PARTIAL LIPID EXTRACTION OF EGG-YOLK POWDER - EFFECTS ON EMULSIFYING PROPERTIES AND SOLUBLE-PROTEIN FRACTION

Egg yolk powder was partly defatted using hexane, 95% ethanol, isopropanol, chloroform-methanol (2:1, v:v) hexane-isopropanol (77:23, w:w) and hexane-ethanol (77:23, w:w). Hexane-isopropanol was most efficient, extracting more than 50% of the lipid. Protein solubility and emulsifying activity of the extracted powder decreased after extraction. Hexane-isopropanol reduced emulsifying activity about 14% and protein solubility to 13.8% from 15.7%. Extraction with other solvents resulted in up to 41% loss of emulsifying activity; protein solubility decreased to as low as 3%. Ovalbumin in the water-soluble fraction of extracted egg yolk powder reduced its emulsifying effectiveness.