E500 - Sodium carbonates
What it is and how it is used
E 500 covers three related sodium carbonates: sodium carbonate proper (soda ash, E 500(i)), sodium hydrogen carbonate (bicarbonate of soda, E 500(ii)) and sodium sesquicarbonate (E 500(iii)). Most kitchen encounters are with the second. Industrially they come from the Solvay process, which turns salt and limestone into soda ash.
Bicarbonate raises baked goods by decomposing into carbon dioxide when it meets acid or heat — it needs an acid partner such as cream of tartar or buttermilk, or the residue tastes soapy. The carbonates also regulate acidity, and they are what gives pretzels and ramen noodles their distinctive alkaline bite and browning.
Foods commonly containing it
Baking powder and self-raising flour, cakes, scones and soda bread, ramen and other alkaline noodles, pretzels, cocoa processed by the Dutch method, and some canned vegetables.
Safety summary
Sodium carbonates are authorised in Great Britain as E 500 and sit in Group I — permitted at quantum satis, so no numerical maximum is set and use is limited to the amount needed for the technical effect.
No numerical ADI has been assigned. Sodium and carbonate are both normal constituents of the body and of food, which is the basis for the quantum satis permission. The dietary variable worth watching in bicarbonate-raised baking is sodium, not the carbonate.
Known concerns
Bicarbonate of soda contributes sodium. In heavily raised baked goods it can be a non-trivial part of the total, which matters for anyone tracking salt intake against the UK 6 g/day target.