Plant phytosterols as modulators of lipid vesicle digestibility in hybrid plant/animal food products

The milk fat globule membrane (MFGM) is a biological membrane enclosing milk fat globules. The components of MFGM are arranged in a trilayer structure. The MFGM is composed of glycerophospholipids, including phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS), sphingolipids such as milk sphingomyelin (SM), cholesterol, and specific proteins found in membranes. Milk-SM, PC, and cholesterol have been found to preferentially reside in the MFGM's outer bilayer. Cholesterol accounts for over 90% of the sterols found in MFGM. The presence of cholesterol modulates the fluidity of the fat globule membrane, which can cause it to rupture and generate more easily digested vesicles. Attractive interactions between cholesterol and sphingomyelin within the MFGM structure occur in a liquid-ordered (Lo) phase surrounded by a phospholipid liquid-disordered (Ld) phase. This lowers the release of cholesterol under digestive conditions and the production of cholesterol plaque.

Phytosterols (PSs), which include plant sterols and stanols, are sterols that are structurally and biologically similar to cholesterol. The primary differences between phytosterols and cholesterol are in the carbon side chain and/or the presence or absence of a carbon double bond.

There has been no research on the effect of gastrointestinal digestion of lipid structures containing MFGM-PS complexes in the absence of cholesterol where sterols are complexed within a liquid-ordered phase. With a growing tendency towards functional plant-based protein- and lipid-based foods, this study seeks to investigate the impact of phytosterols in a cholesterol-removed MFGM on lipid digestibility.