E-numbers / Other additives / E930
also: calcium dioxide · E930
A chemical bleach and dough strengthener used in flour in some countries, but not a permitted food additive in the UK or EU.
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Not permitted in UK or EU food.
Why it’s worth knowing. Not permitted in UK or EU food. If you see it on an imported product, that product may not meet UK or EU food law. Calcium peroxide releases hydrogen peroxide during processing, which can irritate tissue at high concentrations.
Calcium peroxide (CaO2) is an inorganic oxidising compound, a white powder that slowly releases oxygen and hydrogen peroxide when it contacts moisture. It is a close relative of calcium oxide (quicklime) but carries extra oxygen atoms that make it an oxidant.
In flour and dough, the oxygen released by calcium peroxide oxidises the sulphydryl groups in gluten proteins, forming disulphide bonds that tighten and strengthen the gluten network. This makes dough more elastic and easier to machine. At the same time, the bleaching action oxidises carotenoid pigments in flour, whitening it. The reaction is relatively rapid compared with other flour oxidants such as ascorbic acid.
Used commercially in the United States and some Asian and South American markets as a flour treatment agent and dough conditioner in bread, rolls, and other baked goods. It is not approved in the UK or EU, so it should not appear on any UK food label. In countries where it is permitted, it appears on labels as 'calcium peroxide' or as part of 'flour treatment agent' declarations.
The UK Food Standards Agency's approved additives list does not include E930. EU Regulation 1333/2008 Annex II, which is the positive list of permitted food additives, also does not authorise calcium peroxide. Both regulatory frameworks operate on a positive-list basis: if an additive is not listed, it cannot legally be used in food sold in the UK or EU.
E930 is absent from the UK FSA's approved-additives list, which runs from E927b directly to E938 with no entry for E930.
EU Regulation 1333/2008 Annex II does not include calcium peroxide as a permitted food additive in any food category.
Calcium peroxide is an oxidant. When it contacts moisture in dough, it hydrolyses to release calcium hydroxide and hydrogen peroxide. Hydrogen peroxide at high concentrations is an irritant to mucous membranes and the gastrointestinal tract. In baking applications the peroxide is largely consumed during the reaction with flour proteins, meaning residual levels in the finished baked product are low, but the safety of residuals was a consideration in regulatory evaluations.
Calcium peroxide decomposes in the presence of water to release hydrogen peroxide, which at elevated concentrations is cytotoxic and mucosal irritant.
Flour-treatment doses of calcium peroxide (typically 20-75mg/kg of flour) result in low residual hydrogen peroxide in baked products, but full degradation depends on baking conditions.
The United States FDA permits calcium peroxide for use in flour as a dough conditioner. Some Asian markets also allow it as a flour treatment agent. Its use in these contexts is at low levels and subject to manufacturing practice limits. The EU and UK took a more cautious approach and did not place it on their permitted lists, reflecting a precautionary stance on oxidising agents in processed foods.
The US FDA lists calcium peroxide as a permitted flour treating agent under 21 CFR 137.105, with a maximum level of 75 parts per million in flour.
Because E930 is not permitted in UK or EU food, shoppers in the UK should not encounter it in products bought here. If purchasing imported bread, baked goods, or flour products from the United States or certain Asian countries, check the label for 'calcium peroxide' or 'flour treatment agent'. People with gastrointestinal sensitivities may wish to note that it is an oxidising agent that releases hydrogen peroxide during processing.
E930 is a functioning flour conditioner used in industrial baking in the US, where regulatory bodies have accepted it at low levels. The EU and UK chose not to authorise it, in line with a narrower positive list that admits fewer oxidising agents than US food law. The science on residual hydrogen peroxide levels in finished baked goods at approved use rates is not alarming, but the EU regulatory position is that authorisation requires demonstrating technological need and safety to a committee's satisfaction, and that case was not made for the EU market. Shoppers in the UK are very unlikely to encounter E930 in any food they buy from a UK or EU retailer.
It is not on the UK's approved-additives list, which means it cannot legally be used in food sold in the UK. The UK (like the EU) operates a positive list: only additives that have been authorised and listed may be used. E930 is not on that list and is therefore prohibited in practice, even if no formal ban order was issued.
It releases oxygen and hydrogen peroxide when mixed into dough. The oxygen tightens gluten proteins, making dough more elastic and machine-friendly. The hydrogen peroxide bleaches the natural carotenoid pigments in flour, producing a whiter crumb. Both effects are sought by industrial bakers processing large volumes of bread.
In the UK and EU, no legally sold food should contain E930. In the United States, it may be used in bread, rolls, and other baked goods as a dough conditioner. Imported products from the US or some Asian countries are the main context where a UK shopper might encounter it.
Calcium peroxide is an inorganic mineral compound with no animal-derived ingredients. It would be considered vegan by standard definitions.
Last reviewed: 20 June 2026
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