Originally Posted by garymc
It might have been sodium bicarb that is considered less healthy.
I'm wondering if there's any difference in the taste of the wine after treatment with potassium bicarb vs potassium carb. Twice as much potassium left with the bicarb? Some people take potassium supplements. But does it leave a bitter, salty, or metallic taste?
Sorry, I just noticed your second paragraph.
Is this what your refering to: Potassium carbonate can react with malic acid (though as stated above, tartaric takes precedence) to form potassium bimalate. However, potassium bimalate is soluble in wine and will not (or may be difficult to) precipitate out.
Potassium bi/carbonate should be used carefully due to additions increasing must/wine pH (by the inevitable presence of increased potassium ions). Bench testing may be conducted on samples to ensure that the desired level of deacidification does not cause a pH shift beyond acceptable levels.
Either chemical is usually added to the entire batch, carbon dioxide is given off while the batch is well mixed, and cold stabilization is conducted several days later to encourage precipitation. The deacidified liquid can then be racked off the potassium bitartrate salt lees.
This deacidification is often conducted after fermentation, but should be used before cold stabilization so that full precipitation is achieved.
I've read conflicting articles on the pot carbonate. I have both but at the moment I'm using the bicarb for my additions, then cold stabilizing.
I've read if you don't do CS the potassium will not fall out, and can ruin your wine. But I myself, have not tried the experiment to prove this true or false.
"As with tartaric acid, for the purpose of testing for the proper additions of potassium carbonate, make a 5% solution. Put one litre of wine into a refrigerator and chill to about -3 or -4°C. Set up a few glasses with 100 ml of the chilled wine. Using one as a control, add 1, 2, 3, etc, mls. of the solution which will be the equivalent of 0.5, 1.0, 1.5, etc, g/l. Refrigerate for two hours or so stirring regularly - 7 or 8 times. Let the samples warm up to cellar temperature and taste to determine the amount to add to the batch. It is necessary to taste the wine after the potassium carbonate has been added to the glasses in order to determine whether there is a resulting flabby taste.
I have found that some wines, particularly aromatic wines lose their crispness when potassium carbonate is used even in very small amounts".