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Food Lipids: Chemistry, Nutrition, and Biotechnology

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lipoxygenase has been used for example to prepare 9-hydroperoxy-�-linolenic acid<br />

from �-linolenic acid (329), hydroperoxides of acylglycerols <strong>and</strong> phospholipids<br />

(330,331) <strong>and</strong> dimers of linoleic acid (332).<br />

Recently, lipoxygenase immobilized in a packed-bed column reactor has been<br />

used to convert linoleic acid to hydroperoxyoctadecadienoic acid (333). Furthermore,<br />

a double-fed batch reactor fed with a mixture of linoleic acid together with a crude<br />

lipoxygenase extract from defatted soybean flour has been used to obtain hydroperoxyoctadecadienoic<br />

acid, which is subsequently reduced in situ by cysteine, also<br />

contained in the reactor, to give 13(S)-hydroxy-9-cis,12-cis-octadecadienoic acid in<br />

high yield (334).<br />

2. Oxygenases<br />

Crude enzyme preparations from a variety of organisms have been shown to exhibit<br />

interesting activities that can be utilized for the biotransformation of fats <strong>and</strong> other<br />

lipids. For example, enzyme preparation from plants have been shown to catalyze<br />

�-hydroxylation (Fig. 46) (335) <strong>and</strong> epoxidation (Fig. 47) (336) of fatty acids. Recently,<br />

a peroxygenase isolated from oat (Avena sativa) has been immobilized on<br />

synthetic membranes <strong>and</strong> employed for the epoxidation of oleic acid using hydrogen<br />

peroxide or organic hydroperoxides as oxidants (337).<br />

Enzyme preparations containing alcohol oxidase, isolated from the yeast C<strong>and</strong>ida<br />

tropicalis, catalyze the oxidation of long chain alcohols, diols, <strong>and</strong> �-hydroxy<br />

fatty acids to the corresponding aldehydes (Fig. 48) (338). Alcohol oxidase preparations,<br />

isolated from the yeast C<strong>and</strong>ida maltosa, catalyze the oxidation of 1-alkanols<br />

<strong>and</strong> 2-alkanols to the corresponding aldehydes <strong>and</strong> ketones, respectively (339).<br />

3. Epoxide Hydrolases<br />

Expoxide hydrolases (EC 3.3.2.3) are ubiquitous in nature (340). They catalyze the<br />

hydrolysis of epoxides to vicinal diols. In particular, epoxide hydrolases from higher<br />

plants are well characterized (341–345).<br />

Epoxide hydrolase from soybean seedlings catalyzes the hydration of cis-9,10epoxystearic<br />

acid to threo-9,10-dihydroxystearic acid (Fig. 49) (341):<br />

The two positional isomers of linoleic acid monoepoxides are hydrated to their<br />

corresponding vic-diols by soybean fatty acid epoxide hydrolase (Fig. 50) (342).<br />

The epoxide hydrolase has been found to be highly enantioselective with strong<br />

preference for the enantiomers cis-9R,10S-epoxy-cis-12-octadecenoic acid <strong>and</strong> cis-<br />

12R-,13S-epoxy-cis-9-octadecenoic acid, respectively (342–344).<br />

Strong enantioselection has also been reported for rabbit liver microsomal<br />

epoxide hydrolase (346). Cloning <strong>and</strong> expression of soluble epoxide hydrolase from<br />

potato (347) <strong>and</strong> purification as well as immobilization of epoxide hydrolase from<br />

rat liver (348) have been reported. Commercial availability of such enzyme preparations<br />

is a prerequisite for their application in biotransformation of fats for the<br />

preparation of products via hydration of epoxides, e.g., hydroxylated fatty acids<br />

(349).<br />

IV. USE OF ENZYMES IN TECHNOLOGY OF OILSEEDS, OILS,<br />

AND FATS<br />

Enzymes are gaining importance as processing aids in the technology of oilseeds,<br />

oils, <strong>and</strong> fats. Use of enzymes to facilitate the recovery of oils from oilseeds <strong>and</strong><br />

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

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