The objective of this study was to perform a comparative analysis of the composition
of milk fat globules and
to investigate the lateral organisation of their biomembrane, according to their size.
We revealed biochemical and structural differences as a function of the size of fat globules.
The SMFG-fractions contained significantly
(i) higher amounts of polar lipids,
(ii) lower relative proportions
of PC and SM in the MFGM, (iii) higher amounts of C12:0,
C14:0, C16:0, C18:1 trans, C18:2 c9 tr11, and lower amounts of
C18:0 and C18:1 c9 compared to LMFG-fractions and whole milks.
Regarding the structure of the biomembrane, we revealed, for the
first time, the lateral segregation of SM in rigid liquid-ordered domains
surrounded by the fluid matrix of glycerophospholipids in
the liquid-disordered phase, and the heterogeneous distribution
of glycolipids and glycoproteins. If we keep in mind that milk fat
globules are the natural vehicles secreted by female mammals to
deliver lipids to their infant, it is possible that, among the wide size
distribution of fat globules, small and large milk fat globules may
play different and specific roles in the gastrointestinal tract of
the infants. The specific compositions and structures, revealed
according to the size of milk fat globules, need to be further studied
in regard to their potential physiological, nutritional and health
consequences. Such understanding of milk fat globules properties,
as a function of their size, could lead to the development of foods
with improved health-properties, adapted for populations such
as infants or elderly persons.