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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 5 Structure of sorbitol polyester.<br />

Recently, Chung et al. (33) optimized the synthesis of sorbitol fatty acid polyesters.<br />

Procter & Gamble also worked on sorbitol polyesters but did not follow up<br />

on their development. The properties <strong>and</strong> applications in food have not been extensively<br />

studied as with olestra. However, sorbitol polyesters are proposed as zerocalorie<br />

fat substitutes. They are less viscous than sucrose polyester <strong>and</strong> slightly more<br />

viscous than vegetable oils (13). Based on the known structure <strong>and</strong> limited metabolic<br />

studies, sorbitol polyesters may be used in place of olestra in food products. They<br />

are stable to high heat <strong>and</strong> taste <strong>and</strong> function like fats.<br />

2. Sorbestrin<br />

Sorbestrin is sorbitol or cyclic sorbitol containing three to five fatty acids esterified<br />

to the OH group. It was developed by Pfizer Inc. Sorbestrin contains 1.5 kcal/g <strong>and</strong><br />

has a bl<strong>and</strong> oil-like taste with cloud point between 15�C <strong>and</strong> 13�C. It is mainly a<br />

clear liquid <strong>and</strong> can serve as a reduced-calorie fat substitute. It is thermally stable<br />

<strong>and</strong> can withst<strong>and</strong> frying temperatures. It is intended for use in frying, baking, <strong>and</strong><br />

salad dressings. Sorbestrin is not yet commercially available <strong>and</strong> will require food<br />

additive petition <strong>and</strong> FDA approval prior to use. Akoh <strong>and</strong> Swanson (13) synthesized<br />

sorbitol hexaoleate as a low-calorie fat substitute. Pfizer noted that for humans, sorbestrin<br />

consumption in the future is estimated at 12 g/day. The structure of sorbestrin<br />

is shown in Figure 6.<br />

3. Trehalose Polyester<br />

Trehalose is a nonreducing disaccharide, the major sugar of insect hemolymph, fungi,<br />

<strong>and</strong> yeasts. It is made of two �-D-glucopyranose components <strong>and</strong> closely resembles<br />

sucrose in physical properties. The nonreducing sugars are better substrates for the<br />

synthesis of fat substitutes than the reducing sugars. This is because the anomeric<br />

carbon atoms (C-1) of nonreducing sugars are protected <strong>and</strong> not very susceptible to<br />

thermal degradation. The reducing sugars degrade <strong>and</strong> caramelize at the high temperatures<br />

required for transesterification. The use of acetyl derivatives of nonreducing<br />

sugars allows reactions to be carried out at reduced temperatures (

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