Adsorption Behavior of Egg Yolk Low-Density Lipoproteins in Oil-in-Water Emulsions

Adsorption behavior of egg yolk low-density lipoprotein (LDL) constituents in oil-in-water emulsions (20% triolein) was examined. The mean particle size was decreased with increase in LDL concentrations and reached a plateau at 60 mg/mL of LDL concentrations. The average particle size and concentration of lipoproteins at the interface were greater for emulsions made at pH 3.0 and 5.0 than at pH 7.0 and 9.0, resulting from the formation of lipoprotein dimers at acid pHs. Electrophoretic analysis revealed that the three polypeptides (64, 43, and 19 kDa) in LDL constituents did not adsorb at the interface, independent of the LDL concentration, pHs, and NaCl content. On the other hand, cholesterol in LDL was preferentially adsorbed to the interfaces at the low LDL concentration. The ratio of phosphatidylcholine and phosphatidylethanolamine was increased with increased of LDL concentration. These results suggest that egg yolk LDL micelles breakdown when the micelles come into contact with the interface and rearrangement of lipoproteins, cholesterol, and phospholipids take place following adsorption at an O/W interface.