Lipid Composition of Hexane and Supercritical Carbon Dioxide Reduced Cholesterol Dried Egg Yolk , ,

Abstract

Cholesterol was extracted from commercially spray-dried egg yolk using hexane at atmospheric pressure or supercritical carbon dioxide (SCCO2) (45 C, 238 atm; 45 C, 306 atm; 55 C, 374 atm). The effects of the different extraction methods on the lipid composition of the cholesterol-reduced yolks were evaluated. Polar lipids were separated into seven fractions using HPLC. Fractions 4, phosphatidylethanolamine (PE), and 5, phosphatidylcholine plus lysophosphatidylethanolamine (PC+LPE), accounted for almost 85% of the phospholipid (PL). As SCCO2 temperature and pressure increased, total lipid remaining decreased from 64.9 to 35.1%, but the PL content (15%) remained unaffected. The proportions of PE (12%) and PC+LPE (72%) of the PL fraction were constant. There was little effect on the fatty acid composition of the phospholipid fractions due to the SCCO2 treatments. However, the unsaturated fatty acids in the neutral lipids (NL) appeared to be effected by SCCO2 treatments. Hexane extracted a larger amount of total lipid (66%) and the NL fraction was decreased more than the PL fraction. Supercritical carbon dioxide was more efficient in removing cholesterol without major effects on the PL.