© 2012 AOAC INTERNATIONAL
could be the following: Incomplete transesterification, partial
degradation of one internal standard, or matrix effect.
J. Annex A: Groups or Class of Fatty Acids and Individual Fatty
Acids
(
a
)
Group or class of fatty acid
.
(
1
)
Trans fatty acids (TFA)
.—TFA is the sum of fatty acids
containing one or more nonconjugated double bonds in
trans
configuration (only C18:1, C18:2, and C18:3
trans
are included in
the sum).
Note
: Presence of other
trans
isomers naturally present in
milk fat have been reported in literature (e.g., C16:1), but their
contributions have no significant influence on the total amount of
trans
in milk products. In addition, their identification are complex
especially because these isomers are frequently interfered with
other isomers (e.g.,
cis
,
iso
, and
anteiso
) and need preliminary
separation technique.
(
2
)
Conjugated linoleic acids (CLA)
.—CLA are the sum of
octadecadienoic acids containing conjugated double bonds in
cis
or
trans
configuration; mainly
cis
-9,
trans
-11 octadecadienoic acid
(i.e., rumenic acid).
(
3
)
Saturated fatty acids (SFA)
.—SFA are the sum of all fatty
acids which contain no double bonds.
(
4
)
Monounsaturated fatty acids (MUFA)
.—MUFA are the sum
of all fatty acids containing one double bonds in
cis
configuration.
(
5
)
Polyunsaturated fatty acids (PUFA)
.—PUFA are the sum
of all fatty acids containing two or more double bonds in
cis
configuration.
Note
: LC-PUFA is the generic name to describe the long-chain
polyunsaturated fatty acids, but these fatty acids are also included
into PUFA(i.e., arachidonic, ecosapentaenoic, and docosahexaenoic
acids).
(
6
)
Omega-3 fatty acid (ω-3)
.—Omega-3 fatty acid is the sum
of
cis
PUFA having the first double bonds at carbon (n-3) from the
terminal methyl group.
(
7
)
Omega-6 fatty acid (ω-6)
.—Omega-6 fatty acid is the sum
of
cis
PUFA having the first double bonds at carbon (n-6) from the
terminal methyl group.
(
8
)
Omega-9 fatty acid (ω-9)
.—Omega-3 fatty acid is the sum
of
cis
PUFA having the first double bonds at carbon (n-9) from the
terminal methyl group.
(
b
)
Individual fatty acids
.
(
1
)
Linoleic acid (LA)
.—LA is an essential fatty acid; an 18
carbon fatty acid containing two double bonds at carbons 9 and 12.
(
2
)
Linolenic acid (ALA) also called α-linolenic acid
.—ALA
is an essential fatty acid; an 18 carbon fatty acid containing three
double bonds at carbons 9, 12, and 15.
(
3
)
Arachidonic acid (ARA)
.—ARA is not an essential fatty
acid; a 20 carbon fatty acid containing four double bonds at carbons
5, 8, 11, and 14.
(
4
)
Ecosapentaenoic acid (EPA)
.—EPA is a semi-essential fatty
acid (essential for pregnant woman and infant); a 20 carbon fatty
acid containing five double bonds at carbons 5, 8, 11, 14, and 17.
(
5
)
Docosahexaenoic acid (DHA)
.—DHA is a semi-essential
fatty acid (essential for pregnant woman and infant); a 22 carbon
fatty acid containing six double bonds at carbons 4, 7, 10, 13, 16,
and 19.
Reference:
J. AOAC Int
. (future issue)
