We are more than halfway through the grape harvest and still think it's summer!

Initially, the most meaningful parameter of grapes and grape juice to an aspiring amateur winemaker is brix or sugar percentage. 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.So 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: Wines with a higher pH will require more Bentonite and possibly other fining agents for good fining results. Calcium carbonate, CaCO3, used to reduce acid pre-fermentation at the rate .3-.4 grams/liter will increase the pH by approximately 0.1. This shift must be taken into consideration and is the restriction in the use of CaCO3 and the other acid reduction aids.

The pH shift will vary depending on the chemistry of the must. Must meaning the grape mess. If the initial pH of the grape is below 2.95, the shift in the pH with the use of acid reduction chemicals may not be an issue.

Acidex also shifts the pH. Potassium Bicarbonate neutralizes the acid and raises the pH of the wine even more than calcium carbonate. This can be an advantage in dealing with problem varieties with a pH below 3 and a TA above 1. Raising the pH of such wines will help soften their acid taste.

However, this can also be a major disadvantage. It is recommended only for use with wines with a pH below 3 and a T.A. above 1 to ensure that the final pH will not exceed 3.5. Maximum reduction of TA is in the .25 to .3 percent range to hopefully avoid an increase in the pH that is not advantageous. With a higher pH, a wine will also require more potassium metabisulfite.

A final pH of 3.4-3.45 at the end of the winemaking process is acceptable. A pH of 3.5-3.6 will not yield a long living wine. If your wine has strange problems, check the pH. Keep tabs on the pH.

Marcy Mitchell is a wine enthusiast and owner of Fall Bright,

The Winemakers Shoppe