Agriculture Reference
In-Depth Information
Table 9.7.
Some chemical characteristics of coconut oils.
Parameter
Ordinary Coconut Oil
Virgin Coconut Oil
Coconut Paring Oil
Iodine value (Wijs)
7.6-10.0
5.0-10.0
15.5-16.9
Saponification value (mg KOH/kg)
>
250
>
250
>
250
Unsaponifiable matter (%)
0.80
0.20
0.8
Free fatty acid (%)
<
0.8
<
0.2
<
0.8
Fatty acid composition (%):
C
6:0
0.52
0.20
0.12
C
8:0
4.50
7.80
3.14
C
10:0
4.20
6.50
3.15
C
12:0
48.60
50.60
38.60
C
14:0
21.20
19.50
21.67
C
16:0
9.10
6.50
12.67
C
18:0
2.80
1.90
4.12
C
18:1
5.80
4.50
14.22
C
18:2
2.60
2.50
2.15
C
18:3
Trace
Trace
Trace
MCFA
1
(%)
57.82
65.10
45.01
LCSFA
2
(%)
33.10
27.90
38.46
1
MCFA, medium-chain fatty acid, C
6:0
to C
12:0
.
2
LCSFA, long-chain saturated fatty acid, C
14:0
to C
18:0
.
Source: SLS (2002); Marikkar et al. (2007a).
milk (Naka, 2006). When coconut milk is allowed to stand
for more than 10 hours under favorable conditions, the oil
naturally separates from the water and the proteins. It ba-
sically operates as a curdling process, and the top oil layer
needs to be scooped off using a ladle. In this method, heat
is not provided for the extraction of oil, but the filtered oil
is heated to remove residual moisture to ensure a prolonged
shelf life (Bawalan and Chapman, 2006).
Typically, the extracted oil is boiled to bring the moisture
content down. Though this method is operationally simple
and require low amount of capital investment, its output ca-
pacity is not sufficient for a large-scale operation (Silveira
et al., 2004).
Screw press expeller machines which operate at low-
temperature conditions may also be employed for VCO
extraction. However, the use of partially dehydrated ker-
nels in the screw press might cause choking or blockage
of the equipment. In order to overcome this problem, fresh
kernels can be pulverized and then dehydrated to a mois-
ture content of 3%. Dehydration is carried out using hot
air at a temperature of around 60
◦
C. As the dehydration is
carried out at a relatively low temperature to minimize the
burning effect, the process takes longer time. For oil ex-
traction, low-pressure microscrew press expellers specifi-
cally designed for low-temperature operation are used. Ac-
cording to the VCO production guideline, the extraction
temperature has to be maintained
≤
60
◦
C; if the extraction
temperature rises above 60
◦
C, it can impart some discol-
oration and odor to the oil, and furthermore, it may affect the
quality of defatted kernel residue due to burning (Baensch
et al., 2004).
VCO production by dry process
Dry processing is another method used for VCO produc-
tion. In contrast to the wet method, fresh kernel has to be
dehydrated partially using a low-temperature drying sys-
tem. First, kernels are shredded into fine particles and dried
under controlled temperature to reach moisture content of
10-13%. After partial dehydration, a simple “squeeze test”
is performed to check whether oil is oozing out from the ker-
nel. If a milky emulsion appears in the test, the kernel needs
to be further dried. When the dried shredded kernel passes
this test, it can be subjected to hydraulic press extraction
to extract oil. Since oil is extracted from a relatively high-
moisture raw material, the crude oil produced has higher
amount of water, which must be removed before storage.
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