Agriculture Reference
In-Depth Information
dilauryl myristin (18%); the remaining TAG molecules are
less than 12% (Tan and Che Man, 2000). The fatty acid
distributional pattern within the TAG molecules of coconut
oil is nutritionally important. The pattern of the fatty acid
distribution might vary due to varietal differences, maturity
of the kernel, and the method of extraction (Table 9.7).
In coconut, the kernel formation in the developing drupe
may start at the sixth month of maturity. The oil content of
the 6-month-old nut is about 1% (wet basis), while that of a
12-month-old nut is about 34% (wet basis). The increase in
the oil content of the developing kernel during the interval
between 7 and 8 months is about 300% (Marikkar et al.,
2004). As this is the right maturity stage for harvesting co-
conut for drinking purpose (Ranasinghe et al., 2003), the
fatty acid composition of the soft, spongy kernel is nutri-
tionally important. The oils extracted from tender nuts at
the age of 6 and 7 months are found to be rich in oleic
and linoleic acids (Table 9.9). Hence utilization of the soft,
spongy kernel of the tender nut after extracting the water
would be beneficial for new product development. As for
the lauric acid, there is a steady increase, while palmitic,
oleic, and lenoleic acid tend to decrease (Marikkar et al.,
2004). The proportion of myristic acid in the oil remains
almost the same through kernel development. When co-
conut reaches its full maturity, lauric acid tends to become
the most dominant fatty acid in the oil extracted out of it
(Table 9.9).
Commercially, three types of coconut oils are marketed:
ordinary coconut oil, which is extracted from copra; co-
conut paring oil; and VCO extracted from the kernel out
of brown testa. They might vary slightly in their fatty acid
composition (Table 9.7), but in all three types, the medium-
chain fatty acids (MCFA), C
6:0
to C
12:0
, are predominant.
Of the MCFA group of fatty acids, lauric acid esterifi-
cation takes the predominance, while the esterification of
caproic (C
6:0
), caprylic (C
8:0
), and capric (C
10:0
) acids is
less. Among the three different types of coconut oils, the rel-
ative percentage of MCFA varies from 45.01% to 65.10%,
with VCO having the highest amount. On the other hand,
the highest proportion of long-chain saturated fatty acids
(LCSFA) is found in the coconut paring oil (38.46%), while
its amount is lowest (27.9%) in VCO (Table 9.7).
Varietal differences also have some influence on the com-
position of coconut oil. Among the different cultivars of
coconut introduced in Sri Lanka, the relative percentage
of MCFA varies from 55% to 68%, 'CRIC 60' (
Ta l l
×
Tall)
having the highest amount. On the other hand, the
highest amount (34%) of LCSFA is found with the cultivar
'CRIC 60' (
Dwarf Green
×
Ta l l
), while its amount is lowest
(26.5%) in 'CRIC 60' (
Ta l l
Tall)
(Marikkar et al., 2004).
Apart from nutritional benefits, MCT present in coconut
oil is also reported to impart a wide range of positive health
benefits. On the basis of the research work reported in the
1970s by Kabara (1978, 1979), lauric acid in its mono-
glyceride form (monolaurin) is known to display antibac-
terial, antiviral, and antifungal activities. The antimicro-
bial activities of dilaurin and trilaurin were significantly
lower when compared to that of monolaurin. These are
established based on the fact that MCFA with 6 to 12 car-
bons possessed significant activity against gram-positive
bacteria but not against gram-negative types. They were
also found to be active against lipid-coated viruses as well
as fungi and protozoa. Some clinical trials have shown
that monolaurin from coconut oil may also possess some
×
Table 9.9.
Percentage variation of fatty acid composition of oil from cultivar Tall
×
Tall at different
stages of maturity.
Maturity Stage (Months)
Fatty Acid
6
7
8
9
10
11
12
Caprylic (C
8:0
)
2.5
5.6
10.3
8.9
9.1
8.4
8.2
Capric (C
10:0
)
1.4
3.2
6.3
6.6
6.3
6.6
6.8
Lauric (C
12:0
)
24.3
31.5
45.9
51.7
54.4
56.4
56.8
Myristic (C
14:0
)
18.3
20.4
18.7
18.9
18.9
18.0
19.0
Palmitic (C
16:0
)
21.6
14.8
8.3
6.7
5.3
4.9
4.7
Stearic (C
18:0
)
1.2
1.6
2.0
2.0
1.7
1.7
1.6
Oleic (C
18:1
)
18.7
16.3
6.4
3.7
2.8
2.8
2.8
Linoleic (C
18:2
)
12.0
6.6
2.0
1.4
1.4
1.2
1.2
Source: Marikkar et al. (2004).
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