Yolk powder suspensions were reacted with a crude enzyme preparation (Newlase F, which contains protease and lipase). Lipoproteins were decomposed by enzymatic action into water-soluble proteins and peptides, and the reaction mixtures became transparent. On the other hand, lipids (yolk oil) came to the surface of the reaction mixtures. The optimum conditions under which the reaction mixtures became transparent were a shaking frequency of 60 rpm (stroke, 40 mm), an enzyme to yolk powder concentration of 2 mg/50 mg, a reaction temperature of 45-50 degrees C, a reaction mixture pH of 4.0-4.5, and an acetate buffer concentration of 0.1 M. Under these conditions, the lipids were separated and the enzymatic reaction mixtures became transparent in 2-3 h.