Tartrate, Potassium Sodium

Synonym(s): Rochelle salt, Seignette’s salt 
CAS Number: 304-59-6 
E Number: 337 
INS Number: 337

International Organisations

Codex Alimentarius 

-Classification, Food Category, Functional Class and Recommended Usage is not available at this time. 

International Organisation of Vine and Wine (OIV) 

-Classification, Food Category, Functional Class and Recommended Usage is not available at this time. 

FIVS 

Classification Category 2 – Naturally occurring in grapes and treatment residual in wine 

Recommended Usage 

Please refer to the Joint FAO/WHO Expert Committee on Food Additives’ (JECFA) “acceptable daily intake” (ADI) for recommended usage.

Tartaric acid is naturally occurring in grapes and adjusting the acidity of must and wine is an important part of the winemaking process. The addition of acid to juice, must or wine will decrease the pH and increase the Titratable Acidity (TA) of the wine. The low pH will make SO2 more effective which will help prevent oxidation and bacterial infections, will increase colour intensity and ageing potential of the wine. 

Sometimes a must will have a TA that is too low, and this can be raised with potassium tartrate. Due to the presence of large quantities of solids in red musts, less of the salt will be needed than for whites. It is helpful to add a fraction of what is estimated to be needed, dissolved in some juice and well mixed. The must can then be re-tested and adjusted accordingly. 

To illustrate: 

• A 1.0 g/L addition of Potassium Tartrate will increase the TA by about 1.0 g/L and will decrease the pH by 0.1 unit. 
• In a must for making a white wine, the TA should be roughly in the range from 7 to 9.5 g/L but can go higher. 
• In musts for dessert or sparkling wines, the TA can be well over 10 g/L. In red wine musts, TA should generally be in the range from 6 to 8 g/L. 

Additionally, potassium tartrate is added to wine to inhibit the formation of potassium bitartrate crystals which are commonly formed in bottled wine. The presence of potassium bitartrate crystals in wine is not a safety or wine quality issue but rather one of the aesthetics.

See FIVS technical papers for more information - click here.