CALCIUM CARBONATE CaCO3

CALCIUM CARBONATE CaCO3
(for juice BEFORE fermentation)

NOTE: Acid reduction with Calcium Carbonate, Potassium Bicarbonate, OR Acidex can not exceed more than a .4% total reduction either by combined or any one application. A reduction of .2 or .3 of any reducing agent may be a safer projection.

Approximately 2.5 grams of CaCO3 will reduce the acidity of 1 gallon by 0.1%

CaCO3 .3-.4 grams /liter will increase the pH by ~ 0.1 This shift must be taken into consideration and is the restriction in the use of CaCO3 and the other acid reduction aids noted above. The pH shift will vary depending on the chemistry of the must.

With a initial pH of 2.95, the addition of .3 grams/liter being equivalent to 1.13 grams/gallon (1 gallon = 3.78 liter), at the rate of 2.5 grams per gallon, will shift the pH by ~.22 resulting in a pH of around 3.17. If you have a pH meter, put it to use during any acid reduction using these additives. Do not go above a pH of 3.5; 3.4 is better for a maximum pH.

CaCo3 reduces tartaric acid first producing calcium tartrate. Not until all the tartaric acid has been neutralized will it act on malic or citric acids. Calcium malate requires 6 months of more to precipitate and is not affected by temperature. Hence the recommendation to use CaCo3 prior to fermentation. It needs a long time.

It is important to treat only a portion of one sixth or less if possible. We have always suggested treating one third of the total volume of juice, when in fact it is to your advantage to treat a lesser volume. The treatment of the least amount of juice possible can reduce the pH shift. The goal is to reduce the TA of the treated juice to 0. To calculate the amount of Calcium Carbonate needed for reduction:

1. Reduce the initial acid reading by .12 to allow for acid reduction during fermentation OR by .20 to allow for combined reduction due to fermentation and cold stabilization. (Cold stabilization is highly recommended, even though it is not required due to the use of calcium carbonate.) This figure is the “potential natural acidity.”

2. From the potential natural acidity subtract the desired total acidity. This depends on your taste. However, never go below .6 or the stability will be affected. This will yield the acidity to be neutralized by the calcium carbonate.

3. If the acidity to be neutralized is greater than .4, use the lower figure of .4 as your maximum reduction with calcium carbonate. Do not adjust more than .4%. If you adjust .4% with calcium carbonate, you will not be able to use any other acid reducing agents. You may want to consider the use of sugar water (10-15%) and or blending with a lower acid juice.

4. If the reduction is .4% and 2.5 grams will reduce the acidity of 1 gallon by 0.1%, the amount required will be 2.5 x 4 or 10 grams per gallon times the number of gallons, i.e. 5gallons (times) X 10 = 50 grams for 5 gallons. Add this amount to a portion of the entire volume. This will strip most or all of the acids from this portion.

To determine the amount of juice to be treated: Determine the acidity, by titrating, in gm/l which when expressed in tenths of a gram/100 ml will give acidity as a percentage. This value times 10 times 2.5 grams will give the amount of CaCO3 needed to completely neutralize one gallon of juice. This number is then divided into the number for the total acidity to be reduced as determined in step 4. Professional winemakers caution against an acid reduction of more than .2% because of potential pH problems.

Example: 10 gallons of Vignoles juice having an acidity of 1.1g/100 ml is to be lowered to an acidity of .9g/100 ml. The amount of CaCO3 needed is 2.5 X 2 (number of tenths to be reduced) X 10(number of gallons to be treated) = 50 grams. (2.5 grams of CaCO3 will reduce the acidity of 1 gallon by 0.1% )

The amount of CaCO3 needed to completely neutralize one gallon of Vignoles juice is 11(number of tenths) X 2.5 = 27.5 grams.

The total juice volume needed to strip most of the required acid reduction is 50/27.5 = 1.8 gallons or a little less than 1/5 of the total. Rounding up to 2 gallons or 1/5 should work fine.

OR (second example) if 5 gallons of Vignoles with an acidity of 1.1g/100ml is to be lowered to an acidity of .9g/100ml. The amount of CaCO3 needed is 2.5 X 2 (number of tenths to be reduced X 5 (number of gallons to be treated) =25 grams.

The amount of CaCO3 needed to completely neutralize one gallon of Vignoles juice (TA of 1.1g/100ml) is 11(number of tenths) X 2.5 = 27.5 grams.

The total juice volume needed to strip most of the required acid reduction is 25/27.5 = .9 gallons or shy 1 gallon or as there are 4 quarts in a gallon: 4 X .9 = 3.6 quarts.

· Add the calculated amount of calcium carbonate to the determined amount of juice slowly, over a period of 1 hour with frequent agitation.

· Allow this to settle for 24 hours and rack, adding back into the total volume. This helps to prevent excessive distortion of the entire natural acid profile.

Ferment as desired, racking 3-4 times. *Calcium tartrate is not stabilized by cold. In fact these crystals grow better at warmer temperatures around 60^O F. To protect against late Calcium Tartrate formation in the bottle, filter a wine and let it sit for 4-6 weeks and then bottle, sterile filtering if necessary.

Reference: Home Winemaking Step by Step, J Iverson, Tom and Marcy Mitchell, *Thomas Henick-Kling, Associate Professor Cornell University