Potassium tartrate or Dipotassium tartrate is a chemical compound, the potassium salt of tartaric acid. 

The name describes the structure of the molecule:

• Potassium refers to the potassium ion (K+), an alkaline metal.
• Tartrate is the tartrate ion, which is derived from tartaric acid, a type of organic acid. Tartaric acid has the chemical formula C₄H₆O₆ and, when it loses two hydrogen ions (H+), it becomes a tartrate ion (C₄H₄O₆^-2).

Description of raw materials used in production

• Tartaric acid - An organic acid found in grapes and some other fruits.
• Potassium hydroxide (KOH) or Potassium carbonate (K₂CO₃) - Source of the potassium cation.

The synthesis process takes place in different steps:

• Preparation. Aqueous solutions of tartaric acid, Rochelle salt (potassium sodium tartrate) and potassium sulphate.
• Reaction. Tartaric acid (H₂C₄H₄O₆) reacts with Rochelle salt (KNaC₄H₄O₆) and potassium sulphate (K₂SO₄) to form potassium tartrate (K₂C₄H₄O₆), sodium sulphate (Na₂SO₄) and water (H₂O).
• Precipitation. Potassium tartrate precipitates from the solution as it is less soluble in water than the other products.
• Filtration. The solution is filtered to separate the solid potassium tartrate from the liquid.
• Drying. Potassium tartrate is dried to obtain the solid potassium tartrate from the liquid.

It is not metabolized in the body and is eliminated in the urine without any side effects, however an Admissible Daily Dose of 30mg/kg body weight is indicated (1).

Food

Additive labelled E336 in the European food additives list as an acidity regulator.

• E336 (i) Monopotassium tartrate
• E336 (ii) Dipotassium tartrate

It is used in the food industry as a leavening agent.

Cosmetics

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

Other uses

Potassium tartrate is also found in: inks and toners, perfumes and fragrances, pharmaceuticals, washing & cleaning products and personal care products and fertilisers.

Applications

Baking - Used as a stabilizer for egg whites, helping them maintain their structure when whipped.

Candy making - Acts as a leavening agent when combined with baking soda.

Cleaning - Used as a natural cleaning agent, often combined with vinegar or lemon juice.

Winemaking - Deposits at the bottom of barrels during wine production.

Metal treatment - Used in electroplating.

Chemical industry - Can be used in the production of other tartrate salts.

Studies

Obstructive nephropathy induced with DL-potassium hydrogen tartratein F344 rats.  Inoue K, Morikawa T, Takahashi M, Yoshida M, Ogawa K.  J Toxicol Pathol. 2015 Apr;28(2):89-97. doi: 10.1293/tox.2014-0058. Epub 2015 Feb 9.

Effects of plant food potassium salts (citrate, galacturonate or tartrate)on acid-base status and digestive fermentations in rats.  Sabboh H, Coxam V, Horcajada MN, Rémésy C, Demigné C.  Br J Nutr. 2007 Jul;98(1):72-7.

Molecular Formula: C₄H₅KO₆

Molecular Weight: 188.18

CAS: 868-14-4

EC Number: 212-769-1

Synonyms:

• L(+)-Potassium hydrogen tartrate
• Potassium hydrogen tartrate
• potassium d-tartrate
• 1-Potassium hydrogentartrate
• potassium hydrogentartrate
• kaliumtartrat
• Monopotassium tartrate
• rel-Potassium (2S,3S)-2,3-dihydroxysuccinate(1:1)
• POTASSIUM 3-CARBOXY-2,3-DIHYDROXYPROPANOATE
• KSC657E1T
• NSC155080

References_____________________________________________________________________

EFSA Panel on Food Additives and Flavourings (FAF); Younes M, Aquilina G, Castle L, Engel KH, Fowler P, Frutos Fernandez MJ, Fürst P, Gürtler R, Gundert-Remy U, Husøy T, Mennes W, Shah R, Waalkens-Berendsen I, Wölfle D, Boon P, Tobback P, Wright M, Aguilera J, Rincon AM, Tard A, Moldeus P. Re-evaluation of l(+)-tartaric acid (E 334), sodium tartrates (E 335), potassium tartrates (E 336), potassium sodium tartrate (E 337) and calcium tartrate (E 354) as food additives. EFSA J. 2020 Mar 11;18(3):e06030. doi: 10.2903/j.efsa.2020.6030.