Metatartaric acid
A heat-treated form of tartaric acid used only in wine to stop gritty tartrate crystals forming in the bottle.
What is it?
Metatartaric acid is produced by heating tartaric acid (the natural acid found in grapes) until some of its molecules link together into short chains. It is a partially esterified, oligomeric form of tartaric acid. Once consumed, it breaks down back into tartaric acid in the body.
What does it do?
In wine, metatartaric acid wraps around tiny crystals of calcium tartrate and potassium hydrogen tartrate (cream of tartar), coating them and preventing them from clumping into the visible gritty deposits that sometimes appear in bottles. The effect is temporary: the molecule slowly hydrolyses over months, especially if wine is stored warm, which is why cold-stabilisation is still preferred for long-lived wines.
Where you will see it
Used exclusively in wine production. It is not permitted in any other food category. Most consumers will not see it listed because EU and UK wine labelling rules historically gave limited ingredient disclosure for wine, though from 2023 EU rules introduced mandatory ingredient and nutrition labelling for wine; UK rules post-Brexit remain under review. If declared, it appears as 'metatartaric acid' or 'E353'.
What the science says
Breakdown and metabolic fate
Metatartaric acid hydrolyses readily in water and in the gut back into ordinary tartaric acid. Tartaric acid is a natural grape constituent that humans have consumed for thousands of years and is also an approved food additive (E334) in its own right. There is no evidence that the heat-treated oligomeric form behaves differently in the body from its parent acid once digested.
EFSA's 2020 re-evaluation concluded that metatartaric acid hydrolyses to tartaric acid under physiological conditions, and that exposure from its permitted use in wine at 100 mg/L is well within the established acceptable daily intake for tartaric acid of 30 mg/kg body weight per day.
Genotoxicity and long-term toxicity
EFSA reviewed the available toxicological data in 2020. No genotoxicity was identified, and no carcinogenicity or reproductive concerns were raised. The panel noted that the short-chain ester structures in metatartaric acid degrade to tartaric acid and do not represent a novel toxicological entity.
The EFSA 2020 re-evaluation found no genotoxic potential for metatartaric acid and concluded that the exposure from authorised use in wine did not raise a safety concern.
No numerical ADI set
EFSA did not set a specific numerical ADI for metatartaric acid as a standalone compound. Because it converts entirely to tartaric acid after consumption, the existing ADI for tartaric acid (30 mg/kg body weight per day) covers any exposure. Actual intake from wine at 100 mg/L is a small fraction of that limit.
No separate numerical ADI was established for E353; dietary exposure is bounded by the tartaric acid ADI of 30 mg/kg body weight per day, which is not approached through permitted wine use.
Where it stands with the regulators
Who should be careful
No specific group needs to avoid metatartaric acid. People who avoid alcohol for health, religious or other reasons will not encounter it, as it is used only in wine. The additive itself does not trigger sulphite sensitivity or other known additive intolerances. Look for 'E353' or 'metatartaric acid' on a wine ingredient declaration.
The honest read
Metatartaric acid is one of the more straightforward entries in the additive register. It is a chemically modified form of a natural grape acid, used in a narrow slice of food production (wine only), at low concentrations, and it converts back to its parent acid after consumption. The 2020 EFSA re-evaluation, the most recent independent scientific review, raised no concerns and set no new restrictions. The science here is not contested or unsettled.
Related additives
Common questions
Is E353 banned in the UK?
No. Metatartaric acid is on the UK FSA approved-additives list and is permitted in wine at up to 100 mg per litre, carrying over from assimilated EU food additive law.
Why is metatartaric acid used in wine instead of just leaving the crystals?
Tartrate crystals in wine are harmless but look like broken glass or grit, which alarms consumers. Winemakers either cold-stabilise (chilling wine to precipitate crystals before bottling) or add metatartaric acid to inhibit crystal growth. The chemical route is quicker and cheaper, though it is less permanent than cold stabilisation.
What foods contain E353?
Only wine. Metatartaric acid is not permitted in any other food category under UK or EU food additive rules.
Is E353 vegan?
Metatartaric acid itself is derived from tartaric acid, which comes from grape processing, and contains no animal-derived ingredients, so the additive is vegan. Whether a specific wine is vegan depends on other fining agents used in production, not on this additive.
Sources
- EFSA Panel on Food Additives and Flavourings: Re-evaluation of metatartaric acid (E 353) as a food additive, EFSA Journal 2020;18(2):6031
- UK FSA: Approved additives and E numbers
- EU Regulation 1333/2008 on food additives, Annex II
- EU Regulation 2019/934 laying down certain oenological practices (wine-specific authorisations)
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