Last reviewed: 8 May 2026
The most common food preservative in UK fridges — what it stops growing
Open the fridge. The yoghurt, the cheese spread, the bottled mayo, the hummus, the sweet white wine, the soft drinks — pull a few labels and you'll see E202 again and again. Potassium sorbate is the workhorse mould-and-yeast inhibitor of UK food preservation. It's so common that "preservative" on a chilled product label is, more often than not, this one ingredient. Here's what it actually does, why manufacturers reach for it instead of E211 sodium benzoate or E220 sulphur dioxide, and what the published research says about the rare allergic reactions.
E202 is the potassium salt of sorbic acid — chemical formula C6H7KO2. In its pure form it's a white-to-cream crystalline powder, highly water-soluble. That solubility is why food manufacturers prefer the potassium salt over the parent acid (E200): you can dissolve it straight into the water phase of a yoghurt, a soft drink or a sauce without needing solvents.
Sorbic acid itself was first isolated in 1859 by the German chemist August Hofmann from the unripe berries of the rowan tree (Sorbus aucuparia) — which is where the name comes from. Trace amounts occur naturally in a handful of fruits. The E202 used in UK food today is synthesised industrially through a reaction of crotonaldehyde and ketene; the end molecule is identical to the natural one.
The sorbate family on UK labels:
EFSA evaluates these four together as a group, since the active species in food is the same: undissociated sorbic acid, which forms in equilibrium with the salt at the pH of most preserved products.
E202 is an antimicrobial — it stops things growing. Specifically, it works against:
Mechanism: sorbic acid (the active form) crosses the microbial cell membrane in its undissociated state and disrupts enzyme function and membrane integrity. The cell can no longer maintain the proton gradient it needs to produce energy. Effectively, the mould or yeast spore lands on the surface of the food, can't grow, and dies.
This only works in a particular pH range. E202 is most effective at pH 4–6 — the natural pH of most fermented dairy, dressings, sauces, dips and soft drinks. Above pH 6 it loses potency rapidly because the acid dissociates into the inactive sorbate ion. That pH window is the single most important fact about it on a label, because it explains why E202 turns up in some categories and not others.
It's worth being clear about what potassium sorbate isn't, because that's why some preserved foods still use older, more controversial preservatives.
Pull labels in any UK supermarket and these are the categories where potassium sorbate dominates:
On a UK ingredients list it'll appear as "E202", "potassium sorbate", or "preservative: potassium sorbate" — all three are valid under UK and EU labelling rules.
The choice of preservative is mostly about pH, secondary about taste and stability, and only occasionally about cost. Here's how E202 stacks up against the other three you'll see on UK labels:
Benzoate is most active at pH below 4.5; sorbate is active up to pH 6. That difference decides the category. Soft drinks (pH around 3) often use both — benzoate as the main workhorse, sorbate widening the pH safety net. Dairy products (pH 5–6) use sorbate, because benzoate barely works at that pH. If you see a yoghurt or a cream cheese preserved with E211 alone, the chemistry shouldn't really hold; the manufacturer is relying heavily on cold chain.
Sulphites do two jobs sorbate can't — antioxidant and antimicrobial — and they're irreplaceable in winemaking. They also have a documented asthma-trigger profile: roughly 5–10% of asthmatics react to dietary sulphites, which is why "contains sulphites" is one of the 14 mandatory UK allergen declarations. Sorbate has no equivalent issue. For products where antioxidant action isn't needed (dairy, sauces, dips), sorbate sidesteps the asthma question entirely.
Natural preservatives work, but they're more expensive, less stable, often add colour or flavour, and need higher concentrations. Sorbate is colourless, near-tasteless at the use levels permitted in food (≤0.1%), and stable across heat treatments. That combination is hard to match with a botanical extract.
Allergic reactions to potassium sorbate are rare but published. The bulk of case reports come from cosmetic use — sorbate is also widely used as a preservative in lotions, creams and sunscreens, where it sits in prolonged direct contact with skin. The reported reaction is contact dermatitis: localised redness, itching, sometimes a hive-like rash where the product was applied. Patch-test rates in dermatitis clinics suggest somewhere in the low single percent of patch-tested patients react.
Ingestion-related reactions are less common in the literature. There are individual case reports of urticaria (hives) after eating high-sorbate products in sensitive individuals, but no large-scale evidence of food-allergy-like reactions in the general population. Sorbate is not on the EU/UK list of 14 mandatory allergens (the list that includes milk, egg, gluten, sulphites, sesame, etc.), and there's no UK regulatory requirement to flag it specifically.
If someone has a confirmed sorbate sensitivity from a cosmetic patch test, that doesn't automatically mean they'll react to it in food — the dose, the skin-versus-gut route and the contact time are all different. Anyone with confirmed sensitivity should discuss it with their GP or dermatologist.
"Preservative" on a UK label can mean very different chemistry, and shoppers often lump them together. It's worth being explicit about what potassium sorbate isn't connected to:
Clearing this up matters because someone scanning a yoghurt label and seeing "preservative" can otherwise assume the worst — when in this case the chemistry is well-characterised and unrelated to the high-profile additive concerns.
EFSA (UK/EU): the European Food Safety Authority re-evaluated the sorbate group (E200, E202, E203) in 2015 and set a group Acceptable Daily Intake of 3 mg per kg of body weight per day. For a 70 kg adult that's roughly 210 mg/day. EFSA's assessment found no toxicological concern at typical exposure levels. Following EU exit, UK FSA-administered food additive law mirrors the EFSA framework.
US: the FDA classifies potassium sorbate as Generally Recognized As Safe (GRAS) for use as a preservative.
Maximum permitted levels in food: typically 0.1–0.3% by weight depending on category, set by EU Regulation 1333/2008 and retained UK law. The use levels manufacturers actually use are usually well below the legal cap, because sorbate works at low concentrations.
Potassium sorbate as supplied to UK food manufacturers is synthesised industrially, with no animal-derived inputs in the standard production route. It's typically classed as suitable for vegans, vegetarians, halal diets and kosher diets. As always, the certification status of the finished product depends on the rest of the recipe and the certifier — check the per-product label or contact the manufacturer if a specific certification matters.
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