Extraction of Lipids and Functional Properties of Defatted Egg Yolk Powder Obtained Using a One-Step Organic Solvent Lipid Extraction Process.

A one-step organic solvent lipid extraction method was used to separate lipids from spray-dried egg yolk. Organic solvents tested were chloroform:methanol (CM, 2:1, :), methyl-tert-butyl ether (MTBE), or hexane:isopropanol (HI, 3:2, :). The resulting defatted egg yolk powder had between 21 and 30% more protein and between 22 and 25% less lipid than the initial spray-dried egg yolk powder ( < 0.05). The solubility of the powder decreased from 20% to 4% ( < 0.05) when CM was used as the organic solvent, likely due to protein denaturation by the chloroform. Gels made from MBTE and HI-extracted protein concentrates had similar hardness ( > 0.05) and were both harder than gels made using the initial egg yolk powder ( < 0.05). MTBE gels were springier, more cohesive, and gummier ( < 0.05) with similar resistance to the initial egg yolk powder ( > 0.05). The results of this study showed that the functionality of the protein in the defatted egg yolk powder was best retained when MTBE was used as the lipid extraction solvent.