Simple lipids
Simple lipids are composed mainly of triglycerides (98%
fat), in small quantities, and of sterides and cerebrosides.
Glycerides (neutral lipids) consist of triglycerides (98%),
diglycerides (A1.5 0.2%) and monoglycerides (traces).
Gravimetrically, glyceride fatty acids account for almost 90% of the fat. If over 400 compounds have been identified
in bovine milk, only 15 of them are present in substantial
amounts (> 1% of total lipids). The origin of milk fatty acids
is two-fold: fatty acids with carbon chain lengths from 4 to
12 carbon atoms are synthesized by the mammary gland
from blood precursors, fatty acids with carbon chain
lengths 18 (and more) carbon atoms are directly collected
in the blood plasma (they are derived from the diet, the fat
reserves or synthesis in tissues other than the mammary
gland) and fatty acids and 16 to 14 carbon atoms is derived
from de novo synthesis by the udder or a levy in the
bloodstream (Table 7) (Florence, 2010).