Аноксомер

Substance identification

Anoxomer is a synthetic polymer antioxidant for food use, registered as additive E323. The formula is written as copolymer (C15H16O2, C10H14O2, C10H14O, C10H10, C7H8O2, C7H8O)x, CAS number 60837-57-2 (related numbers 63748-55-0 and 68438-64-2), trade name Poly-AO 79. Synonyms reflect the composition monomers: 1,4-benzenediol, 2-(1,1-dimethylethyl)-, polymer with diethylbenzene, 4-(1,1-dimethylethyl)phenol, 4-methoxyphenol, 4,4'-(1-methylethylidene)bis[phenol] and 4-methylphenol, and other permutations of the same composition.

Composition and preparation

Anoxomer is obtained by the polycondensation reaction of divinylbenzene (meta- and para-isomers) with a mixture of classical phenolic antioxidants: tert-butylhydroquinone, tert-butylphenol, hydroxyanisole (4-methoxyphenol), 4,4'-isopropylidene diphenol (bisphenol A) and p-cresol (4-methylphenol). The resulting non-absorbable polymer retains antioxidant phenolic groups that are not available for absorption in the gastrointestinal tract.

Physical properties

• Appearance: White powder
• Solubility: insoluble in water and glycols; moderately soluble in alcohols and oils; highly soluble in fatty solvents
• Average molecular weight of the polymer: 4500–5000; no more than 5% of the fraction exceeds 50,000 daltons and no more than 1% is less than 500 daltons
• Specification purity: no less than 98.0% polymer (UV spectrometry method)

Application and regulation

Anoxomer was developed as a way to introduce classical antioxidants (BHA, BHT, TBHQ) into food in a form that is not absorbed during digestion, which reduces the risk of systemic exposure to their metabolic products. According to FDA regulations (21 CFR 172.105), use as an antioxidant in food products is allowed in an amount of no more than 5000 parts per million based on the content of fats and oils in the product. Initial FDA approval dated April 26, 1983, with amendments June 12, 1989 and March 24, 2023. In food labeling it is used under the code E323.

Substance class

Belongs to the class of polymeric phenolic antioxidants; unlike low-molecular antioxidants (BHA, BHT), it is not excreted through the bloodstream and acts locally in the fatty phase of the product and in the gastrointestinal tract.

Mechanism of action and history of study

The antioxidant effect of anoxomer, like its low-molecular-weight predecessors, is based on the ability of the phenolic hydroxyl groups of the polymer to interrupt chain reactions of lipid oxidation by donating a hydrogen atom to free radicals and forming stable phenoxyl radicals. The polymer was developed in the 1970–1980s as a solution to the problem of possible systemic accumulation of metabolic products of classical antioxidants (BHA, BHT, TBHQ) - due to its high molecular weight, anoxomer is practically not absorbed by the intestinal wall and was considered as a safer alternative for stabilizing fat-containing foods, cosmetics and packaging materials in contact with fats.