Food Lipids: Chemistry, Nutrition, and Biotechnology

B. Margarines
In the manufacture of margarine, the object is to produce a fat mixture with a steep
solid fat content curve to obtain a stiff product in the refrigerator that nevertheless
spreads easily upon removal and melts quickly in the mouth. It should crystallize as
a �� polymorph [87]. Depending on oil costs and availability, different treatments
can be used.
As an alternative to hydrogenation for the production of margarine, Lo and
Handel [61] chemically interesterified blends of 60% soybean oil with 40% beef
tallow. Final results indicated properties similar to those of commercial tub margarine
oil. Yet the interesterified blend contained less polyunsaturated fatty acids and more
saturated fatty acids than commercial margarine oil.
According to Sonntag [31], short and medium chain fatty acids (C6–C14) have
good melting properties whereas long chain fatty acids (C20–C22) can provide stiffening
power in margarine. Acids of these two types can be combined with interesterification
to produce triacylglycerols that provide blends with good spreadability,
high temperature stability, and a pleasant taste.
Margarine oil with high proportions of lauric acid has a low melting point and
narrow plastic range, which leads to a margarine that is hard in the fridge but partly
melts at room temperature [87]. Decreasing the lauric acid concentration can rectify
this problem of extremes. For example, coconut oil can be interesterified with an oil
such as palm, and 60% of the interesterified mixture then blended with 40% oil,
such as sunflower oil.
In the manufacture of zero-trans margarines, chemical interesterification of soybean
oil-soy trisaturate using 0.2% (w/w) sodium methoxide at 75–80�C for 30
minutes resulted in a ��-crystallizing fat with good organoleptic properties [64].
List et al. [77] described the preparation of potential margarine and shortening
bases by interesterification of vegetable oil and hardstocks (hydrogenated oil or stearin).
They found that the interesterified fats possessed plasticity curves similar to
those of commercial soft-tub margarine oils prepared by blending hydrogenated
hardstocks or commercial all-purpose shortening oils. However, the commercial
blends and interesterified blends differed with respect to crystallization behavior.
C. Palm Oil and Palm Kernel Oil
Palm oil has many applications in the food industry. Most often, interesterification
of palm oil is combined with hydrogenation and/or fractionation to achieve the most
desirable physical and functional properties [14]. Laning [14] described the applications
of palm oil in cooking, frying, and salad oils. Corandomization of palm oil
with other fats and oils, in combination with fractionation, produced a fluid salad
oil.
Cocoa butter, used in the production of chocolate, is expensive and not always
available, so substitutes are created, such as those that result from the blending of
interesterified lauric acid with other fats. According to Sreenivasan [1], palm kernel
oil is a hard butter that melts at 46�C and produces a waxy feel. With interesterification,
the melting point is reduced to 35�C. Furthermore, by blending hydrogenated
PKO and the randomized product, a whole series of hard butters with highly desirable
melting properties is obtained. The effect of randomization on the melting properties
of cocoa butter is shown in Figure 15.
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