For grapes that require acid reductions of more than 2%.
In order to maintain a balance of tartaric and malic acids, it is recommended to use this method.
Otherwise potassium carbonate and cold stabilizarion can be used.
We are collecting data on the effects of calcium carbonate additions and the affect on pH and TA.
We are also experimenting with deacidifying higher ratios and adding tartaric acid to correct tartaric/malic acid ratios. Please consider sharing your 'double salt deacidification' data with us (use 'Your Winery Journal', and select 'Deacidification data for research purposes'). We hope to contribute some valuable tools to our subscribers. (* all data is completely confidential).
A portion of juice is removed and completely deacidified, (both tartaric and malic acid are removed)
In a well ventilated room, slowly add the calculated quantity of must to a slurry of the Calcium Carbonate over ~30 minutes, while vigourously mixing (to release the carbon dioxide). Let it settle for a further 30-60 minutes. Blend this back (ideally through a coarse filter) leaving the precipitated salts behind.
SO2 additions may be added now.
Best done prior to fermentation, to avoid detrimental oxidation.
Wait a minimum of 30 days (preferably 90+ days) before bottling, to allow the Calcium and Potassium Salts to precipitate, ideally with some weeks below 5C (40F) and some weeks above 10C (50F). Calium Malate Salts precipitation can occur in bottles if adequate time is not allowed.
To treat crushed red grapes, either:
a) Estimate the final yield of pressed wine. Collect the fraction of juice to be deacidified and treat as above.
b) treat after fermentation, as above, risking some oxidative effects.
The volume to treat is calculated with the following formula:
volume (L) = ( ( current TA - target TA ) * total volume ) / current TA
mass (kg) = ( ( current TA - target TA ) * total volume ) * ( ( 1 / 150.087 ) / 10 )
Where:
150.087 = the molecular mass of tartaric acid
10 = is simply a conversion to make the mass express in kg