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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 13 The effects of 0, 2, 4, 6, <strong>and</strong> 8 ppm chlorophyll on the formation of head space<br />

volatile compounds of soybean oil under light [44].<br />

ganoleptic evaluation of the addition of 2 ppm 2-pentylfuran to freshly deodorized<br />

<strong>and</strong> bl<strong>and</strong> soybean oil was found to provide the ‘‘reverted’’ soybean oil flavor. The<br />

addition of 2 ppm 2-pentylfuran to deodorized cottonseed oil <strong>and</strong> corn oil produced<br />

reversion flavor found in reverted soybean oil [48].<br />

Ho <strong>and</strong> others [46] determined that 2-(1-pentenyl)furan contributed to reversion<br />

flavor. In a similar study, Smagula <strong>and</strong> others [49] reported that 2-(2-pentenyl)furan<br />

is also a contributor according to detailed organoleptic evaluation. Flavor thresholds<br />

of the 2-pentenylfuran isomers were found to be between 0.25 <strong>and</strong> 6 ppm. Chang<br />

<strong>and</strong> others [50] isolated <strong>and</strong> identified all four 2-pentenylfuran isomers in reverted<br />

soybean oil.<br />

Mechanisms for the formation of 2-pentylfuran from linoleic acid <strong>and</strong> 2-pentenylfuran<br />

isomers from linolenic acid using triplet oxygen were proposed by Chang<br />

<strong>and</strong> others [48] <strong>and</strong> Ho <strong>and</strong> others [46], respectively. Formation of both 2-pentylfuran<br />

<strong>and</strong> 2-pentenylfuran requires a hydroperoxide intermediate at carbon 10. Formation<br />

of 10-hydroperoxide in linoleic or linolenic acids by free radical triplet oxygen oxidation<br />

is highly improbable, but is very common in the singlet oxygen oxidation of<br />

linoleic or linolenic acids as shown in Table 2. Min [51] reported that the chemical<br />

mechanisms for the formations of 2-pentylfuran from linoleic acid <strong>and</strong> 2-(2-pentenyl)furan<br />

formation from linolenic acid using singlet oxygen as shown in Figures<br />

14 <strong>and</strong> 15, respectively.<br />

Callison [52] identified 2-pentylfuran <strong>and</strong> 2-pentenylfuran in soybean oil containing<br />

5 ppm chlorophyll b during storage under light for 96 hours, as shown in<br />

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

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