Acid Corrections:

The acid content of your wine has a dramatic effect on its taste and mouthfeel. We check the acid levels of our crushed grapes and correct it as necessary. We take further acid tests when the wine is racked to barrels and again just before bottling. Any acid corrections will also adjust the pH, although the amount of pH adjustment is not as predictable as the acid adjustment.

Formula for calculating acid levels of juice by titration:
Acid level = 75 x ml of NaOH used x NaOH normality/ml of juice used (assuming 10 ml of juice and 0.1N NaOH, = 0.75 x ml of NaOH used)

Once the acid levels are known, they can be adjusted using the following formulas. For large adjustments, perform in several small steps instead of one large adjustment.

Acid Addition:

3.6 grams tartaric acid/gallon will raise acid level 0.10 grams/L and lower pH approx. 0.10

Acid Reduction:

2.5 grams calcium carbonate (CaCO3)/gallon will lower acid 0.10 grams/L and raise pH approximately 0.10

3.4 grams potassium bicarbonate (KHCO3)/gallon will lower acid 0.10 grams/L and raise pH approximately 0.10

Sugar Correction:

There comes a time in every winemaker’s career when grapes are picked before sugar levels reach the desired optimum level. This happens frequently in Europe, so winemakers add sugar to bring the brix level to optimum. In the U.S., it is illegal for a commercial winery to add sugar to raise the brix level of their musts. As amateurs, we are not bound by these rules. Following is the formula for adding sugar. We hope you never have to use it!

Sugar additions (Chaptalization):

Lbs. of sugar required = (gallons of wine x 8.35 lbs/gallon x brix change desired)/(100-desired brix.)

(add sugar in three parts: twice at primary, once as you enter secondary)

Note: 2 ½ cups plain white sugar = one pound