Changes of Choline-containing Phospholipids in Quail's Egg during Pidan-Making

Abstract

For making pidan from quail's egg, the eggs were immersed in the brine consisting of 5% sodium hydroxide, 10% sodium chloride and 2% black tea for 14 days at 25°C. After the immersing, the eggs were fished out to be allowed to ripening for 7 days at room temperature. In the egg yolk, the amounts of choline-containing lipids decreased rapidly to 14% of that contained in fresh yolk during the immersing period, while the amounts of glycerophosphorylcholine increased gradually to a maximum value on the 14th day of the immersing. In the egg white, both the amounts of glycerophosphorylcholine and free choline increased gradually from the 3rd day of the immersing. The phosphatidylcholine prepared from fresh egg yolk was incubated with 0.5 N aqueous solution of sodium hydroxide at 30°C. The lipid was hydrolyzed rapidly, and formed glycerophosphorylcholine and free choline. After 9hr of the incubation, the conversion of the lipid to glycerophosphorylcholille and free choline were 25% and 55% respectively. Hydrolysis of glycerophosphorylcholine in the alkaline solution was also studied. These results suggest that a hydrolytic pathway of phosphatidylcholine in the egg yolk during pidan-making is as follows, phosphatidylcholine→lysophosphatidylcholine→glycerophosphorylcholine→free choline.