3.2. Fatty acid composition
A total number of 33 fatty acids of various chain lengths and
saturation levels were identified by gas–liquid chromatography
(Table 2). Of the saturated fatty acids (SFA) palmitic acid (C16:0)
and stearic acid (C18:0) were found to be the dominant ones in all
species sampled. These fatty acids occur naturally in fish and
shellfish lipids, as in all animal fats, and are the major products of
the fatty acid synthetase system (Sargent et al., 2002). C16:0 and
C18:0, as well as C18:1n-9, are also the major sources of metabolic
energy in fish for growth (Sargent et al., 2002). All other SFA were
minor components though C14:0 and C15:0 comprised 1.3–2.2% in
R. borapetensis, P. brevis and M. nipponense (Table 2). R. borapetensis
had significantly higher SFA than all the other species. The higher
SFA levels in R. borapetensis were attributed mainly to the higher
levels of C16:0 but also of C14:0 and C15:0 in these fish (Table 2). It
has been suggested that levels of SFA are regulated within a narrow
physiological range as these are preferentially oxidized by fish to
generate energy for growth (Bell et al., 2002).