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Food Lipids: Chemistry, Nutrition, and Biotechnology

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operations, <strong>and</strong> in theory, can replace fats <strong>and</strong> oils on a 1:1 weight basis in foods.<br />

In the literature, the term ‘‘fat substitutes’’ has been used interchangeably with ‘‘fat<br />

replacers,’’ but not with ‘‘fat mimetics,’’ <strong>and</strong> this can be confusing. Several lipidbased<br />

synthetic low-calorie or zero-calorie fat substitutes belong to the fat substitute<br />

group. A good example is sucrose fatty acid polyester (SPE), which was originally<br />

developed as olestra <strong>and</strong> marketed as Olean by Procter & Gamble to replace edible<br />

fats <strong>and</strong> oils in the diet (7). A number of other fat substitutes have been developed<br />

or are under development (8–18). Among these, the carbohydrate <strong>and</strong> alkyl glycoside<br />

fatty acid polyesters <strong>and</strong> the structured lipids (SLs) have functional <strong>and</strong> physical<br />

properties resembling those of triacylglycerols while contributing few to no calories<br />

to the diet (10–20).<br />

Some of the lipid-based fat substitutes can be added to food products to replace<br />

the functional properties of fats, including frying (not possible with protein-based fat<br />

replacers such as Simplesse�, <strong>and</strong> carbohydrate-based fat replacers such as maltodextrin),<br />

while reducing caloric contributions from fats <strong>and</strong> oils. Table 2 lists the<br />

applications <strong>and</strong> functions of some fat replacers. Because the ‘‘ideal’’ fat substitute<br />

does not exist, a systems approach to reduced-fat or low-fat food formulations has<br />

been proposed. Each type of food product will require a different approach to address<br />

the difficulties of formulating a counterpart that has reduced, no, or low fat. Simply<br />

put, a systems approach uses a combination of different ingredients that may or may<br />

not belong to either of the classes of fat replacers <strong>and</strong> requires a basic knowledge<br />

of ingredient technology to formulate desired products. The system may contain<br />

emulsifiers, fat substitutes or mimetics, fibers, water control ingredients, flavor, <strong>and</strong><br />

bulking agents. Water or moisture control poses one of the greatest challenges in<br />

formulating reduced-fat snack <strong>and</strong> baked goods. In these systems water is used to<br />

replace fat, to increase bulk, or for functionality. A detailed review of fat mimetics<br />

is outside the scope of this chapter, which concentrates on lipid-based fat substitutes.<br />

III. TYPES OF LIPID-BASED SYNTHETIC FAT SUBSTITUTES<br />

Lipid-based fat substitutes include carbohydrate fatty acid polyesters such as sucrose<br />

polyester, sorbitol polyester, raffinose polyester, stachyose polyester, <strong>and</strong> alkyl glycoside<br />

fatty acid polyesters. Others include Caprenin, Salatrim (short <strong>and</strong> long acyl<br />

triglyceride molecules, marketed as Benefat), structured lipids, medium chain triacylglycerols<br />

(MCTs), mono- <strong>and</strong> diacylglycerols, esterified propoxylated glycerol<br />

(EPG), dialkyl dihexadecylmalonate (DDM), <strong>and</strong> trialkoxytricarballylate (TATCA),<br />

to name a few. The composition <strong>and</strong> sources or developers of the lipid-based fat<br />

substitutes are shown in Table 3.<br />

Of all the lipid-based fat substitutes, only sorbitol, trehalose, raffinose, <strong>and</strong><br />

stachyose polyesters have a chance to compete with Olestra as nondigestible zerocalorie<br />

fat substitutes. Others are either partially hydrolyzed or fully hydrolyzed <strong>and</strong><br />

absorbed, thus contributing some calories to the diet.<br />

A. Strategies for Designing Lipid-Based Fat Substitutes<br />

Several strategies were suggested for designing low-calorie or zero-calorie lipidbased<br />

synthetic fat substitutes (2,16). The basic premise is to reengineer, redesign,<br />

chemically alter, or synthesize conventional fats <strong>and</strong> oils such that they retain the<br />

Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.

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