Food Lipids: Chemistry, Nutrition, and Biotechnology

lesterol paralleled the decrease in concentration of trisaturates and the scattering of
myristic acid away from sn-2 to sn-1 and sn-3 positions.
Finally, Koga et al. [116] examined the effects of randomization of partially
hydrogenated corn oil on fatty acid and cholesterol absorption and on tissue lipid
levels in rats. They found that interesterification did not lead to beneficial effects but
rather enhanced the hypercholesterolemic tendency of trans fatty acids.
There appears to be some dispute as to the health effects of interesterification.
Whereas the dietary concerns for avoiding trans fatty acids seem well documented,
the nutritional effects of fatty acid positional distribution are presently less clear-cut.
XIII. DISTINGUISHING CHEMICAL FROM ENZYMATIC
INTERESTERIFICATION
Although great strides have been made with extracellular microbial lipases as catalysts
for interesterification, most of the industry still relies on chemical interesterification.
Each type of interesterification possesses advantages and disadvantages. Advantages
of chemical interesterification over enzymatic transformations primarily
involve cost recovery and initial investment. Chemical catalysts are much cheaper
than lipases. Even with immobilization procedures, capital investment remains high.
Second, chemical interesterification is a tried-and-true approach; it has been around
for a long time, and industrial procedures and equipment are available [45].
Costs aside, does treatment by means of chemical or enzymatic interesterification
in identical applications result in the same final product? Kalo et al. [117]
compared the changes in triacylglycerol composition and physical properties of butterfat
interesterified using either sodium methoxide or a nonspecific lipase from Candida
cylindracae and found only small differences in both interesterified butterfats.
The compositional changes induced by both chemical and enzymatic means were
similar, with the trisaturate triacylglycerol content being slightly higher in the enzymatically
modified product. In terms of physical properties, the chemically interesterified
butterfat was slightly harder than its enzymatically modified counterpart.
Hence, for randomization purposes, the methods appeared to yield similar results for
the modification of butterfat. However, the product’s butter flavor must be taken into
account. The harsh process conditions of chemical interesterification result in loss of
butter’s fine flavor. For purposes where flavor is not a problem, the simpler, triedand-true
chemical process is preferable.
Enzymatic interesterification has many advantages, such as milder processing
conditions and the possibility of regiospecificity and fatty acid specificity. This specificity
permits structuring not possible by chemical means. For the production of
nutritionally superior fats, enzymatic interesterification is ideally suited.
XIV. PERSPECTIVES
Chemical interesterification is likely to remain a force in the food industry for the
foreseeable future. With the progressive demise of hydrogenation likely to continue,
interesterification (both chemical and enzymatic) will gain greater prominence as a
food lipid modification strategy.
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.