Food Lipids: Chemistry, Nutrition, and Biotechnology

Figure 20 Preparation of structured triacylglycerols of the monoglyceride diacetate and
diglyceride monoacetate types by lipase-catalyzed transesterification.
alba, Lunaria annua (138), or Crambe abyssinica (139), which contain large proportions
of very long chain monounsaturated fatty acids esterified at the sn-1 and
sn-3 positions, with very long chain alcohols derived from these oils, as shown in
Fig. 23. Similarly, long chain wax esters resembling jojoba oil were obtained in high
yields when fatty acids obtained from seed oils of crambe (Crambe abyssinica) and
camelina (Camelina sativa) were esterified with oleyl alcohol or the alcohols derived
from crambe and camelina oils using Novozym 435 (immobilized lipase B from
Candida antarctica) or papaya (Carica papaya) latex lipase as biocatalysts and vacuum
was applied to remove the water formed (140). Further examples of lipasecatalyzed
preparation of wax esters via esterification (141–146) and interesterification
(143–145,147–150) are known.
Unusual wax esters have also been obtained in good yields by lipase-catalyzed
reactions, such as esterification of decanol with fatty acids, e.g., 9(10)hydroxymethyloctadec-10-enoic
acid and transesterification of octanol with methyl esters of 9,10epoxy-
or 9-oxodecanoic acids (151).
Lipozyme has been shown to catalyze the esterification of a great variety of
carboxylic acids, including short chain, long chain, and branched chain acids to
different types of alcohols, ranging from short chain and long chain alkanols to cyclic
alcohols (152) giving almost theoretical yields if the water formed by esterification
is efficiently removed (105,152).
Esterification catalyzed by immobilized lipases from Rhizomucor miehei
(105,152,153) and Candida rugosa (154) as well as surfactant-coated microbial lipases
(155) have been carried out for the preparation of a wide variety of alkyl esters
of fatty acids in high yields. Moreover, lipase-catalyzed transesterification (alcoholysis)
of triacylglycerols with an alcohol, such as n-butanol (156), ethanol or isopropanol
(157) provide alkyl esters in high yields, whereby the use of silica gel as
an adsorbent for glycerol formed by the reaction greatly enhances the yield (156).
Transesterification (alcoholysis) of low-erucic rapeseed oil with 2-ethyl-1-hexanol,
catalyzed by lipase from Candida rugosa, provides 2-ethyl-1-hexyl esters of
rapeseed fatty acids in high yields that can serve as a solvent for printing ink (158).
Figure 21 Lipase-catalyzed synthesis of bioesters.
Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.