Agriculture Reference
In-Depth Information
BALANCING SUGAR AND ACID
You will take two measurements to determine when to pick your grapes.
1. The sugar content, measured by taste (the old-fashioned way) or in terms of
Brix, as measured by a refractometer or hydrometer: 1 degree Brix is 1 gram of sugar
in 100 grams of solution (grape juice). The range for grape sugar is:
→ From 20 to 25 Brix for regular table wines
→ From 26 to 33 or more Brix for late harvest or sweet wines (port, sherry, and
the like)
2. The pH levels, measured with a pH meter:
→ A range of 3.1 to 3.3 for white wines
→ A range of 3.4 to 3.5 for red wines
Grapes below 3.1 will be too acidic. Above 3.5, the wine will be subject to oxida-
tion and bacteria.
You may also want to measure acid levels, which we'll consider next.
Wine Acidity
Although most of your work in the vineyard has been to manage the sugar levels in
the grapes, it's also important for growers and winemakers to understand and manage acid
levels in the grapes.
There are several types of acid in wine, including primarily tartaric acid, malic acid,
and citric acid. The levels of acid in the grapes should be different depending on the style
of wine you plan to make, and for individual tastes. The measurement of acidity that that
indicates the strength of the acid in the grapes is the pH. It is measured using a titration
kit or pH meter. TA, or titratable acidity, represents acidity as a percentage of volume. You
can use the pH meter to measure pH but not TA; for this you need to use a lab for testing,
or buy a relatively expensive and complicated setup to test TA. Home winemakers may
not measure this factor with such precision, but commercial wineries do, and you can have
your grapes tested by a commercial lab if you choose. A pH meter, on the other hand, is
inexpensive and easy to use.
Appropriate acid levels are:
