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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Table 4 Methods to Measure Decomposition Products in Frying Oil<br />

Nonvolatile compounds <strong>and</strong> related processes Method ref.<br />

Iodine value AOCS Cd 1-25/93 (30); AOAC 28.023 (31)<br />

Fatty acid composition AOCS Ce 1-6293 (30)<br />

Total polar compounds AOCS Cd 20-91 (30)<br />

High-performance size exclusion chromatography (36)<br />

Free fatty acids AOCS Ca 5a-40/93 (30)<br />

Dielectric constant (1)<br />

Non-urea-adduct-forming esters (26)<br />

Color AOCS Td 3a-64/93 (30)<br />

Viscosity (32)<br />

Smoke point AOCS Cc 9a-48/93 (30)<br />

Foam height (32)<br />

Volatile compounds <strong>and</strong> related processes<br />

Peroxide value AOCS Cd 8-53 (30)<br />

Conjugated dienes AOCS Ti 1a-64 (30)<br />

Volatile compounds AOCS Cg 4-94 (30)<br />

Sensory analysis of odor <strong>and</strong> flavor (48)<br />

2. Volatile Compounds<br />

The fatty acid composition of frying oils has a major effect on the volatile compounds<br />

detected in the oil <strong>and</strong> on the flavor of the fried food. Although frying oils<br />

are complex mixtures of triacylglycerols, a wide variety of fatty acids, <strong>and</strong> many<br />

minor constituents, degradation compounds are primarily from the fatty acids [5].<br />

Chang et al. [22] found that 79 of 93 compounds identified in corn oil <strong>and</strong> 64 of<br />

Figure 6 Changes in amounts of volatile <strong>and</strong> nonvolatile decomposition products during<br />

the frying process.<br />

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

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