Cupric Citrate
Cupric Citrate (or Copper citrate) bonds with hydrogen sulphide to precipitate out of fermenting grape must and wine. Recognised by the OIV, cupric citrate is permitted for use in grape wine in over 39 countries worldwide.
Copper citrate is applied for the treatment of wine to remove fermentation and storage related off-flavours (sulphide off-flavours, flavours caused by reduction reactions, flavours caused by the presence of hydrosulfuric acid and mercaptans). The copper sulphide formed during the treatment precipitates in wine as it is a very poorly soluble compound and can be separated by filtration. Addition to the wine can be made directly or preferably by means of bentonite as a carrier material. The purity requirements of Codex resolution OENO 11/2003 apply for the bentonite used. The addition to the wine is limited (resolution OENO 1/2008), legally permitted limits of copper contents in wine must be respected.
Copper citrate dissolved in 10 % nitric acid reacts with ammonium hydroxide (R) to form a dark blue complex of tetramine copper. Heating to dryness at more than 180 °C leads to the carbonization of the citrate.
For further substance information, please see the International Oenological Codex.
Synonym(s): Copper Citrate, Cupric Citric Acid
CAS Number: 10402-15-0
E Number: Not available at this time
INS Number: Not available at this time
International Organisations
Codex Alimentarius
-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 Clarification Recommended Usage (International Code of Oenological Practices – Annex: Maximum Acceptable Limits) Maximum use level 0.01 g/L; Residual limit 1 mg/L
FIVS
Classification Category 2 – Naturally occurring in grapes and treatment residual in wine
Recommended Usage
Not available at this time
As outlined in the OIV’s International Code of Oenological Practices, Cupric citrate is used:
Copper citrate is applied for the treatment of wine to remove fermentation and storage related off-flavours (sulphide off-flavours, flavours caused by reduction reactions, flavours caused by the presence of hydrosulfuric acid and mercaptans).
Usage in Winemaking:
Cupric Citrate (or Copper citrate) bonds with hydrogen sulphide to precipitate out of fermenting grape must and wine. Residual copper will remain in solution and attention should be paid to regulatory limits. Copper citrate is also used to “pop” the fruit aroma of a wine prior to bottling. It is often used as an alternative to copper sulphate as it has a lower solubility.
See FIVS technical papers for more information - click here.
