pH
Fall Bright, The Winemakers Shoppe
Initially, the most meaningful parameter of grapes and grape juice to an aspiring winemaker is Brix or sugar percentage or degree. It is the one factor that connotes maturity. If the sugar is high, it must be ripe. The higher the sugar the riper the fruit, the more sugar the better. NOT NECESSARILY SO! Many winemakers never go beyond this way of thinking. However, as the winemaker advances, he soon learns the importance of acidity and pH.
pH is a dimension that expands the quality aspects of wine. It ties in with acidity and places limitations on use of various additives that the winemaker commonly uses. It is sometimes the reason a jug of wine goes down the drain, when everything was done correctly. This is a simplified caution regarding several products.
Product limitations:
Bentonite: Wines with a higher pH will required more Bentonite for good fining results.
Calcium
carbonate: 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 below.
The pH shift will vary depending on the chemistry of the must.
Acidex: shifts the pH, also as with calcium carbonate. Keep tabs.
Potassium Bicarbonate: Because it neutralizes the acid, potassium bicarbonate raises the pH of the wine more than calcium carbonate. This can be an advantage in dealing with problem varieties with a pH below 3.0 and a TA above 1.0. Raising the pH of such wines will help soften their acid taste. However, this can also be a major disadvantage or limitation in its use. It is recommended only for use with wines with a pH below 3.0 and a T.A. above 1.0 to insure that the final pH will not exceed 3.5. Maximum reduction of TA is in the .25 to .3% range.
A final pH of 3.4 to 3.45 may be more desirable. A pH of 3.5 or 3.6 will not yield a long living wine.