Allervibe
E223
Sodium metabisulphite
A white crystalline salt that releases sulphur dioxide in water and is the most widely used sulphite preservative.
i Additive Details
| Is E223 Sodium metabisulphite safe?
Sulphites are one of the 14 allergens that must be declared under EU Regulation 1169/2011 whenever they are present above 10 mg/kg or 10 mg/litre expressed as SO2. Sulphite sensitivity is well documented in people with asthma, who may react with wheezing, chest tightness or bronchospasm. Most sulphite reactions are intolerance rather than classical IgE-mediated allergy, although rare IgE-mediated cases have been reported. Prawns and shrimp treated to prevent black spot are a frequent source of unexpected exposure, and E223 is the sulphite listed most often on packaged foods.
| Uses
Releases roughly two thirds of its weight as sulphur dioxide, which makes it an efficient dry source of sulphite. Used in dried fruit and vegetables, wine, cider and beer, fruit juices, pickles and dehydrated potato products, and in the UK in burger meat and sausages. It is also applied to prawns and shrimp to stop black spot, and used in biscuit and cracker doughs as a reducing agent that relaxes gluten.
| Interactions
In water it hydrolyses to bisulphite, so it behaves like the other sulphites, binding aldehydes and ketones, blocking browning and slowly destroying thiamine (vitamin B1). In wine part of it is bound by acetaldehyde, which lowers the free SO2 available for preservation and is why winemakers measure free and total SO2 separately.
| Origin
Made by saturating a sodium carbonate or sodium hydroxide solution with sulphur dioxide and crystallising the metabisulphite. The dry salt is stable enough to store and ship, but it loses sulphur dioxide over time and smells strongly of it when damp.
| Daily Intake
A group ADI of 0.7 mg per kg of body weight per day, expressed as SO2, applies jointly to E220 to E228 rather than to each salt individually. EFSA's 2022 follow-up to its re-evaluation of the group concluded that the available data are not sufficient to confirm the ADI and that estimated intake can exceed it in some consumer groups.
Information is sourced from public regulatory bodies (EFSA, FDA, WHO) and is for reference only. Always read the package and consult a healthcare professional for medical advice.
Related additives
- E1105 Lysozyme An enzyme isolated from hen egg white that breaks down the cell walls of Gram-positive bacteria.
- E221 Sodium sulphite A soluble sodium salt of sulphurous acid used as a preservative and antioxidant.
- E222 Sodium bisulphite The sodium salt of hydrogen sulphite, supplied as an aqueous solution and used as a preservative and antioxidant.
- E224 Potassium metabisulphite The potassium form of metabisulphite, used mainly as a preservative and antioxidant in wine and cider.
- E226 Calcium sulphite A calcium salt of sulphurous acid with low water solubility, used as a preservative and antioxidant.
- E227 Calcium bisulphite A calcium sulphite that exists only in solution, used as a preservative and antioxidant.
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