Last reviewed: 8 May 2026
Bicarbonate of soda is E500(ii) — the most familiar additive in UK kitchens
If you scan a packet of UK self-raising flour, a tin of soda bread mix, or a tray of supermarket scones and find E500 on the label, what you're looking at is not one chemical but a small family of three closely related sodium salts. They share a common backbone — a sodium cation paired with a carbonate or bicarbonate — and the European food-additive system groups them under a single E-number with three Roman-numeral subtypes.
Here's the family in plain terms:
The same three subtypes appear in food regulations across the UK, the EU and the wider Codex framework. When a UK ingredients list shows just "E500" without a Roman numeral, the manufacturer is telling you the additive is somewhere in this group — most often, in practice, E500(ii).
This is the bit worth pausing on, because it cuts through a lot of "additives are scary" instinct in one go. The little tin of bicarbonate of soda sitting in millions of UK kitchen cupboards — used for soda bread, scones, scrubbing a sink, killing a fridge smell, occasionally calming heartburn — is chemically identical to the E500(ii) on the back of a packet of supermarket scone mix. There is no difference between the "additive" version and the "kitchen ingredient" version. It's the same compound, NaHCO3, packaged for different shelves.
That makes E500(ii) one of the strangest cases in the E-number system: it's the additive most people already buy, hold, and bake with by name, but they don't realise the E-number on a food label is referring to it. Most of the unease about "E-numbers" is unease about unfamiliarity. Bicarbonate of soda has been on UK kitchen shelves for well over a century. The number plate just looks different on a finished product.
E500(ii) does several distinct jobs across UK food manufacturing, all of them rooted in two simple bits of chemistry: it releases carbon dioxide when it meets heat or acid, and it raises pH when it dissolves.
This is the headline use. Bicarbonate of soda decomposes when heated past about 80°C, releasing carbon dioxide. It also reacts with acids — buttermilk, yoghurt, lemon juice, vinegar, cream of tartar, treacle, cocoa — releasing CO2 immediately on mixing. Either way, the gas inflates the bubbles in a batter or dough, lifting the structure. That's the rise in soda bread, in scones, in drop biscuits, in gingerbread, in classic American-style cookies and pancakes.
The acid pairing matters because pure bicarb on its own, without an acid partner, leaves a soapy, slightly metallic aftertaste in the finished bake. UK recipes that call for bicarb almost always pair it with an acidic liquid or sugar source for that reason.
In some commercial bread doughs and baked goods, a small amount of E500(ii) is added not to lift the product but to nudge the pH up a touch. That changes how proteins set, how starches gelatinise, and how brown the crust gets in the oven (alkali surfaces brown more readily — part of the reason pretzels look the way they do).
Raising the pH of a wet surface partially denatures the proteins on tougher cuts of meat. A thin alkaline brine — bicarb stirred into water — left on beef, chicken or pork strips for a short window will produce a noticeably softer, more yielding bite once cooked. This is the basis of the Chinese stir-fry "velveting" technique covered below.
A minor role compared with the dedicated E551–E559 anti-caking series, but bicarb does help powders flow more freely in some blended dry mixes.
Once you start reading labels with E500 in mind, it shows up in more places than you'd guess:
Worth a paragraph because it's one of the most useful kitchen-science applications of bicarb that home cooks rarely know about. In Chinese restaurant stir-fry kitchens, tougher cuts of beef, chicken or pork are routinely velveted — the protein strips are sprinkled with a small amount of bicarbonate of soda (a quarter teaspoon per 250g is roughly typical), tossed, and left to sit for fifteen to twenty minutes before being rinsed thoroughly and patted dry.
What's happening: the alkaline surface raises the local pH high enough to partly denature the proteins on the outside of the meat. The resulting cooked texture is dramatically softer and more yielding than untreated meat from the same cut. The rinse step is essential — too much residual bicarb leaves a soapy taste and over-velvets the meat to a mushy bite. The technique is the reason restaurant stir-fry beef is reliably tender even when the cut going into the wok is the same one that would be a chewy disappointment cooked at home without it.
Sodium bicarbonate is roughly 27% sodium by weight. That sounds modest until you do the maths against the NHS reference for adult sodium intake, which is 2.4 g per day (equivalent to 6 g of salt). A level teaspoon of bicarbonate of soda is about 5 g, which works out to around 1.4 g of sodium — roughly 60% of the NHS daily reference in a single teaspoon.
For people on sodium-restricted diets — those with heart failure, certain kidney conditions, or hypertension being managed with diet — that's a meaningful number, and worth noting before reaching for bicarb-based home remedies. In a finished baked good, however, the per-portion amounts are tiny. A scone or a slice of soda bread typically contributes a fraction of the sodium that comes from the salt added to the same recipe. The high sodium content of bicarb is the practical limit on how much manufacturers can use in a given product, not toxicity.
The three E500 subtypes split duties roughly along the lines of how alkaline they are. E500(i) sodium carbonate (washing soda) is the strongest, used where you need a real shift in pH — alkaline noodles, pretzel solutions, processed cheese melt control. E500(ii) sodium bicarbonate (baking soda) is the gentler everyday workhorse, used where a small CO2 release and a modest pH nudge are enough — domestic baking, soda bread, scones, effervescent tablets. E500(iii) sodium sesquicarbonate sits between them, in specialty applications.
For a closely related raising-agent E-number that does a similar job through different chemistry, see our guide to E503 (ammonium bicarbonate / baker's ammonia) — the traditional German Hirschhornsalz still used in some thin biscuits and crispy bakes, where it leaves no residue because the gas products vent off cleanly during baking. Bicarb and ammonium bicarb solve the same broad problem (lifting a dough) with slightly different trade-offs in flavour, residue and product type.
The European Food Safety Authority re-evaluated the carbonates group in 2018. EFSA confirmed acceptable food use with the ADI listed as not specified — the regulatory shorthand quantum satis, meaning the level used should be no more than is needed to achieve the technological effect. The practical ceiling on E500 in food is the sodium content rather than any toxicity threshold. The US FDA classes sodium bicarbonate, sodium carbonate and sodium sesquicarbonate as GRAS (Generally Recognized as Such for the regulator's purposes). UK and EU rules permit the family as a raising agent, acidity regulator and anti-caking agent.
On a UK ingredients list, the additive may appear as "E500", "sodium carbonate", "sodium bicarbonate", "bicarbonate of soda", "raising agent: sodium bicarbonate", or with a subtype number — E500(i), E500(ii) or E500(iii). All of these refer to a member of this same group.
All three E500 subtypes are wholly inorganic — no animal-derived ingredients, no fermentation steps that would raise concerns. They are suitable for vegan, vegetarian, halal and kosher diets.
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