10 Enrichment of Lipids with EPA and DHA
by Lipase
Gudmundur G. Haraldsson
10.1 Introduction
The long-chain n-3 type polyunsaturated fatty acids (PUFA) are characteristic of
marine fat (Ackman, 1989) and commonly occur in triacylglycerols (TG) (Ho ̈l-
mer, 1989) and phospholipids (PL) (Vaskovsky, 1989) of fish. They originate in
the lipids of photosynthetic microalgae that constitute phytoplankton and accumu-
late through the food chain in fish, which are unable to biosynthesize them (Sargent
et al., 1995). Microalgae of marine origin is another important source of n-3 PUFA
which is being utilized to an increasing extent (Henderson, 1999). The most ubiqui-
tous of the n-3 fatty acids in fish arecis-5,8,11,14,17-eicosapentaenoic acid (EPA)
andcis-4,7,10,13,16,19-docosahexaenoic acid (DHA). Fish oil is virtually pure TG
comprising more than 50 different fatty acids (Ackman, 1982). The chain length
ranges from C 14 to C 24 of varying degree of unsaturation, from saturated to poly-
unsaturated. Of the polyunsaturated fatty acids EPA and DHA usually account
for between 5 % and 15 % each, depending on type of fish species, with the total
n-3 content usually varying between 15 % and 25 %. Usually in fish the mid-position
of the glycerol moiety is more enriched with n-3 PUFA, DHA in particular. Fish PL
are generally much more highly enriched with EPA and especially DHA, 20 % to
50 % of each depending on the PL type. The total PL content of fish usually remains
between 1 % and 1.5 % as based on total fish wet weight, roughly an order of mag-
nitude lower than the TG (Haraldsson et al., 1993a).
The beneficial health effects of marine fat are now well established and almost
exclusively attributed to the n-3 PUFA, EPA and DHA in particular (Stansby, 1990;
Nettleton, 1995). There was a boost in the 1980s when it became evident that the n-3
PUFA might offer beneficial effects on the heart and cardiovascular diseases. This
was initiated by reports from Danish scientists based on epidemiological studies on
the Greenland Eskimos with a special emphasis on EPA. During the 1980s, scientists
dedicated their interest almost exclusively to the beneficial effects of EPA on heart
diseases and various inflammatory diseases. Consequently, concentrates aiming at as
high EPA content as possible were under a high demand by the pharmaceutical in-
dustry as well as the health food industry as food supplements, with less emphasis on
DHA. This was soon to change, and recently, there has been a dramatic shift in
interest among scientists toward DHA, and concentrates of high DHA content
are now under even a stronger demand. During the 1990s, it became DHA and
its beneficial effects on pregnancy, infants and brain and nervous system develop-
ment that occupied the attention of scientists (Jumpsen and Clandinin, 1995; Hau-
mann, 1997).
Enzymes in Lipid Modification.Edited by Uwe T. Bornscheuer
Copyright2000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. ISBN: 3-527-30176-3
