The polar groups are the ones that provide the hydrophilic character.
Explanation:
In an emulsifying agent, there will be always a part that is hydrophyllic (the polar part) and another part that is lipophyllic (the non - polar part). Depending the proportion of each group the emulsifying agent is consider with a value that goes from 0 to 20, that means, if is more useful to dissolve water into oil or the other way around.
Since in this chemical groups, there is a lot of charges, depending in the reaction the pH could change a little bit by the release of positive or negative charges of the emulsifying agent.
