Food Lipids: Chemistry, Nutrition, and Biotechnology

27
Enzymatic Interesterification
WENDY M. WILLIS
Ives’ Veggie Cuisine, Vancouver, British Columbia, Canada
ALEJANDRO G. MARANGONI
University of Guelph, Guelph, Ontario, Canada
I. INTRODUCTION
The development of methods to improve the nutritional and functional properties of
fats and oils is of great interest to food processors. The molecular weight, unsaturation,
and positional distribution of fatty acid residues on the glycerol backbone of
triacylglycerols are the principal factors determining the physical properties of fats
and oils (1,2). Chemical interesterification produces a complete positional randomization
of acyl groups in triacylglycerols. It is used in the manufacture of shortenings,
margarines, and spreads to improve their textural properties, modify melting behavior,
and enhance stability (3,4). Interest in interesterification from a nutritional and
functional standpoint is increasing since it can be used to produce margarines with
no trans unsaturated fatty acids, synthesize cocoa butter substitutes and improve the
nutritional quality of some fats and oils (5). Recently, research efforts have been
directed to substituting some chemical interesterification applications with enzymatic
interesterification because of the inherent advantages associated with the enzymatic
process. Enzymatic reactions are more specific, require less severe reaction conditions,
and produce less waste. Also, when immobilized, enzymes can be reused,
thereby making them economically attractive (6). Interesterification, whether chemical
or enzymatic, is the exchange of acyl groups between an ester and an acid
(acidolysis), an ester and an alcohol (alcoholysis), an ester and an ester (transesterification)
(7).
The major components of fats and oils are triacylglycerols, the composition of
which is specific to the origin of each fat or oil. The physical properties of various
fats and oils are different because of the structure and distribution of fatty acids in
the triacylglycerols (8). In natural fats, acyl groups are distributed in a nonrandom
fashion. During chemical or enzymatic interesterification, acyl groups are redistrib-
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.