E-numbers / Other additives / E928
also: dibenzoyl peroxide · E928
A chemical bleaching agent once used to whiten flour. Not a permitted food additive in the UK or EU.
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Benzoyl peroxide is not authorised for use in UK or EU food.
Why it’s worth knowing. Benzoyl peroxide is not authorised for use in UK or EU food. If you see it listed on an imported product, the food does not meet UK or EU food law.
Benzoyl peroxide is a strong oxidising chemical. In food use it was applied as a flour treatment agent: it oxidises the yellow carotenoid pigments in freshly milled wheat flour, bleaching the flour white within days rather than the weeks natural ageing requires. The same compound is widely used in acne skincare products and as an industrial bleach.
When added to flour, benzoyl peroxide reacts rapidly with the carotenoid pigments responsible for the naturally yellowish colour of unaged flour. The oxidation destroys the pigments and produces a whiter flour. It breaks down to benzoic acid in the process, which itself is E210, a permitted preservative in other food uses. The bleaching reaction does not meaningfully improve baking performance; it is cosmetic.
Not used in UK or EU food products. In countries where it remains permitted, primarily the United States and parts of Asia, it appears in white bread flour, cake flour, and some baked goods made with bleached flour. On a US ingredient label it may appear as 'bleached flour' (the bleaching agent itself is not always named) or as 'benzoyl peroxide' in the additives declaration.
When the EU consolidated its food additive rules into Regulation 1333/2008, benzoyl peroxide was not included in the approved list (Annex II). The UK's post-Brexit framework retains the same list. The absence reflects a precautionary position: the EU did not consider the cosmetic benefit of whiter flour to outweigh the need to carry an oxidising chemical into the food supply. Bleached flour has been effectively banned in the EU since before the 2008 regulation codified the list.
Benzoyl peroxide does not appear in Annex II of EU Regulation 1333/2008 (the exhaustive list of permitted food additives), meaning it has no authorised use in any food category in the EU or the UK.
Benzoyl peroxide reacts in flour to produce benzoic acid. Benzoic acid is E210, a permitted preservative in certain foods at controlled levels. In bleached flour the residual benzoic acid levels are low, but the conversion is complete and measurable. Regulatory frameworks that permit benzoyl peroxide in flour (such as the US FDA) consider the residual benzoic acid acceptable under good manufacturing practice limits.
Benzoyl peroxide decomposes to benzoic acid when used as a flour bleaching agent; the residual benzoic acid is the primary reaction product detectable in bleached flour.
The US FDA lists benzoyl peroxide as generally recognised as safe (GRAS) as a bleaching agent in flour at levels consistent with good manufacturing practice, with benzoic acid as the accepted residue.
The carotenoid pigments that benzoyl peroxide destroys include beta-carotene and lutein, compounds with antioxidant and nutritional value. Bleaching removes these from the flour. This is one reason nutritional and food science commentary notes that bleached flour is nutritionally inferior to unbleached flour in this respect, though the absolute amounts in flour are small.
Chemical bleaching of flour with benzoyl peroxide destroys naturally occurring carotenoid pigments including beta-carotene and xanthophylls, reducing the antioxidant content of the flour.
Anyone buying imported flour or baked goods from the US should be aware that US 'bleached flour' products may contain residual benzoic acid from benzoyl peroxide treatment. Products sold in the UK and EU must use unbleached flour or alternative permitted treatments. Look for 'bleached flour' or 'benzoyl peroxide' on labels of US-origin products.
The main fact here is regulatory, not toxicological: the UK and EU simply do not permit this chemical in food, so shoppers buying UK or EU-labelled products will not encounter it. The scientific debate is modest. The compound is a strong oxidiser and breaks down to benzoic acid, and some animal studies at high doses have raised questions, but the realistic food-exposure route in the UK is zero. The concern that matters in practice is provenance: if an imported product from a country that permits bleached flour enters the UK market without proper declaration, it would be non-compliant with UK food law. The EU and UK position is not primarily a toxicological verdict; it is that there is no demonstrated need for a cosmetic whitening agent in food.
It is not on the UK's list of approved food additives, which means it cannot legally be used in food sold in the UK. The UK Food Standards Agency approved additives list (which mirrors the EU framework retained after Brexit) does not include E928. 'Not permitted' is the accurate term rather than 'banned', but the practical effect is the same: food sold in the UK cannot contain it.
When the EU drew up its definitive permitted-additives list under Regulation 1333/2008, benzoyl peroxide was not included. The EU position was that the benefit, making flour whiter faster, was cosmetic and did not justify authorising an oxidising chemical in food. The UK retained this position after Brexit.
No foods legally sold in the UK or EU contain E928. In the United States it is permitted as a bleaching agent in white flour, cake flour, and products made from bleached flour. US-origin packaged baked goods or flour imported informally may contain it.
Benzoyl peroxide itself is a synthetic chemical with no animal-derived ingredients. Vegan status is not the relevant consideration for this additive in the UK, as it is not a permitted food additive here.
Last reviewed: 20 June 2026
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