Metatartaric Acid
When added to the wine, metatartaric acid retards crystal growth and inhibits the precipitation of KHT. Recognised by the OIV, metatartaric acid is permitted for use in grape wine in over 40 countries worldwide.
The name metatartaric acid applies to the product obtained by dehydrating L-tartaric acid at a temperature of 150-170 °C under atmospheric pressure or under a reduced pressure. This product can retard tartaric precipitation in the bottle. Its effectiveness in preventing tartaric precipitation is directly related to the rate of esterification. The quantity in which it is used in wines is restricted. The primary constituents of the product are the ditartaric monoester and diester in variable proportions based on the combination of two molecules of tartaric acid with water loss, mixed with variable quantities of non-esterified tartaric acid, pyruvic acid and small quantities of poorly known polyester acids.
This product exists in crystalline masses or in powder form with a white or greater or lesser yellowish color. It has a faint odor of toast or caramel and is very deliquescent. It is highly soluble in water and alcohol and rapidly hydrolyzed in aqueous solution at 100 °C, but much more slowly at cold temperatures. For further substance information, please see the International Oenological Codex.
Synonym(s): Ditartaric acid
CAS Number: 39469-81-3
E Number: 353
INS Number: 353
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)
-Food Category Wine (grape) Functional Class Stabiliser Metartaric acid: additive Recommended Usage (International Code of Oenological Practices – Annex: Maximum Acceptable Limits) Amount used in the treatment: 10 g/h
FIVS
Classification Category 4 – Not 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.
As outlined in the OIV’s International Code of Oenological Practices, metatartaric acid is used: To retard tartaric precipitation in the bottle.
Usage in Winemaking:
The presence of potassium tartrate crystals in wine is not a safety or wine quality issue but rather one of aesthetics. There are various stabilisation treatments used to prevent their formation in wine bottles. One method involves the use of metatartaric acid, which is an approved food additive for this purpose in most wine-producing markets.
See FIVS technical papers for more information - click here.
