First identified in egg yolk, ox brain and soybean oil. Present throughout the animal and vegetable kingdoms. Used in food processing as an emulsifier and anti-sticking agent Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can be easily obtained from a variety of readily available sources such as egg yolk or soy beans from which they are mechanically extracted or chemically extracted using hexane. They are also a member of the lecithin group of yellow-brownish fatty substances occurring in animal and plant tissues. (Wikipedia)