Food Lipids: Chemistry, Nutrition, and Biotechnology

Table 6 Production and Disappearance (Million Metric Tonnes) of Butter on a Fat Basis
for Selected Countries, 1995–1999
Country
Production
1995 96 97 98 99
Disappearance
1995 96 97 98 99
World 5.68 5.65 5.69 5.74 5.83 5.73 5.66 5.72 5.75 5.81
EU-15 1.56 1.60 1.56 1.58 1.59 1.42 1.52 1.47 1.51 1.53
USSR 0.69 0.54 0.48 0.46 0.45 0.83 0.64 0.64 0.56 0.51
E. Europe 0.21 0.21 0.20 0.21 0.20 0.19 0.17 0.19 0.19 0.18
USA 0.47 0.43 0.43 0.39 0.43 0.45 0.42 0.42 0.40 0.44
India 1.15 1.20 1.24 1.28 1.30 1.15 1.20 1.25 1.28 1.31
Pakistan 0.37 0.39 0.41 0.42 0.43 0.37 0.39 0.42 0.42 0.43
New Zealand 0.23 0.25 0.29 0.29 0.29 0.03 0.03 0.03 0.03 0.03
Most of the saturated acids (C 4–C 14 and about one-half of the C 16) are produced
by de novo synthesis in the mammary gland while the rest of the C 16 and the saturated
and unsaturated C 18 acids are derived from dietary sources or by mobilization of
body fat reserves during early lactation. It follows that only this half of milk fat fatty
acids is subject to change by modification of dietary intake. Furthermore, since in
ruminants (free) unsaturated acids are subject to biohydrogenation in the rumen, it
is necessary to protect such acids during their passage through the rumen if these
are to be incorporated unchanged in the milk fat. This was first achieved through
coating the oil/fat (soybean, linseed, rapeseed/canola), but two other methods are
now more commonly employed. In the first, calcium salts are used as lipid source.
These remain as (unreactive) salts in the rumen but are converted to acids in the
more acidic conditions of the abomasum and enter the duodenum as fatty acids
available for digestion. Alternatively, the lipid is hardened to the point where it
remains solid in the rumen but melts in the abomasum. The resulting changes in the
milk fat may seem small in terms of fatty acid composition, but are slightly greater
in their effect on triacylglycerol composition and may be sufficient to allow the butter
to spread directly from the refrigerator. It is important that the supplement contain
appropriate proportions of n-9, n-6, and n-3 unsaturated acids and that it is over 75%
protected from metabolism in the rumen (14,15).
In times of oversupply there is an interest in extending the range of applications
of milk fat by fractionation. However, the triacylglycerol composition of milk fat is
so complex (no individual triacylglycerol exceeds 5%) that differences between crystallized
fractions are not so marked as with simpler vegetable oils, such as palm oil.
Table 7 Major Fatty Acids (% wt) in Cow’s Milk Fat
Month 4:0 6:0 8:0 10:0 12:0 14:0 16:0 18:0 20:0 18:1 18:2 Other
June 4.2 2.5 2.3 2.2 2.4 9.0 22.1 14.3 2.6 30.4 1.2 6.8
December 3.5 2.2 1.1 2.6 2.8 10.6 26.0 11.6 2.3 24.8 2.8 9.7
Average 3.6 2.2 1.2 2.8 2.8 10.1 25.0 12.1 2.1 27.1 2.4 8.6
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