E-numbers / Acidity regulators / E336
also: Cream of tartar · Potassium bitartrate · Monopotassium tartrate · Dipotassium tartrate
The potassium salt of tartaric acid, naturally found in grapes, used to control acidity and stabilise texture in food and drink.
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Gluten-Free Oat Flour* (41%), Almonds* (21%), Coconut Oil* (20%), Coconut Flower Sugar*, Baking Powder (Cream of Tartar, Sodium Bicarbonate), Bitter Almond Extract* (Organic Aroma), *Organic
Potassium tartrates are the potassium salts of tartaric acid, an organic acid that occurs naturally in grapes, tamarind and other fruits.
Potassium tartrates are the potassium salts of tartaric acid, an organic acid that occurs naturally in grapes, tamarind and other fruits. E336 covers two forms: monopotassium tartrate (cream of tartar, E336i) and dipotassium tartrate (E336ii). Both are white crystalline powders derived from the residue left in wine barrels after fermentation.
As an acidity regulator, potassium tartrates lower and stabilise pH in food systems. In baking, monopotassium tartrate (cream of tartar) reacts with bicarbonate of soda to release carbon dioxide, giving rise to baked goods without the need for heat. It also stabilises whipped egg whites by lowering pH around the proteins, which strengthens the foam. In confectionery and wine, the tartrates help prevent crystallisation of tartaric acid and maintain a consistent acidic environment.
Most commonly found in baking powder, meringues, angel cake, and home baking recipes where cream of tartar is called for. Also used in wine production to stabilise tartrate levels, in some confectionery and hard candies, and in certain soft drinks and cordials as an acidity buffer. On a UK label it appears as 'acidity regulator (E336)', 'potassium tartrates', or in baking contexts simply as 'cream of tartar'.
Potassium tartrates contribute a small amount of dietary potassium. For most people this is nutritionally unremarkable. People with impaired kidney function who must restrict potassium intake should be aware that processed foods can accumulate potassium contributions from multiple additives, of which E336 is one. This is a general caution about potassium load in renal disease, not a specific toxicological concern with tartrate itself.
People with chronic kidney disease are advised to monitor total dietary potassium from all sources, including food additives that deliver potassium as their counter-ion.
Tartaric acid is absorbed in the small intestine and excreted largely unchanged in urine; it is not metabolised to energy substrates. The JECFA and EFSA scientific panels have reviewed tartaric acid and its salts and concluded that the acceptable daily intake is not a numerically limiting factor at typical food-use levels. No accumulation or organ toxicity has been identified in the studies reviewed.
EFSA's Panel on Food Additives and Nutrient Sources reviewed tartaric acid and tartrates (E334-337, E354) and found no toxicological concern at levels used in food.
People with chronic kidney disease who follow a low-potassium diet should account for potassium contributed by this and other potassium-containing additives. Look for 'potassium tartrates', 'cream of tartar', or 'acidity regulator (E336)' on the label.
Potassium tartrates are among the most chemically ordinary food additives in use, being the same compound that crystallises naturally on the inside of wine bottles. The science on them is long-settled: they are metabolised or excreted without accumulation, and the regulatory review completed by EFSA in 2020 raised no new questions. The only realistic dietary flag is the potassium contribution for people on medically supervised low-potassium diets, and that applies to any potassium-bearing additive, not to tartrates specifically.
No. Potassium tartrates are approved for use in the UK under the assimilated EU Regulation 1333/2008 on food additives, carried into UK law after 2020. They appear on the UK FSA's approved-additives list.
Yes. Cream of tartar is the common name for monopotassium tartrate, which is E336i, one of the two forms covered by the E336 designation. The other form, dipotassium tartrate, is E336ii.
Baking powder and baking mixes are the most common source. It is also used in meringues, some confectionery, soft drinks, cordials and grape-based products including wine. On the label it appears as 'acidity regulator (E336)', 'potassium tartrates', or 'cream of tartar'.
Yes. Potassium tartrates are derived from tartaric acid found in grape residues and other plant sources. No animal-derived ingredients are involved in production.
Last reviewed: 20 June 2026
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