Food additives are chemicals that are added to foods to improve or maintain their shelf-life or appearance, consistency, taste, smell, etc. In the law, additives are substances, regardless of their nutritional value, which are generally not used alone or as a foodstuff or as a characteristic food additive and added to foodstuffs during production, packaging, transport or storage, whereby they or their by-products become or may become part of the foodstuff.
E300-E399 antioxidants, acidity regulators
E400-E499 emulsifiers, thickeners, stabilizers
E500-E599 anti-caking agents, acidity regulators, fillers
E600-E699 flavor and smell enhancers
E900-E999 polishing substances, sweeteners, packaging gases, propellants
E1000-E1999 other substances
More info at: http://bit.ly/additves