UK legislation on additives is generally derived from rules established at a European Union level to ensure that impediments to trade are not created within the EU. The Food Additives (England) and the Extraction Solvents in Food Regulation has recently been ammended and the ammended regulation came into force on 23 May 2012. The aim of this legislation is to ensure that additives are used only if they perform a useful purpose, are safe and do not mislead the consumer.
In theory there is a large range of additives that can be used in flour as they are permitted in any food. In practice the range is very small. The most common additive for flour is E300 (ascorbic acid, or vitamin C). This is used because it helps bread rise more consistently and is normally added only to specific breadmaking flours supplied to commercial bakeries. Also permitted is E920 (L cysteine hydrochloride). This is derived from synthetic sources; again it is not normally added to flour, but is used in the manufacture of some types of bread. Colours are not permitted in flour. Where used, additives are listed on the packaging of flour and products containing flour.