>what are the differences between potassium carbonate and potassium
Potassium Bicarbonate, powder, food grade
Used to reduce the acidity of musts and wines. Avoid using if the pH
is above 3.5 or if you need to reduce more than a maximum of about
0.3%. It may be used close to bottling time if you cold stabilize
after using it. About 30% of the potential acid reduction occurs
during cold stabilization. It causes a greater rise in pH than calcium
carbonate for an equivalent reduction in acidity. 3.4 grams per gallon
will lower acidity by about 0.1%.
They don't list Potassium Carbonate
Potassium carbonate is often used to deacidify juice and wine instead
of calcium carbonate. However, when this material is added to wine,
the potassium content can be increased significantly. The additional
potassium can cause increases in wine pH, so potassium carbonate must
be used carefully.
Besides increasing pH, a stability problem sometimes occurs because
the potassium reacts with tartaric acid in the wine. Potassium
bitartrate is formed, and unless this material is removed, it can
precipitate out of the wine after bottling. Because of this
instability problem, potassium carbonates should not be used after
wine has been cold stabilized.
Lum did not list potassium Bicarbonate!
?I learned something today which I wanted to share with the group,
since it is a piece of info which I have not seen posted here before.
Specifically, there are 2 potassium salts which can be used to
de-acidify a must/wine:
1. The commonly refered to Potassium Bicarbonate, which is used at a
rate of 3.4g/USGal to reduce acid by -1g/L. &
2. Potassium Carbonate, which is used at a rate of 2.4g/USGal to
reduce acid by -1g/L. Additionaly, potassium carbonate can be used in
solution form. The soultion is made by combining 46g of potassium
carbonate with 100 ml of water. The addition of 5ml/USGal of this
solution will result in an acid reduction of -1g/L.
In the case of both potassium bicarbonate & potassium carbonate, the
majority of acid reduction takes place when the wine is cold
stabilized after the addition of the agents.
The benefit of potassium bicarbonate is that it tends to leave less of
a "salty" or "bitter" taste than potassium carbonate, while the
benefits of potassium carbonate are that you need to use less (30%
less) for an equal amount of de-acidification, and that it tend to
affect pH less than
Bottom line: Be aware that there are 2 distinct potassium salts used
for de-acidification & make sure that you know which one you have &
what your recommended usage rates should be?.
?The difference between these is potassium bicarbonate is a partially
neutralized form of potassium carbonate. It (KHCO3) already has one
proton, whereas K2CO3 has none. That makes K2CO3 more alkaline, and
therefore a bit less gentle than the bicarbonate.
However, I see no reason why there should be any difference between
two samples of the same wine, one of which has been acid reduced with
K2CO3 and the other with KHCO3, as long as they are titrated to the
same pH and cold stabilized to precipitate the KHT. The reaction
products are the same - CO2, H2O and KHT.
Personally, I prefer to use KOH, which is not as messy, because there
is no gaseous byproduct - just water and KHT?.
?Better yet, use Acidex, which contains a double-salt of Malic acid,
remove both Tartaric and Malic acid?.
?Seems to be some confusion about the "double salt" method of acid
When a weak base like calcium carbonate is added to wine, the calcium
carbonate combines with tartaric acid and produces calcium tartrate (a
salt), water and carbon dioxide. The calcium carbonate also combines
with malic acid and produces calcium malate (a salt), water and carbon
dioxide. But, more tartaric acid than malic acid is removed from the
because of the physical properties of the acids ( the disassociation
constants) and the salts (the solubility). In fact, most of the
tartaric acid will be removed before hardly any malic acid is removed.
The acidity of the wine will be reduced, but the acid profile will be
out of balance
(little tartaric acid and excessive much malic acid, so the TA may be
OK, but the pH will be too high).
Winemakers often use a "trick" to remove both malic acid and tartaric
acid from (high acid - high pH) wines by adding the dose of calcium
carbonate to a small portion of the wine rather than to the whole
batch. The volume of the small portion of wine is selected to produce
a pH above 4.5. At the higher pH, enough tartaric and malic ions are
in solution to form the double
salt "calcium tartrate malate." The amount of calcium carbonate and
the quantity of wine must be carefully selected to produce the double
After the treatment, the small portion of wine is added to the main
batch. In this case, both acids have been reduced, and the acid
profile of the wine is more balanced (the TA is OK and the pH is OK).
When weak bases are used to remove acid, the treated wine should
always be chilled to precipitate any remaining salts from the wine.
The term "double salt" refers to a treatment that removes both
tartaric and malic acids wine by precipitating the double salt
"calcium tartrate malate."
See "Concepts in Wine Chemistry" by Yair Margalit, page 303 and
Winemaking" by Philip Jackisch, page 108
Sometimes, grapes grown in cold climates contain too much acid. Then
winemakers often use calcium carbonates to reduce the acid content of
juice before fermentation. This material is occasionally used to
reduce the acid content of finished wines by small amounts. However,
when carbonates are used to reduce the acidity of a finished wine,
they can change wine flavors, raise pH and cause other problems.
Grapes grown in warm climates are usually low in acid, so carbonates
are seldom used with warm climate fruit?.
I heard somebody say stop!