Front Matter

isolated by evaporation and converted to triacylglycerols via hydrolysis and reester-

ification, both catalyzed byR. mieheilipase (Moore and McNeill, 1996).

UsingR. delemarlipase, selective esterification with lauryl alcohol of fatty acids

from tuna oil has yielded an unesterified fatty acid fraction containing 73 % n-3 22 : 6

as compared to 23 % in the starting material (Shimada et al., 1997e). Using the same

lipase, selective esterification of tuna oil fatty acids with lauryl alcohol, extraction of

the unreacted fatty acids and their repeated esterification with lauryl alcohol has

resulted in an unesterified fatty acid fraction containing as much as 91 % n-3

22 : 6 (Shimada et al., 1997a).

Interesterification (acidolysis) of marine oil triacylglycerols with marine oil fatty

acid fractions, that have been enriched with n-3 polyunsaturated fatty acids, has been

carried out using lipase fromPseudomonassp. to raise the level of total n-3 poly-

unsaturated fatty acids in the triacylglycerols to 65 % (Adachi et al., 1993).

Moreover, lipase-catalyzed selective alcoholysis of marine oil triacylglycerols or

alkyl esters of marine oil fatty acids with short- or long-chain alcohols has resulted in

the enrichment of n-3 polyunsaturated fatty acids in the acylglycerol fraction or alkyl

ester fraction, respectively. Thus, selective alcoholysis of ethyl esters of tuna oil fatty

acids with ethanol usingR. delemarlipase andR. mieheilipase as biocatalyst leads to

enrichment of n-3 22 : 6 in the ethyl ester fraction from 23 mol% to about 50 mol%

(Shimada et al., 1997d) and from 60 mol% to 93 mol% (Shimada et al., 1998c).

However, withR. mieheilipase as biocatalyst selective interesterification of tuna

oil triacylglycerols with ethanol yields an acylglycerol fraction containing 49 %

n-3 22 : 6, whereas selective esterification of tuna oil fatty acids with ethanol yields

an unesterified fatty acid fraction containing 74 % n-3 22 : 6 (Haraldsson and Kris-

tinsson, 1998).

2.2.4 Enrichment of very long-chain monounsaturated fatty acids

(VLCMFA)

Very long-chain monounsaturated fatty acids (VLCMFA), such as gondoic (cis-11-

eicosenoic, 20 : 1) acid, erucic (cis-13-docosenoic, 22 : 1) acid (Mikolajczak et al.,

1961; Knowles et al., 1981), nervonic (cis-15-tetracosenoic, 24 : 1) acid (Mukherjee

and Kiewitt, 1986) andcis-5-eicosenoic acid (Joliff, 1981) are abundant constituents

of seed oils, especially from Cruciferae. Erucic acid and its derivatives are exten-

sively used for the manufacture of a wide variety of oleochemical and technical

products (Sonntag, 1991), and other VLCMFA might also find novel applications

in hitherto less explored areas.

Erucic acid is currently isolated from high-erucic oils by fat splitting followed by

fractional distillation, both of which are rather energy-consuming processes. Lipase-

catalyzed selective hydrolysis of high-erucic triacylglycerols has been proposed as

alternative process for the isolation of erucic acid (Baillargeon and Sonnet, 1991;

Ergan et al., 1992; Kaimal et al., 1993). Hydrolysis of high-erucic oils, catalyzed

by lipases fromG. candidum(Baillargeon and Sonnet, 1991) andC. rugosa(Ergan

et al., 1992; Kaimal et al., 1993) leads to enrichment of erucic acid in the tri-, di- and

monoacylglycerols (see Figure 4). Thus, the level of erucic acid is raised from 43 %

2.2 Fractionation of fatty acids and other lipids by lipase-catalyzed reactions 35