F&N Bulletin Vol 23 No 1b - United Nations University

Palm oil
will be less absorbed and therefore contribute less
to caloric intake and serum triacylglycerols. Assuming
that all the unsaturated fatty acids at the 1- and
3-positions in palm oil are preferentially absorbed
while the saturated fatty acids from these same positions
are excreted as salts, then only 8% of saturated
fatty acids from the 2-position will be absorbed, an
ideal situation to enhance the nutritional attribute
of palm oil. Studies indicate that the fatty acids in
the 2-position of the triacylglycerols have been highly
conserved in the digestive process [10–13]. Research
has also suggested that dietary cholesterol needs to be
re-esterified with unsaturated fatty acids before it is
incorporated into chylomicrons and transported by
intestinal lymph. Therefore, palm oil fatty acids will be
expected to contribute less to the absorption of dietary
cholesterol already in the bloodstream.
Technical performance
Quality must also be considered in the performance
of the oil during processing. For example, during
13
frying at 180°C, polyunsaturated oil undergoes extensive
oxidation, giving rise to oxidized products and
dimeric/oligomeric compounds. Similarly, ready biological
oxidation of polyunsaturated molecules leads
to reactive free oxy-radicals, which are harmful to
human cells and genetic material. Although the polyunsaturated
oil can be stabilized by hydrogenation
to produce more saturated material, partial hydrogenation
inevitably produces trans fatty acids, which
have been shown to cause two undesirable effects:
raising the “bad” low-density-lipoprotein (LDL) cholesterol
and lowering the “good” high-density lipoprotein
(HDL) cholesterol, both effects being considered
harmful to the heart in the long term. Therefore, an oil
with high oxidative stability, such as palm oil, which
does not require hydrogenation in the majority of
applications, would be the preferred choice over other
vegetable oils. Furthermore, refined palm oil provides
an organoleptic bland flavor ideally suited to enhance
the various flavors of foods. A wide range of solid
fat products, e.g., margarine and shortenings, are
also needed in the marketplace, and this requirement
means that polyunsaturated oils need to be partially
TABLE 1. Positional distribution of fatty acids in triacylglycerols in oils and fats
Fatty acid (mol%)
Major
triacyl-
Oil Positions 16:0 16:1 18:0 18:1 18:2 18:3 20:0 20:1 22:0 22:1 24:0 glycerols a
Virgin palm oil 1, 2, 3 44.3 4.6 39 10.5 POP, POO
2 11.0 2.0 65.0 22.0 — — — — — — PLO, PLP b
Palm olein 2 4.3 65.9 29.8
Olive oil 1 13.1 0.9 2.6 71.8 9.8 0.6 — — — — — OOO, OOP
2 1.4 0.7 — 82.9 14.0 0.8 — — — — — OLO
3 16.9 0.8 4.2 73.9 5.1 1.3 — — — — —
Soybean 1 13.8 — 5.9 22.9 48.4 9.1 — — — — — LLL, LLO
2 0.9 — 0.3 21.5 69.7 7.1 — — — — — LLP
3 13.1 — 5.6 28.0 45.2 8.4 — — — — —
Rapeseed 1 4.1 0.3 2.2 23.1 11.1 6.4 — 16.4 1.4 34.9 —
2 0.6 0.2 — 37.3 36.1 20.3 — 2.0 — 3.6 —
3 4.3 0.3 3.0 16.6 4.0 2.6 — 17.3 1.2 51.0 —
Corn 1 17.9 0.3 3.2 27.5 49.8 1.2 — — — — — LLL, LOL
2 2.3 0.1 0.2 26.5 70.3 0.7 — — — — — LLP
3 13.5 0.1 2.8 30.6 51.6 1.0 — — — — —
Peanut 1 13.6 0.3 4.6 59.2 18.5 — 0.7 1.1 c 1.3 — 0.7 OOL, POL
2 1.6 0.1 0.3 58.5 38.6 — — 0.3 c 0.2 — 0.5 OLL
3 11.0 0.3 5.1 57.3 10.0 — 4.0 2.7 c 5.7 — 2.8
Cocoa butter 1 34.0 0.6 50.4 12.3 1.3 — 1.0 — — — — POS, SOS
2 1.7 0.2 2.1 87.4 8.6 — — — — — — SPO
3 36.5 0.3 52.8 8.6 0.4 — 2.3 — — — —
Linseed 1 10.1 0.2 5.6 15.3 15.6 53.2 — — — — —
2 1.6 0.1 0.7 16.3 21.3 59.8 — — — — —
3 6.0 0.3 4.0 17.0 13.2 59.4 — — — — —
Source: refs. 4–11.
a. L denotes 18:2, O 18:1, P 16:0, and S 18:0.
b. Major triacylglycerols are the same for virgin palm oil; approximately 5% diacylglycerols are also present.
c. Together with 18:3 n-3.