Lecithin, also known as phosphatidylcholine, is a grease formed by dehydration condensation of glycerol, fatty acid (two molecules), phosphoric acid and choline. The fatty acid chain in the molecule is saturated and unsaturated, and it is a nonpolar hydrophobic tail; Choline phosphate is a dipolar ion, which is a polar hydrophilic head and is known as the "third nutrient" after protein and vitamins. It is the material basis of life and the basic raw material of various cell membrane structures. It exists in every cell, and is more concentrated in liver, brain, heart, kidney and immune system. It is synthesized by liver in human body, and food mainly exists in soybean and egg yolk...