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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 2 Structure of a physical mixture of medium chain triacylglycerol <strong>and</strong> long chain<br />

triacylglycerol, <strong>and</strong> structured lipid molecular species: M, medium chain fatty acid; L, long<br />

chain fatty acid. Note that physical mixture is not equivalent to structured lipid.<br />

by Procter & Gamble Company (Cincinnati, OH) consists of C8:0-C10:0-C22:0; it<br />

has the physical properties of cocoa butter but only about half the calories. Benefat�,<br />

originally produced as Salatrim (see Sec. II.B.2), consists of short chain (C2:0-<br />

C4:0) <strong>and</strong> long chain (C18:0) fatty acids. Both products can be used as cocoa butter<br />

substitutes. Currently, they are manufactured through a chemical transesterification<br />

process. Because of the low caloric value of the SCFAs <strong>and</strong> the partial absorption<br />

of stearic acid on Salatrim, this product has strong potential for use as a low-calorie<br />

fat substitute in the future. The caloric content of Caprenin <strong>and</strong> Benefat is about 5<br />

kcal/g (vs. 9 kcal/g for a regular TAG). These SLs can also be manipulated for<br />

nutritive <strong>and</strong> therapeutic purposes, targeting specific diseases <strong>and</strong> metabolic conditions<br />

(4). In the construction of SLs for nutritive <strong>and</strong> therapeutic use, it is important<br />

that the function <strong>and</strong> metabolism of various fatty acids be considered. This chapter<br />

focuses mainly on SLs <strong>and</strong> MCTs, emphasizing the use of enzymes for SL synthesis<br />

as an alternative to chemical processing.<br />

II. PRODUCTION OF STRUCTURED LIPIDS<br />

A. Sources of Fatty Acids for Structured Lipid Synthesis<br />

Structured lipids have been developed to optimize the benefit of fat substrate<br />

mixtures (5). A variety of fatty acids are used in the synthesis of SLs, taking advantage<br />

of the functions <strong>and</strong> properties of each to obtain maximum benefits from a given<br />

SL. These fatty acids include short chain fatty acids, medium chain fatty acids,<br />

polyunsaturated fatty acids, saturated long chain fatty acids, <strong>and</strong> monounsaturated<br />

fatty acids. Table 1 gives the suggested levels of some of these fatty acids in SLs<br />

intended for clinical applications. The component fatty acids <strong>and</strong> their position in<br />

the TAG molecule determine the functional <strong>and</strong> physical properties, the metabolic<br />

fate, <strong>and</strong> the health benefits of the SL. It is therefore appropriate to review the<br />

function <strong>and</strong> metabolism of the component fatty acids.<br />

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

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