Front Matter

in the high-erucic rapeseed oil to 66 % in the tri-, di- and monoacylglycerols (Bail-

largeon and Sonnet, 1991). In the esterification of fatty acids of high-erucic rapeseed

oil withn-butanol, catalyzed by lipase fromG. candidum, strong discrimination

against erucic acid has been reported, which leads to enrichment of erucic acid

from 47 % in the fatty acid mixture to 83 % in the unesterified fatty acids (Sonnet

et al., 1993a). Partial hydrolysis of high-erucic rapeseed oil, catalyzed byC. rugosa

lipase yields dierucin in 73 % purity which has been used for lipase-catalyzed synth-

esis of trierucin (Trani et al., 1993).

Selective hydrolysis of triacylglycerols of meadowfoam (Limnanthes alba) oil

containing over 60 %cis-5-eicosenoic acid (cis-5-20 : 1) results in enrichment of

cis-5-20 : 1 in tri- + di- + monoacylglycerols when lipase fromChromobacterium

viscosumis used as biocatalyst (Hayes and Kleiman, 1993). Selective esterification

of meadowfoam oil fatty acids withn-butanol, catalyzed byC. viscosumlipase, leads

to enrichment ofcis-5-20 : 1 in the unesterified fatty acids in excellent yield (>95 %)

and purity (>99 %) (Hayes and Kleiman, 1993).

Partial hydrolysis and transesterification of high-erucic oils catalyzed by several

lipases have been studied with the objective to develop strategies for the enrichment

of VLCMFA utilizing the selectivity of these enzymes (Mukherjee and Kiewitt,

1996a). Lipase-catalyzed selective hydrolysis of high-erucic oils from white mus-

tard (Sinapis alba) and oriental mustard (Brassica juncea), has revealed that the

lipases studied can be broadly classified into three groups according to their sub-

strate selectivity.

The first group includes lipases fromC. cylindraceaandG.candidumthat selec-

tively cleave the C 18 acyl moieties from the triacylglycerols; this results in enrich-

ment of these fatty acids in the fatty acid fraction. Concomitantly, the level of erucic

acid and the other VLCMFA is raised in the mono- + di- + triacylglycerol fraction

from 51 % in the starting oil to about 80 % and 72 %, respectively, when lipases from

C. rugosaandG. candidumare used as biocatalyst (Mukherjee and Kiewitt, 1996a).

The second group includes lipases from porcine pancreas,C. viscosum,R. arrhizus

andR. miehei, with their known regioselectivity towards acyl moieties at thesn-1,3

positions of triacylglycerols (Mukherjee, 1990). With these lipases the VLCMFA,

esterified almost exclusively at thesn-1,3 positions of the triacylglycerols of the

high-erucic oils, are selectively cleaved and the resulting VLCMFA enriched in

the fatty acid fraction to levels as high as 65–75 % (Figure 5); simultaneously

the level of the C18 fatty acids is increased in the acylglycerol fraction (Mukherjee

and Kiewitt, 1996a).

The third group includes lipases fromPenicilliumsp. (Lipase G) andCandida

antarctica(Lipase B), which do not seem to exhibit any pronounced specificity

towards either C 18 fatty acids or VLCMFA (Mukherjee and Kiewitt, 1996a).

The lipases with strong fatty acid selectivity or regioselectivity have been tested

for the selective hydrolysis of the triacylglycerols of honesty (Lunaria annua) seed

oil which is rich in VLCMFA, including nervonic acid. TheC. rugosalipase cleaves

preferentially the C 18 fatty acids, which are enriched from 36 % in the starting oil to

79 % in the fatty acids, while the VLCMFA are enriched in the di- and triacylgly-

cerols. In particular, the diacylglycerols were almost exclusively (>99 %) composed

of VLCMFA, whereas barely traces of monoacylglycerols were formed (Mukherjee

and Kiewitt, 1996a).

36 2 Fractionation of Fatty Acids and Other Lipids Using Lipases