Food Lipids: Chemistry, Nutrition, and Biotechnology

influence of interesterification on crystal morphology of binary and ternary mixtures
of trilaurin, triolein, and tristearin. He also found that fat crystals following interesterification
were smaller than before randomization and had different morphologies.
A study of butterfat-canola oil blends revealed that gradual addition of canola oil
led to gradual spherulitic aggregation of the crystal structure [75].
B. Chemical Properties
Changes in physical properties provide an arbitrary measure of interesterification
structural modifications but give no real information on the compositional changes.
Following these changes can be difficult unless simple substances are used [33].
Studies on molecular rearrangement of triacylglylcerol species provide a true indication
of the chemistry of interesterification. The chemistry of interesterification can
be followed with different chromatographic techniques: TLC, HPLC, and GLC.
Freeman [33], who examined the changes in monounsaturated triacylglycerols
during the course of interesterification with TLC, found that intraesterification occurred
at a faster rate than the general randomization that results from interesterification.
Chobanov and Chobanova [57] made extensive use of TLC to study the alteration
in composition of 10 triacylglycerol groups during the monophasic interesterification
of mixtures of sunflower oil with lard and tallow.
Parviainen et al. [81] studied the effects of randomization on milk fat triacylglycerol;
they found an S2U decrease in C36 and C38 species (45% and 52%, respectively)
and an increase in trisaturated C44–C50 species. This combination led
to a broader crystallization range and higher SFCs at temperatures above 25�C.
Herslöf et al. [82] used reversed phase HPLC and GC to analyze the interesterification
reaction between fatty acid methyl esters and trilaurin and found that the
theoretical and experimental compositions for the interesterified systems matched.
Rossell [70] measured the evolution in triacylglycerol species following chemical
interesterification of palm kernel oil by means of GLC.
Huyghebaert et al. [60] and Rousseau et al. [34] used GLC to follow the
evolution of butterfat triacylglycerol species as a result of interesterification. Typical
results are shown in Figure 14.
X. APPLYING INTERESTERIFICATION TO FOOD LIPIDS
Chemical interesterification is used industrially to produce fats and oils used in margarines,
shortenings, and confectionery fats [60]. Due to legislation and for economic
reasons, interesterification is a more common process in Europe than in North America.
It is popular for many reasons. For example, little in the way of chemical properties
is affected, and the fatty acid distribution is changed but the fatty acids’ inherent
properties are not. Moreover, unsaturation levels stay constant and there is no
cis-trans isomerization [36,43]. Interesterification can improve the physical properties
of fats and oils. Similar changes in physical properties may be obtained by means
of blending, fractionation, or hydrogenation. Production costs, market prices, or raw
material and nutritional concerns will determine the process to be used. Applications
described include lard, margarines, palm oil and palm kernel oil, milk fat, and fat
substitutes.
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.