Nutritional Aspects of Polar Lipids from Milk Phospho- and Glycolipids
Polar lipids extracted from the milk fat globule membrane have a unique composition, different from all other commercially available phospholipid products. Main polar lipids are phosphatidylcholine, phosphatidylethanolamine and sphingomyelin. Important from a nutritional point of view are also the minor components as for example ceramides and gangliosides.
This highly active nutritional cocktail shows manifold health benefits especially in infant nutrition protecting the sensitive digestive system, improving immunity and brain development.
A particular section is about the analyis of gangliosides
The polar lipids in milk are part of the emulsifying principle of the milk fat globule membrane (MFGM), protecting the milk droplets from coalescence and enzymatic degradation. Besides membrane specific proteins the major components of the MFGM are glycerophosphospho- and sphingolipids both of which should be the topic of this article.
Glycerophospholipids consist a glycerol backbone with two fatty acids esterified and a phosphoric acid ester bound to the third position. The phosphoric acid ester is also bound to a small hydroxyl group bearing molecule like choline, ethanolamine etc.
The following picture schematically shows the molecular organisation with its bipolar emulsifying nature.
The characteristic structural unit of Sphingolipids however is the spingosine base, a long chain aliphatic amine, carrying two hydroxyl groups (Figure 2). When the amino group is bound to a fatty acid the molecule is called a ceramide. Sphingophospholipids are substances with a phosphoric acid ester bound to the hydroxyl group of ceramides. If instead of the phosphoric acid ester a carbohydrate is bound the molecules are call ...