Potassium acid tartrate

E number E336CAS 868-14-4

Potassium acid tartrate is cream of tartar — the acid in baking powder, the stabiliser that lets egg whites hold a stiff peak, and the agent that stops boiled sugar crystallising.

Where it is and isn’t permitted

Status of Potassium acid tartrate by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
United StatesFood and Drug AdministrationPermitted21 CFR 184.1077retrieved 2026-09-07
Codex AlimentariusCodex Alimentarius Commission / JECFANot listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited.

What it is made from

Recovered from the crystalline deposit that forms in wine barrels and tanks during fermentation, then purified. It is a genuine by-product of winemaking.

  • Vegan
  • Vegetarian
CAS registry number
868-14-4
InChIKey
KYKNRZGSIGMXFH-ZVGUSBNCSA-M
PubChem
CID 23681127

Every name it appears under

60 recorded names. A label may use any of them.

E number

  • E336

CAS registry number

  • 868-14-4
  • 921-53-9

As it appears in regulation

  • Potassium acid tartrate

Other names

  • Acid potassium tartrate
  • Butanedioic acid 2,3-dihydroxy-, (R-(R*,R*))-, monopotassium salt
  • Butanedioic acid, 2,3-dihydroxy- (2R,3R)-, monopotassium salt
  • Butanedioic acid, 2,3-dihydroxy- (2R,3R)-, potassium salt (1:1)
  • Butanedioic acid, 2,3-dihydroxy- (theta-(theta,theta))-, monopotassium salt
  • Butanedioic acid, 2,3dihydroxy, (R(R*,R*)), monopotassium salt
  • CCRIS 7329
  • Cream of tartar
  • Cremor tartari
  • E 336
  • Faccla
  • Faccula
  • Faecla
  • Faecula
  • HSDB 1264
  • INS NO.336(I)
  • INS-336(I)
  • KYKNRZGSIGMXFH-ZVGUSBNCSA-M
  • L-(+)-Tartaric acid monopotassium salt
  • Monobasic potassium tartrate
  • Monopotassium 2,3-dihydroxybutanedioate, (R-(R*,R*))-
  • Monopotassium 2,3dihydroxybutanedioate, (R(R*,R*))
  • Monopotassium tartrate
  • Monopotassium tartrate (336(i))
  • NPT6P8P3UU
  • potassium (2R,3R)-3-carboxy-2,3-dihydroxypropanoate
  • Potassium acid salt of L(+)tartaric acid
  • Potassium acid salt of L-(+)-tartaric acid
  • Potassium acid tartrate
  • POTASSIUM ACID TARTRATE (MART.)
  • Potassium bitartrate
  • POTASSIUM BITARTRATE (II)
  • POTASSIUM BITARTRATE (USP IMPURITY)
  • POTASSIUM BITARTRATE (USP MONOGRAPH)
  • Potassium bitartrate (USP)
  • POTASSIUM BITARTRATE (USP-RS)
  • Potassium hydrogen L-tartrate
  • POTASSIUM HYDROGEN TARTRATE (EP IMPURITY)
  • POTASSIUM HYDROGEN TARTRATE (EP MONOGRAPH)
  • Potassium hydrogen tartrate (JAN)
  • POTASSIUM HYDROGEN TARTRATE [JAN]
  • Potassium L-bitartrate
  • Potassium L-tartrate
  • Potassium L-tartrate (kc4H5O6)
  • Potassium L-tartrate monobasic
  • Potassium Lbitartrate
  • Potassium Ltartrate (KC4H5O6)
  • Potassium tartrate (KHC4H4O6)
  • Potassium tartrates
  • potassium;(2R,3R)-2,3,4-trihydroxy-4-oxo-butanoate
  • Purified cream of tartar
  • Tartar
  • Tartar cream
  • Tartaric acid monopotassium salt

Systematic names

  • dipotassium (2R,3R)-2,3-dihydroxybutanedioate
  • Potassium;2,3,4-trihydroxy-4-oxobutanoate

Hazard reference values

Values set by assessing bodies. A body that has not set a value is not listed here.
TypeValuePopulationAssessed byOpinion
ADI240 mg/kg bw/dayconsumersEFSA FAF2020

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated by hand rather than machine-read, and none has been written for this substance yet.

Sources for this page

  • ecfr retrieved 2026-09-07

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable:/api/v1/additives/potassium-acid-tartrate.json