<P> Phospholipids can act as emulsifiers, enabling oils to form a colloid with water . Phospholipids are one of the components of lecithin which is found in egg - yolks, as well as being extracted from soy beans, and is used as a food additive in many products, and can be purchased as a dietary supplement . Lysolecithins are typically used for water - oil emulsions like margarine, due to their higher HLB ratio . </P> <Dl> <Dd> See table below for an extensive list . </Dd> </Dl> <Dd> See table below for an extensive list . </Dd> <Ul> <Li> Natural phospholipid derivates: <Dl> <Dd> egg PC (Egg lecithin), egg PG, soy PC, hydrogenated soy PC, sphingomyelin as natural phospholipids . </Dd> </Dl> </Li> <Li> Synthetic phospholipid derivates: <Ul> <Li> Phosphatidic acid (DMPA, DPPA, DSPA) </Li> <Li> Phosphatidylcholine (DDPC, DLPC, DMPC, DPPC, DSPC, DOPC, POPC, DEPC) </Li> <Li> Phosphatidylglycerol (DMPG, DPPG, DSPG, POPG) </Li> <Li> Phosphatidylethanolamine (DMPE, DPPE, DSPE DOPE) </Li> <Li> Phosphatidylserine (DOPS) </Li> <Li> PEG phospholipid (mPEG - phospholipid, polyglycerin - phospholipid, funcitionalized - phospholipid, terminal activated - phospholipid) </Li> </Ul> </Li> </Ul>

What is the function of a hydrophilic head