Front Matter

This has resulted in strong demands for their concentrates by the pharmaceutical

industry, as well as the health food industry, as food supplements. In this chapter, the

involvement and use of lipase in the n-3 field will be discussed. First, their applica-

tion will be put in perspective with recent development and demand for various

concentration forms of EPA and DHA and how they have found use in concentrating

EPA and DHA in fish oil. Also, how they can be utilized to prepare structurally

labeled lipids and finally, their role in the synthesis of various lipid forms containing

EPA and DHA. More details are provided in the divided (though by no means ex-

haustive) review sessions, where our own contributions in the field are discussed in

more detail and put into context with other related work.

10.2 Recent developments and role of lipase

in the n-3 field

Concentrates of EPA and DHA first appeared on the market in the early 1980s. Max

EPAwas the first dietary n-3 supplement product on the market containing 18 % EPA

and 12 % DHA in the natural TG form (Seven Seas, 1994). It has been widely used

for various clinical studies for more than 15 years. TG up to the level of 30 %

EPA+DHA can be prepared directly from fish oils without splitting the fat by a

careful selection of fish oils and various methods such as winterization, molecular

distillation and solvent crystallization (Ackman, 1988; Breivik and Dahl, 1992).

Concentration beyond that level on the TG form is difficult, as it requires a cleavage

of the fatty acids off the acylglycerols, either as free acids or monoesters. Various

physical methods and combination of methods are available for concentrating EPA

and DHA once released. Molecular distillation, supercritical fluid extraction and

urea complexation can be used to concentrate them to the 50–85 % level. Concen-

tration beyond the 90 % level and separation and purification of EPA and DHA

requires more specific methods based on HPLC (Breivik et al., 1997). Awhole range

of monoester concentrates of EPA and DHA are now commercially available, usually

as ethyl esters, some of which have been registered as drugs in various countries.

Resynthesis of TG highly enriched with EPA and DHA from the concentrates is by

no means easy by traditional chemical esterification methods based on Lewis acid or

alkoxide catalysis. The highly labile n-3 PUFA are very sensitive against the rather

drastic conditions offered by these traditional methods. The all-cisn-3 framework

makes them extremely prone to oxidation,cis-transisomerization, double-bond mi-

gration, or polymerization. Despite that, some European companies have recently

launched onto the market a whole variety of TG concentrates comprising 50–

70 % EPA+DHA. These products usually constitute a mixture of roughly 55 %

TG, 35–40 % diacylglycerols (DG) and 5–10 % monoacylglycerols (MG), which

apparently reflects some compromise between efficiency and lability in their pro-

duction.

Recently, lipases have been introduced to the n-3 field to solve these problems

(Haraldsson and Hjaltason, 1992). These enzymes offer a high efficiency and mild-

ness, and their application in organic media is now firmly established (Bornscheuer

10.2 Recent developments and role of lipase in the n-3 field 171