists of mixtures of triglycerides (glycerol molecules), each esterified with three fatty acids. During oil extraction from the mesocarp, the hydrophobic triglycerides attract other fat- or oil-soluble cellular components which represent the minor components of palm oil such as phosphatides, sterols, pigments, tocopherols, tocotrienols and trace metals. Other components in palm oil include monoglycerols, diglycerols and free fatty acids. The fatty acids are any of the class of aliphatic acids such as palmitic, stearic and oleic in animal and vegetable fats and oils. The major fatty acids in palm oil are myristic, palmitic, stearic, oleic and linoleic and most of the fatty acids are present as triglycerides. It has been reported that palm oil has saturated and unsaturated fatty acids in approximately equal amounts 5, 6. The minor constituents can be categorised into two groups. The first group consists of fatty acid derivatives, such as partial glycerides (e.g monoglycerols), phosphatides, esters and sterols while the second group comprises classes of compounds not related chemically to fatty acids and they are the hydrocarbons, aliphatic alcohols, free sterols, tocopherols, pigments and trace metals. Most of the minor components found in the unsaponifiable fraction of palm oil are sterols, higher aliphatic alcohols, pigments and hydrocarbons. However, the other minor components such as partial glycerides and phosphatides are saponifiable by alkaline
Journal of Food, Agriculture & Environment, Vol.8 (3&4), July-October 2010 265
hydroxide 7, 8. The partial glycerides do not occur naturally in significant amounts except in palm oil from damaged fruits and such oils would have undergone partial hydrolysis resulting in the production of free fatty acids, water and partial glycerides 9, 10. It should be noted that pigmentation of palm fruits is related to their stage of maturity and two classes of natural pigments occurring in crude palm oil are the carotenoids and the chlorophylls. The carotenoids are highly unsaturated tetraterpenes biosynthesized from eight isoprene units. Carotenoids are the precursors of vitamin A with carotene having the highest provitamin A activity. Palm oil has fifteen times more retinol equivalents than carrot and three hundred times more than tomato. Carotenes are sensitive to oxygen and light, and the oxidation of carotenes is accelerated by hydroperoxides generated from lipid oxidation, leading to discoloration and bleaching 7-9, 11. Over 90% of the world oil production is used as food. This has necessitated that the nutritional, physico-chemical properties and its fractions be adequately demonstrated. Also, since palm oil and its products have desirable physical and chemical characteristics for many food applications including margarine, it is therefore important to examine the physico-chemical properties of palm oil at different temperatures. This study was aimed at determining the physico-chemical properties such as beta-carotene contents, sapanification value, free-acid value, ester value, iodine value, specific gravity, refractive index and melting point of Nigerian palm oil obtained from different local factories in Ondo, Ogbomosho, Ikirun, Ife and Ede in the south-west region.
Materials and MethodsSample collection: Samples of palm oil were collected from different palm oil processing units at Ile-Ife, Ikirun, Ede, Ogbomoso and Ondo all in the western region of Nigeria. All chemicals and solvents used were of analytical grade purchased from Merck, Germany. Fatty acid methyl esters and triacylglycerol standards were obtained from Sigma Chemical Company, USA.
Determination of saponification value: Saponification value is the amount of alkali necessary to saponify a definite quantity of the sample (oil). It is expressed as the number of milligrams of potassium hydroxide (KOH) required for saponifying 1 g of the sample. The smaller the saponification number, the larger the average molecular weight of the tricylglycerol present in the oil 12.
Triacylglycerol + 3KOH (Glycerol + 3 fatty acids + 3 molecule of KOH) C
3H
5(C
17H
35COO)
3 + 3KOH � C
3H
5(OH)
3 + 3C
17H
35COOK
Two g of oil was weighed accurately and put into a conical flask containing 25 ml of 0.5 M alcoholic KOH. Reflux condenser was fitted to the flask containing the ionic solution and heated in a water bath for an hour swirling the flask frequently. Excess KOH was titrated hot with 0.5 M HCI using 1 ml of phenolphthalein (1%) solution. The saponification value was calculated from the difference between the blank and the sample titration.
Saponification value = (b – a) x 28.05/Weight of sample
where b = titre value of blank; a = titre value of sample; 28.05 = mg of KOH equivalent to 1 ml of 0.5 M HCI.
Determination of acid value and free acid content: The acid value is the number of milligrams of the potassium hydroxide necessary to neutralize the free acid in 1 g sample. The acid value is often a good measure of the breakdown of the triacylglycerol into free fatty acids, which has an adverse effect on the quality of many fats 13.
Ten ml of diethyl ether and 10 ml of n-propanol were mixed and 1 ml of phenolphthalein solution (1%) was added. Two g of oil was dissolved in the solvent and titrated with aqueous 0.1 M KOH, shaking constantly until a pink colour which persists for 15 s was obtained. The amount of KOH used was recorded. The procedure was repeated for the blank.
% Free fatty-acid = Acid value/2
Determination of ester value: Ester value is obtained by finding the difference between the saponification value (SV) and acid value (AV).
Determination of viscosity: For this study, specific gravity was used to measure viscosity. Specific gravity is the ratio of the mass of a given volume to the mass of an equal volume of water. The specific gravity decreases with increased temperature and decreases slightly as viscosity decreases for similar compositions. Ten ml of distilled water was weighed on weighing balance and
the weight was recorded as W1. Ten ml of the oil sample was also weighed on the weighing balance and the weight was recorded as W2.
Determination of iodine value: The iodine value of an oil or fat is defined as the weight of iodine absorbed by 100 g of the oil or fat. The glycerides of the unsaturated fatty acids (particularly of the oleic acid series) unite with a definite amount of halogen and the iodine value is therefore a measure of the degree of unsaturation. It is consistent for a particular oil or fat, however, the exact figure obtained depends on the particular technique employed. The greater the degree of unsaturation (i.e. the higher the iodine value), the greater the likelyhood that the oil or fat will become rancid by oxidation. The iodine value was determined by Wijs’ method. Palm oil was added and suitably weighed in a dry glass– stoppered bottle. The appropriate weight in gram of the palm oil to be used was calculated by dividing 20 by the highest expected iodine value, the stopper was inserted (previously moistened with potassium iodide solution) and allowed to stand in the dark for 30 min. Of potassium iodide (10%) 15 ml was added and mixed with 100 ml water. The solution was titrated with 0.1 ml thiosulphate solution using starch indicator just before the endpoint (titration = a ml). Blank was treated at the same time commencing with 100 ml of carbon tetrachloride (titration = b ml).
Acid value = Weight of sample used
Titre value x 5.61
Specific gravity = W1
W2
Iodine value = (b – a) x 1.269
Weight of sample
266 Journal of Food, Agriculture & Environment, Vol.8 (3&4), July-October 2010
Determination of beta-carotene: Two g of each oil sample was weighed into refine flask to form a paste. Of alcoholic KOH solution 25 ml was added and the mixture was heated in boiling water bath for 1 hour while shaking frequently. The mixture was cooled rapidly and 30 ml of water was added. The product obtained was transferred into a separation funnel. The solution was extracted three times with 25 ml of chloroform. Two g of anhydrous Na
2SO
4
was added to the extract to remove any traces of water. The mixture was then filtered into 100 ml volumetric flask and made up to mark with chloroform. Standard solution of beta-carotene, vitamin A of 0-50 Ug/ml was prepared by dissolving 0.003 of standard beta- carotene in 100 ml of chloroform. Gradient of different standard preparations was determined with reference to the absorbance from which average gradient was taken to calculate vitamin A from beta-carotene (Ug/100g). Absorbance of sample and standard were read spectrophotometrically at a wavelength of 440 nm.
Conversion:6 Ug of beta-carotene = 1 retinol equivalent 12 Ug of other biological active cartenoids = 1 retinol equivalent 1 retinol equivalent of vitamin A activity = 1 Ug of retinol 1 retinol equivalent = S. I (International Unit)
Determination of refractive index: Refractive index of oil samples was determined in triplicates at room temperature, 40°C and 60°C using Abbe refractometer.
Determination of peroxide value: One g of oil sample was weighed and poured into a dry 250 ml stoppered conical flask, flushed with inert gas. Ten ml of chloroform was added and the oil was dissolved by swirling. 15 ml of glacial acetic acid and 1 ml of fresh saturated aqueous potassium iodide solution were added. The flask was stoppered, shaken for 1 min and placed for 1 min in the dark. Thereafter 75 ml of water was added, mixed and the freed iodine was titrated with 0.002 M sodium thiosulphate solution using soluble starch solution (1%) as an indicator. The titre value was recorded as V. Blank determination (Vo) was also recorded.
where T = exact molarity of sodium thiosulphate solution.
Results and DiscussionCrude palm oil is a complex mixture consisting principally glycerides that represent the major component while carotenoids, tocopherols, tocotrienols, phytosterols and phosphatides represent the minor components. Red palm oil is produced from crude palm oil through a milder refining process that enables the retention of most of the carotenes and vitamins in the refined oil 14. Thus, red palm oil is considered as one of the richest plant source of carotenes which are precursor of vitamin A and vitamin E 15. Therefore, carotenes and vitamin E play important roles as antioxidants that may provide
oxidative stability to the oil. The stability of oil depends partly on the extent of deterioration during heating or storage. It is known that in living tissues, lipid constituents such as unsaturated fatty acids are sufficiently stable by natural antioxidants and enzymes that prevent lipid oxidation. However, once living tissues are removed from plant or animal materials, lipids deteriorate readily 16.Common quality deteriorations that may occur during oil processing are oxidation and hydrolysis. Criteria for assessing the extent of deterioration are necessary not only for scientific and industry interest but also because of health implications 17.The extent of physical and chemical changes occurring in palm oil is usually measured by chemical procedures that measure the primary and secondary products of lipid oxidation as peroxide value and carotene content. Free fatty acid content is measured because this is still one reliable parameter for food quality and it is used as indication of hydrolysis. It is also important to evaluate thermal stability of palm oil 14. In this study, it was observed that β-carotene content of palm oil decreased with increase in temperature and palm oil from Ogbomoso has the highest β-carotene content at the various temperatures of the experiment when compared with palm oil from other locations (Table 1). Palm oil from Ile-Ife has the least beta-carotene contents. This outcome is in agreement with Chen et al. 18, Lin and Chen 19 and Alyas et al. 14 who observed that beta-carotene content declined following increase in temperature. The difference in β-carotene content between palm oil from Ogbomoso and other locations reflect that palm oil from Ogbomoso is more stable and may thus be of a better quality. The primary products of lipid oxidation are hydroperoxides, therefore, the result of peroxide value gives a clear indication of oxidation 20. The peroxide value of palm oil at 120°C was less than the peroxide value at lower temperatures of the experiment (Table 2). The reduction of peroxide value at higher temperature could be attributed to the rapid decomposition of hydroperoxide to secondary oxidation product 21. It was observed that palm oil sample from Ondo has the highest peroxide value while sample from Ikirun has the least one. Peroxide value of various palm oil samples increased with increase in storage time. This is in line with the findings of Aidos et al. 22 and Skara et al. 23 who reported a significant increase in peroxide value with increasing storage time in different oils. By implication, it could be said that the peroxide value of the different palm oil samples reflected the state of oxidation and therefore the stability and quality of the oil. Oil samples from Ikirun had the highest iodine value at various temperatures while sample from Ogbomoso has the least iodine value (Table 3). Iodine value increased with increase in temperature. It has been reported that lowering the iodine value improves the stability and good yield of the liquid oil 21. Samples from Ondo had the highest specific gravity, while samples from Ikirun had the least specific gravity at various temperatures (Table 4). Specific gravity of the various palm oil samples decreased with increase in temperature. Sample from Ondo was greatly viscid. The amount of free fatty acid in palm oil is an indicator of the quality of the palm oil, and high level of free fatty acid is a presage of lipid oxidation 14. Table 5 shows that sample from Ondo has the highest free-fatty acid value while sample from Ile-Ife has the least free fatty acid value. Free-fatty acid value of the various
Gradient = Concentration of standard Absorbance of standard
Peroxide value = (V – Vo) T
Mx 103 mEq/kg
Beta-carotene equivalent = (Ug/100 g)
Absorbance × Gradient × Dilution factor
Weight of sample ×1
Journal of Food, Agriculture & Environment, Vol.8 (3&4), July-October 2010 267
Tit
re v
alu
e o
f sa
mp
le V
(ml)
P
ero
xid
e val
ue
P
alm
oil
loca
tio
n
M
Na 2
S2O
3
Wei
gh
t o
f
sam
ple
(g)
Tit
re v
alu
e
of
bla
nk
vo
l /m
l R
oo
m T
º C
40
º C
60
º C
120
º C
Ro
om
Tº C
40
º C
60
º C
120
º C
Oso
gb
o
0.0
02
1
.0
1.2
0
4.2
0
4.3
0
4.6
2
5.7
7
6.0
0
6.2
0
6.8
4
9.1
4
Ile-
Ife
0.0
02
1
.0
1.2
0
3.6
7
3.8
7
4.1
0
5.2
7
4.9
4
5.3
4
5.8
0
8.1
4
Og
bo
mo
so
0.0
02
1
.0
1.2
0
3.8
3
4.0
7
4.4
3
5.5
7
5.2
6
5.7
4
6.4
6
8.7
4
Ikir
un
0
.00
2
1.0
1
.20
3
.20
3
.40
3
.67
4.8
8
4.0
4
.40
4
.94
7
.36
On
do
0
.00
2
1.0
1
.20
4
.33
4
.57
4
.83
6.0
6
.26
6
.74
7
.26
9
.60
Tabl
e 2.
Per
oxid
e va
lue
of p
alm
oil.
Not
e: R
esul
ts a
re m
eans
of
at l
east
rep
lica
tes.
P
erox
ide
valu
e =
[(V
– V
o) x
M N
a 2S2O
3 x
103 ]
/[W
eigh
t of
sam
ple
(ME
q/kg
)]
Tabl
e 1.
Bet
a-ca
rote
ne e
quiv
alen
t of p
alm
oil
from
dif
fere
nt lo
catio
ns.
Not
e: R
esul
ts a
re m
eans
of
at l
east
thr
ee r
eplic
ates
.
Ab
sorb
ance
at
44
0 n
m
Bet
a ca
rote
ne
(Ug
/10
0g)
Pal
m o
il
loca
tio
n
Wei
ght
of
sam
ple
Gra
die
nt
Dil
uti
on
fact
or
Ro
om
Tº C
4
0º C
6
0º C
120
º C
Ro
om
Tº C
40
º C
60
º C
120
º C
Oso
gb
o
2.0
6
7.8
74
1
0.0
0
.96
4
0.9
59
0.9
53
0
.64
1
27
15
.62
68
3
25
45
.58
3
32
34
1.9
61
2
17
53
.61
7
Ile-
Ife
2.0
6
7.8
74
1
0.0
0
.95
8
0.9
56
0.9
49
0
.66
3
32
51
1.6
46
3
24
43
.77
2
32
20
6.2
13
2
14
82
.12
1
Og
bo
mo
so
2.0
6
7.8
74
1
0.0
0
.98
2
0.9
79
0.9
75
0
.66
5
33
32
6.1
34
3
32
24
.32
3
33
08
8.5
75
2
26
55
.97
9
Ikir
un
2
.0
67
.87
4
10
.0
0.9
79
0
.97
6
0.9
70
0
.65
5
33
22
4.3
23
3
31
22
.51
2
32
91
8.8
90
2
22
28
.73
5
On
do
2
.0
67
.87
4
10
.0
0.9
70
0
.96
6
0.9
60
0
.64
8
32
91
8.8
90
3
27
83
.14
2
32
57
9.5
20
2
19
91
.17
6
Pal
m o
il s
amp
les
titr
e v
alu
e (
a cm
3)
I
od
ine
val
ue
Pal
m o
il
loca
tio
n
Wei
gh
t
of
sam
ple
Bla
nk
tit
re
val
ue
b c
m3
Ro
om
Tº C
40
º C
60
º C
120
º C
Ro
om
Tº C
40
º C
60
º C
120
º C
Oso
gb
o
0.5
0
20
.20
1
.35
0
1.0
83
0
.88
3
0.4
33
4
7.8
4
48
.519
49
.03
7
50
.17
Ile-
Ife
0.5
0
20
.20
1
.11
6
0.8
67
0
.750
0
.37
7
48
.44
4
9.0
7
49
.36
5
0.3
1
Og
bo
mo
so
0.5
0
20
.20
1
.51
6
1.3
33
1
.100
0
.58
3
47
.42
4
7.8
8
48
.48
4
9.7
9
Ikir
un
0.5
0
20
.20
0
717
0
.41
7
0.2
50
0
.09
3
49
.45
5
0.2
1
50
.63
5
1.2
4
On
do
0.5
0
20
.20
1
.48
0
1.1
66
0
.90
0
0.4
13
4
7.5
1
48
.31
48
.98
5
0.2
2
Tabl
e 3.
Iodi
ne v
alue
of o
il.
Not
e: R
esul
ts a
re m
eans
of
at l
east
thr
ee r
epli
cate
s. I
odin
e va
lue
= [
(b –
a)
x 1.
269]
/Wei
ght
(kg)
of
sam
ple
Wei
gh
t o
f o
il s
amp
le 1
0 m
l =
W2
Sp
ecif
ic g
rav
ity =
W2/W
1P
alm
oil
loca
tio
n
Wei
gh
t of
10
ml
H2O
= W
1
Ro
om
Tº C
40
º C
60
º C
120
º C
Ro
om
Tº C
40
º C
60
º C
12
0º C
Oso
gb
o
9.7
8
8.9
70
8
.82
0
8.7
60
8
.59
7
0.9
17
0
.90
2
0.8
95
0
.87
9
Ile-
Ife
9.7
8
8.8
87
8
.75
7
8.7
17
8
.53
7
0.9
09
0
.89
0
0.8
91
0
.87
2
Og
bo
mo
so
9.7
8
8.8
67
8
.65
0
8.6
13
8
.51
3
0.9
07
0
.88
4
0.8
69
0
.87
0
Ikir
un
9
.78
8
.83
7
8.7
56
8
.74
3
8.3
47
0
.90
4
0.8
95
0
.89
4
0.8
53
On
do
9
.78
8
.98
8
.90
7
8.8
13
8
.76
0
0.9
18
0
.91
1
0.9
01
0
.89
6
Not
e: R
esul
ts a
re m
eans
of
at l
east
thr
ee r
eplic
ates
.
Tabl
e 4.
Spe
cifi
c gr
avity
of o
il.
268 Journal of Food, Agriculture & Environment, Vol.8 (3&4), July-October 2010
palm oil samples increase with increased temperature and agrees with the report of Alyas et al. 14
Saponification number is an indication of the amount of fatty saponifiable material in oil or fat. It gives information concerning the character of the fatty acids of the oil or fat and in particular regarding the solubility of their soaps in water. The higher the saponification number of the oil, the more soluble the soap that can be made from it 14. We reported that samples from Ondo had the highest saponification number or value while samples from Ikirun required least amount of alkali to saponify and thus would be adequate for soap making (Table 6). The saponification value for the various oil samples decreased with increased temperature, this implies that soaps are formed easily with increase in temperature. Table 7 shows that samples from Ondo had the highest ester value, while samples from Ikirun had the least ester value. Ester value of the various palm oil samples decreased with increased temperature. Table 8 shows that samples from Ondo had the highest melting point while samples from Ikirun had the least melting point. Our results also show that samples from Ondo had the highest refractive index at various temperatures (Table 9). Refractive index decreased with increased temperature of experimentation.
Conclusions and RecommendationsThis study showed that palm oil produced at different local factories in Western Nigeria display varied physico-chemical properties which tend to reflect the stability and quality of the palm oil. It also showed that temperature affects the physico- chemical properties of palm oil and β-carotene contents decreased with increasing temperature. This confirms that heating destroys the beta-carotene contents of palm oil and reduces its nutritive value as source of vitamin A. Heating of the various palm oil samples accelerated the formation of peroxide and this increased with prolonged heating. We did not assess the relationship between storage time and physico-chemical changes of the different palm oil samples. The study was limited to the Western part of Nigeria, therefore the outcome of the study cannot be said to be a true representative of palm oil from all parts of Nigeria. Further studies that will investigate the effects of storage and processing procedures on the components of palm oil are recommended.
Tit
re v
alu
e (c
m3)
Aci
d v
alu
e
% f
ree
fatt
y a
cid
= A
cid
val
ue/
2P
alm
oil
loca
tion
Wei
gh
t o
f
sam
ple
(mg)
Ro
om
Tº C
40
º C
60
º C
120
º C
Ro
om
Tº C
4
0º C
6
0º C
120
º C
Ro
om
Tº C
4
0º C
6
0º C
120
º C
Oso
gb
o
2.0
0
.823
0
.88
0
10
02
6
1.3
6
2.3
09
2
.46
8
2.8
78
3
.81
5
1.1
55
1
.23
4
1.4
39
1
.90
8
Ile-
Ife
2.0
0
.483
0
.63
3
0.7
16
1
.03
7
1.3
54
1
.77
5
2.0
90
8
2.9
08
0
.67
7
0.8
87
1
.004
1
.45
4
Og
bo
mo
so
2.0
0
.550
0
.68
3
0.8
33
1
.23
3
1.5
43
1
.91
6
2.3
37
3
.45
9
0.7
71
0
.95
7
1.1
68
1
.72
9
Ikir
un
2
.0
0.3
26
0
.40
7
0.6
50
1
.10
0
0.5
52
1
.14
2
1.8
23
3
.08
6
0.2
75
0
.57
1
0.9
11
1
.54
3
On
do
2
.0
0.9
33
1
.06
6
1.2
50
1
.81
2
2.6
17
2
.99
0
3.5
05
5
.08
3
1.3
09
1
.49
5
1.7
53
2
.54
1
Tabl
e 5.
Aci
d va
lue
and
free
fatty
aci
d va
lue
of o
il.
Not
e: R
esul
ts a
re m
eans
of
at l
east
thr
ee r
eplic
ates
. Aci
d va
lue
= (
Titr
e va
lue
x 5.
61)/
Wei
ght
of s
ampl
e
Sam
ple
tit
re v
alu
e a
(cm
3)
S
apo
nif
icat
ion
val
ue
(m
g K
OH
/g)
Pal
m o
il
loca
tion
Wei
gh
t o
f
sam
ple
(g)
Val
ue
b
(cm
3)
Ro
om
Tº C
40
º C
60
º C
120
º C
Ro
om
Tº C
40
º C
60
º C
120
º C
Oso
gb
o
2.0
2
7.9
0
13
.25
1
3.4
5
13.6
5
14
.25
20
4.7
7
20
2.6
6
19
9.8
6
191
.44
Ile-
Ife
2.0
2
7.9
0
13
.82
5
13
.90
1
4.1
5
14
.65
19
7.4
0
19
6.3
5
19
2.8
4
185
.85
Og
bo
mo
so
2.0
2
7.9
0
14
.42
5
13
.55
1
3.8
5
14
.50
20
3.0
1
20
1.2
6
19
7.0
5
187
.94
Ikir
un
2
.0
27
.90
1
3.9
0
14
.05
1
4.3
5
14
.75
19
6.3
5
19
4.2
5
19
0.0
4
184
.43
On
do
2
.0
27
.90
1
3.1
25
1
3.2
5
13.4
5
13
.95
20
7.2
2
20
5.4
7
20
2.6
6
195
.65
Tabl
e 6.
Sap
onif
icat
ion
valu
e of
oil.
Not
e: R
esul
ts a
re m
eans
of
at l
east
thr
ee r
eplic
ates
. Sa
poni
fica
tion
valu
e (m
g K
OH
/g)
= [
(b –
a)
x 28
.05]
/Wei
ght
(kg)
of
sam
ple
Journal of Food, Agriculture & Environment, Vol.8 (3&4), July-October 2010 269
References1AOCS 1997. Sampling and analysis of commercial fats and oils. Am. Oil
Chemists Official Methods (AOCS) Press, Champaign, Illinois, USA. 2Orji, M. U. and Mbata, T. I. 2008. Effect of extraction methods on the
quality and spoilage of Nigerian palm oil. Afri. J. Biochem. Res. 2(9):192-196.
3Idris, A. I. and Suria, M. S. A. 2000. Food uses of palm and palm kernel oils. In Basiron, Y., Jalani, B. S. and Chan, K. W. (eds). Advances in Oil Palm Research. Malaysia Palm Oil Board Kuala Lumpur, Malaysia, pp. 968-1035.
4Corley, R. H. V. 1976. The genus Elaeis: In Corley, R. H. V., Hardon, J. J. and Wood, B. J. (eds). Oil Palm Research. Elsevier Scientific Publ. Co., Amsterdam, Netherlands, pp. 3-5.
5Siew, W. L. 2000. Chemical and physical characteristics of palm oil and palm kernel oils and their crystalisation behaviour. In Zainon, M. S. and Johari, M. (eds). Lectures on Palm Oil and Its Uses. MPOB, Bangi, pp. 64-85.
6United States Department of Agriculture 2004. Agricultural Statistics. pp. 48-51.
7Akanni, M. S., Adekunle, S. A. and Oluyemi, E. A. 2005. Physico- chemical properties of some non-conventional oil seed. J. Food Technol. 3:177-181.
8Adelaja, J. O. 2006. Evaluation of Mineral Constituents and Physico- chemical Properties of Some Oil Seed. MSc. Industrial Chemistry, University of Ibadan, Ibadan.
9Farombi, E. O. 2003. African indigenous plants with chemotherapeutic potentials and biotechnological approach to the production of bioactive prophylactic agents. Review. Afri. J. Biotech. 2(2):662-671.
10Dawodu, F. A. 2009. Physico-chemical studies on oil extraction processes from some Nigerian grown plant seeds. EJAFChe 8(2):102-110.
11Oguntibeju, O. O., Esterhuse, A. J. and Truter, E. J. 2009. Red palm oil: Nutritional, physiological and therapeutic roles in improving human wellbeing and quality of life. Brit. J. Biomed. Sci. 66(4):216-222.
12Petrauskaite, V., De Greyt, W., Kellens, M. and Huyghebaert, A. 1998. Physical and chemical properties of trans-free fats produced by chemical interesterification of vegetable oil blends. J. Am. Oil. Chemists Soc. 75(4):489-491.
13MPOB 2005. MPOB Test Methods. MPOB, Bangi, 395 p. 14Alyas, S. A., Abdulah, A. and Idris, N. A. 2006. Changes of beta-
carotene content during heating of red palm olein. J. Oil Palm Res. (Special Issue), pp. 99-102.
15Nagendran, U. R., Unnithan, Y. M., Choo, Y. M., Sundram, K. 2000. Characteristics of red palm oil, a carotene and vitamin E rich refined oil for food uses. Food and Nut. Bull. 21(2):189-194.
16Krings, U. and Berger, R. G. 2001. Antioxidant activity of some roasted foods. Food Chem. 72:223-229.
17Anon. 2004. Research and development for food safety in palm oil. Global Oils and Fats Mag. 1(2):15-16.
18Chen, H. E, Peng, H. Y. and Chen, B. H. 1996. Stability of carotenoids and vitamin A during storage of carrot juice. Food Chem. 57:497-503.
19Lin, C. H. and Chen, B. H. 2005. Stability of carotenoids in tomato juice during storage. Food Chem. 90:837-846.
20Suja, K. P., Abraham, J. T., Thamizah, S. N., Jayalekshmy, A. and Arumughan, C. 2004. Antioxidant efficacy of sesame cake extract in vegetable oil production. Food Chem. 84:393-400.
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22Aidos, I., van der Padt, A., Remko, B. and Luten, M. 2001. Upgrading of Maatjies herring by-products: Production of crude fish oil. J. Agri. & Food Chem. 49:3697-3704.
23Skara, T., Sivertsvik, M. and Birkeland, S. 2004. Production of salmon oil from filleting by-products effects of storage condition and content of 3 polyunsaturated fatty acids. J. Food Sci. 69:417-421.
Pal
m o
il l
oca
tion
s E
ster
val
ue
at r
oo
m T
º C
Est
er v
alue
at 4
0º C
E
ster
val
ue
at 6
0º C
E
ster
val
ue
at 1
20
º C
Oso
gbo
203.6
15
201.4
26
198.4
21
189.5
32
Ile
– I
fe
196.7
23
195.4
63
191.8
36
184.3
76
Ogbom
oso
202.2
39
200.3
03
195.8
82
186.2
11
Ikir
un
196.0
75
193.6
79
189.1
29
182.8
87
Ondo
205.9
1
203.9
75
200.9
07
193.1
09
Not
e: R
esul
ts a
re m
eans
of
at l
east
thr
ee r
eplic
ates
.
Tabl
e 7.
Est
er v
alue
(sap
onif
icat
ion
valu
e –
acid
val
ue) o
f oil.
Pal
m o
il l
oca
tion
s M
elti
ng p
oin
t
Oso
gb
o
45
º C
Ile
– I
fe
43
º C
Og
bo
mo
so
46
º C
Ikir
un
4
1º C
On
do
4
8º C
Tabl
e 8.
Mel
ting
poin
t of
oil.
Pal
m o
il l
oca
tion
s A
t ro
om
Tº C
4
0º C
6
0º C
1
20
º C
Oso
gb
o
1.4
56
0
1.4
51
7
1.4
49
7
1.4
43
1
Ile
– I
fe
1.4
62
0
1.4
58
8
1.4
52
3
1.4
43
3
Og
bo
mo
so
1.4
49
1
1.4
48
3
1.4
43
0
1.4
27
2
Ikir
un
1
.43
90
1
.43
84
1
.43
40
1
.42
12
On
do
1
.46
37
1
.46
21
1
.46
01
1
.45
45
Tabl
e 9.
Ref
ract
ive
inde
x of
oil.
