What is the difference between natural and artificial emulsifiers?

Germany

Emulsifiers currently used in food production are either purified natural products (like e.g. egg yolk used as an emulsifier in mayonnaise) or synthetic chemicals that have very similar structures to the natural products and are classified as food additives.

Emulsifiers are molecules with one water soluble (hydrophilic) and one oil soluble (hydrophobic) end. They make it possible for mixtures of water and oil to become finely dispersed, creating a stable, homogenous, smooth emulsion.

Egg yolk was probably the first emulsifier ever used in ‘food production’ back in the early 19th century. Because emulsifiers in egg yolk break down rather rapidly, manufacturers have switched to more stable emulsifiers. Nowadays, emulsifiers are important food additives for the manufacturing of numerous food products such as margarine, mayonnaise, creamy sauces, candy, many packaged and processed foods, confections, and a range of baked goods.

An extensive check on the safety of all additives must be carried out before they are allowed in food. The use of food additives is subject to stringent EU legislation governing their safety assessment, authorisation, use, and labelling: Directive 95/2/EC of the European Parliament and the Council of 20 February 1995 on Food Additives other than Colouring and Sweeteners. These legislations require all added emulsifiers, as well as all other food additives, to be declared on food packaging with either their name or E-number.

See Foodtoday Article No. 48-3:

The perfect mixture: emulsifiers make our food enjoyable
http://www.eufic.org/gb/food/pag/food48/food483.htm