Food Lipids: Chemistry, Nutrition, and Biotechnology

Tautorus and McCurdy [102] demonstrated the effects of chemical and enzymatic
randomization on the oxidative stability of vegetable oils stored at different
temperatures. Noninteresterified and interesterified oils (canola, linseed, soybean, and
sunflower) stored at 55�C demonstrated little difference to lipid oxidation, whereas
noninteresterified samples were more stable at 28�C. Samples at 55�C underwent
much greater oxidation than the samples at 28�C.
Park et al. [103] found that loss of tocopherols accelerated the autoxidation of
randomized oils. �-Tocopherol was not detectable following interesterification, while
�-tocopherol and �-tocoperol diminished 12% and 39%, respectively.
Konishi et al. [104] found that regioselectively interesterified blends of methyl
stearate and soybean oil had increased oxidative stability over both native and randomized
blends, as monitored by peroxide value and volatiles analysis. The improved
oxidative stability was presumably due to the regioselective incorporation of stearic
acid at the sn-1(3) carbon sites of the triacylglycerol moiety, which stabilized the
linoleic acid, predominantly located at the sn-2 position.
XII. NUTRITIONAL CONSEQUENCES OF INTERESTERIFICATION
Perhaps chemical interesterification’s greatest advantage over hydrogenation lies in
nutrition. At present, there are still unsettled nutritional concerns regarding trans
fatty acids and their possible links to coronary heart disease [105–107]. Trans fatty
acids are present in many edible fats and oils produced worldwide, yet these substances
occur in great proportions in partially hydrogenated margarines. Barring nonhydrogenated
margarines, literature data indicate that the typical trans fatty acid
content of margarines is 10–27% in the United States and 10–50% in Canada
[108,109].
It has been shown that randomization does not influence the nutritional value
of unsaturated fatty acids [110]. However, not much is known about the potential
importance of stereospecificity in the biological activity of dietary fatty acids [111].
In clinical trials, substitution of randomized butter for natural butter tended to reduce
serum triacylglycerol and cholesterol concentrations [112]. Human infants absorbed
88% stearic acid when fed lard but only 40% when fed randomized lard. Hence,
absorbability and pharmacological properties of fatty acids can be influenced by the
molecular form in which they are absorbed [63].
De Schrijver et al. [111] examined lipid metabolism response in rats fed tallow,
native or randomized fish oil, and native or randomized peanut oil and found that
randomized lard had no significant effects on any of the lipid measurements. Absorption
of oleic acid and polyunsaturated fatty acids did not depend on the fatty
acid profile of dietary fat. Kritchevsky [113] found that peanut oil’s tendency to
produce atherogenicity in rabbits disappeared following chemical interesterification.
It is known that human milk is well absorbed in part because of its proportion
of long chain saturated fatty acids located at the sn-2 position. Lien et al. [114] found
that mixtures of coconut oil and palm olein were better absorbed by rats if the
proportion of long chain saturated fatty acids at the sn-2 position was increased by
random chemical interesterification.
Mukherjee and Sengupta [115] found that interesterified soya–butterfat feeding
significantly decreased serum cholesterol in humans and rats. The decrease was
greater than when noninteresterified blends were fed. The lowering of serum cho-
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