Cabernet PH Adjustment Information

Some research findings on adjusting PH.  But before we decide to adjust, we should verify the PH reading again. Our last PH adjustment didn't work out well partially because of a bad PH reading because the meter was going out. However, we are not surprised by the high PH reading because of the unusually high sugar/brix in the cabernet.  We should do a 2 point calibration with the meter. We should stir the must well and then filter some juice thru a coffee filter to ensure it's clean. We may also want to measure T.A.

 

The risks of not adjusting the PH are:

1. The wine will loose color.

2. The wine will become microbally unstable and will spoil.

3. To protect the wine we will have to use very high levels of Sulfites.

 

Adjusting PH:

The book "Techniques in Home Winemaking" advises against using acid blends because they contain citric acid which will make the wine taste sour. Instead use Tartaric acid.

 

You adjust the PH based on the volume of wine, not must.  In general estimate gallons of wine = 60% of total must volume.

 

We estimated 71G of must in each microbin. That would be about 42G of wine, or 159 liters.

We estimated 104G of must in the macrobin. That would be 62G of wine, or 235 liters.

 

We estimate that the average PH of the combined wines will be around 3.8, realizing it will increase by 0.1 to 0.2 after Malolactic Fermentation. We would like to get it down to 3.6, but may want to be conservative and just shoot for  PH of 3.7. Although remember that PH will rise again after MLF. So a 0.2 adjustment may be the minimum we want to do. We will have to discuss the options and decide. In general the less we do to the wine, the better.

 

PH Adjustment Formula & Amounts:

1 gram per liter of wine reduces the PH by 0.1 units.

 

159 grams of tartaric acid would lower the PH in the a small microbins by 0.1.

235 grams would lower PH in the large macrobin by 0.1.

 

The references state there are 5 grams of tartaric acid in 1tsp. So 0.2 tsp = 1 gram.

 

SMALL MICROBIN: 0.2 * 159 = 31.8 tsp (10.6 TBSP or 5.3 OZ) to adjust PH down to 3.7.

 

LARGE MACROBIN: 0.2 * 235 = 47 tsp (15 2/3 TBSP or 7.8 OZ).to adjust PH down to 3.7.