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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 16 Proportion of soild fat of native butterfat (�), r<strong>and</strong>omized butterfat (●), <strong>and</strong><br />

butterfat subjected to direct interesterification (▫) measured by dilatometry. (Adapted from<br />

Ref. 90.)<br />

tistically significant effects (p < .05), with catalyst concentration (at 1–2%) having<br />

the greatest influence on hardness, which diminished 45–55%. DeMan [93] observed<br />

by means of polarized light microscopy that the crystal habit of interesterified milk<br />

fat was markedly changed from that of native milk fat. The effects of cooling procedures<br />

on consistency, crystal structure, <strong>and</strong> solid fat content of milk fat were also<br />

examined [94]. Parodi [95] examined the relationship between trisaturates <strong>and</strong> the<br />

softening point of milk fat. Interesterification increased the softening point from<br />

�32.5�C to�36.5�C. Timms [68] found that milk fat <strong>and</strong> beef tallow interesterified<br />

blends lacked milk fat flavor. Timms <strong>and</strong> Parekh [96] explored the possibility of<br />

incorporating milk fat into chocolate. Interesterified milk fat appeared to be better<br />

suited to chocolate than noninteresterified milk fat, but the improvement gained did<br />

not compensate for the investment <strong>and</strong> loss of flavor from interesterification.<br />

E. Fat Substitutes<br />

Newer applications of chemical interesterification include the production of lowcalorie<br />

fat substitutes such as Salatrim <strong>and</strong> Olestra. Salatrim/Benefat consists of<br />

chemically interesterified mixtures of short chain <strong>and</strong> long chain fatty acid triacylglycerols.<br />

The short chain fraction consists of triacetin, tripropionin, <strong>and</strong>/or tributyrin,<br />

while the long chain fractions consist of hydrogenated soybean oil [26].<br />

Olestra is an acylated sucrose polyester with six to eight fatty acids obtained<br />

from vegetable oil (e.g., soybean, corn, sunflower). It is prepared by interesterifying<br />

sucrose <strong>and</strong> edible oil methyl esters in the presence of an alkali catalyst, at 100–<br />

140�C [97]. Olestra is nondigestible, hence noncaloric; it is also nontoxic, yet nutritional<br />

concerns potentially exist. Its functionality is dependent on the chain length<br />

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

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