408 Chapter 16
and its products EPA (eicosapentaenoic acid)
and DHA (docosahexaenoic acid), although
present in trace amounts, exert a signifi cant
physiological role.
The physiological attributes of milk fat
are attributed to its fatty acid make - up. More
than 400 distinct fatty acids have been
detected in milk. Table 16.17 shows the fatty
acid composition of the fat of milk and butter
(Jensen, 1995 ).
Typically, the fat in milk consists of 65%
saturated, 23% monounsaturated, and 10%
polyunsaturated fatty acids. Because of frac-
tionation during the butter - making process,
the fat of butter consists of 66% saturated,
23% monounsaturated and 4% polyunsatu-
rated fatty acids.
The roles of the various fatty acids and
other milk fat constituents in human health
are discussed below.et al., 2002 ). Vitamin A performs important
roles in vision, body growth, reproduction,
bone metabolism, and immune function.
Vitamin D is essential for a healthy skeleton
and is involved in absorption of calcium and
phosphorus in the gastrointestinal tract.
Vitamin E works as an antioxidant that pro-
tects cell membranes and lipoproteins from
oxidative deterioration by free radicals. It
also stimulates the immune system and helps
maintain cell integrity. Vitamin K is vital for
blood clotting function and may play a role
in bone protection.
Milk fat also is a source of essential fatty
acids and linolenic acids. Essential fatty
acids are not synthesized by human body in
required amounts, thus, they must be sup-
plied by the diet. Arachidonic acid with four
double bonds is present in traces. Its precur-
sor is linoleic acid. Omega - 3 - linoleic acid
Table 16.17. Fatty acid composition of bovine milk fat.
Type Number of
carbon atoms *Systematic name Common name % Weight
in milk% Weight
in butter
Saturated fatty
acids4:00 Butanoic acid Butyric acid 4.5 5.31
6:00 Hexanoic acid Caproic acid 2.3 2.81
8:00 Octanoic acid Caprylic acid 1.3 1.56
10:00 Decanoic acid Capric acid 2.7 3.14
12:00 Dodecanoic acid Lauric acid 3.0 3.39
14:00 Tetradecanoic acid Myristic acid 10.6 10.78
16:00 Hexadecanoic acid Palmitic acid 28.2 28.13
18:00 Octadecanoic acid Stearic acid 12.6 10.62
20:00 Eicosanoic acid Arachidic acid 0.20 0.20
Monounsaturated
fatty acids14:1 Tetradecenoic acid Myristoleic acid 0.9 0.9
16:1 Hexadecenoic acid Palmitoleic acid 1.8 1.38
18:1 Octadecenoic acid Oleic acid 21.4 20.84
20:1 Eicosenoic acid Gadoleic acid 0.6 0.29
22:1 Docosenoic acid Erucic acid — 0.09
Polyunsaturated
fatty acids18:2 Octadecadienoic acid Linoleic acid 3.3 2.72
18:3 Octadecatrienoic acid Linolenic acid 3.2 0.56
18:3
n - 3— α - linolenic acid 0.3 0.48
18:3
n - 6— γ - linolenic acid 2.9 0.08
18:4
n3Octadecattetraenoic acid Parinaric acid — 0.27
20:2 Eicosadienoic acid — — 0.03
20:3 Eicosatrienoic acid — — 0.10
20:4
n6Eicosatetraenoic acid Arachidonic acid 0.2 0.14- Number of carbon atoms, followed by number of unsaturated bonds in the molecule.
Adapted from: Jensen (1995)