For both buttermilks and butter serums, no milk fat globules with a
size above 1 μm were observed after the technological step of skimming
(Fig. 3). This meant that the large milk fat globules (size above 1 μm)
were removed by centrifugation during the skimming step due to
their lower density attributed to their high content in TAG. However,
skimming processing had no effect on small milk fat globules (size
below 1 μm),MFGM fragments and case in micelles that remain present
in both buttermilk and butter serum. Also, we showed that the skimming
step had no effect on milk polar lipid vesicles observed in the butter
serums (Fig. 6D).