Sugar and Acid Wine Adjustments

Perfectly ripe. That is how most winemakers — amateur and professional — want the grape crop to come in for every vintage. “Perfectly ripe” involves a whole host of factors. For home winemakers, the first one we usually look at is the sugar content in degrees Brix or specific gravity (SG). With some target in mind, we check the vineyard or examine the grapes we have purchased. Most grapes for dry red wines have a target somewhere in the range of 23 to 25 °Brix and most white varieties for dry or off-dry wines are targeted at about 21 to 23 °Brix. Sugar content alone does not tell the whole ripeness story. The next factor we usually check is the titratable acidity (TA) and corresponding pH. Red wine grapes are considered about right when the TA is near 0.65 g/100 mL (0.65% or 6.5 g/L). pH will ideally be in the range of 3.4 to 3.6. White grapes are generally sought with a bit more acid and corresponding lower pH: TA of 7.0 g/L or so and pH of 3.2