Food Lipids: Chemistry, Nutrition, and Biotechnology

Figure 1 Structure of sucrose polyester (Olean).
granted the original patent for sucrose polyester in 1971, spent over $250 million
over the last 25 years to develop this fat substitute. The original application for use
of sucrose polyester as a food additive, filed with the Food and Drug Administration
(FDA) in April 1987, was withdrawn and modified. But on January 24, 1996, the
FDA approved olestra for limited use in savory snacks (namely, chips, curls, and
crackers). Before the approval, sucrose polyester was evaluated in over 10 animal
studies and in 25–30 clinical trials. The approval of olestra was not without controversy.
The Center for Science in the Public Interest (CSPI), a Washington consumer
advocate group, believes that olestra deprives the body of some of the essential
vitamins and carotenoid that may protect against cancer. In 1996, in Iowa, Wisconsin,
and Colorado, Frito-Lay, a unit of PepsiCo, test-marketed chips made with the
olestra.
1. Synthetic Approaches
Sucrose fatty acid polyester can be synthesized in the presence or absence of organic
solvent. Direct esterification of sucrose with fatty acid is very difficult. The solventfree
process is widely used for the current production of sucrose polyester (18,22).
The synthesis may involve reactions of the following types:
1. Transesterification. Fatty acid methyl esters (FAMEs) and sucrose are reacted
in the presence of potassium soaps to form a homogeneous melt
followed by the addition of excess FAME and NaH at 130–150�C. In some
cases, potassium carbonate is added to aid the reaction. The function of
soap is to help solubilize sucrose and FAME. Methanol, a by-product of
the transesterification reaction, is distilled off (Fig. 2). The active catalyst
is the sucrate ion generated with alkali metal hydrides. This is a two-stage
transesterification process, and up to 8–9 hours may be needed to achieve
90% yield of SPE.
2. Interesterification (ester interchange). This involves reacting a short chain
alkyl ester such as sucrose octaacetate (SOAc) with FAME in the presence
of sodium methoxide (NaOCH 3) or Na or K metal as catalyst (14). The
reaction requires extremely anhydrous conditions to prevent hydrolysis of
formed product, catalyst inactivation, or explosion (when Na is in contact
with water). The temperature of the reaction with Na catalyst is lower
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.