Agriculture Reference
In-Depth Information
→ A range of 0.65 to 0.85 TA for white wines (dry white wine 0.65 to 0.85; sweet
white wine 0.70 to 0.85)
→ A range of 0.60 to 0.80 for red wines (dry red wine 0.60 to 0.70; sweet red wine
0.65 to 0.80)
There is a relationship between sugar, TA, and pH level. For instance, the perfect
Cabernet Sauvignon balance of these three factors is 22 to 25 Brix, 0.75 TA, and a pH of
3.4. If all those numbers are in the correct range, the grapes will produce a good wine for
the variety with little intervention. If the numbers are too far outside the ideal range, the
only way to make adjustments is during the winemaking process, but you are less likely to
produce a quality wine.
It's a good idea to develop a testing process from veraison to harvest that determines
Brix and pH. Along with grape color and taste, these two measurements are usually suf-
ficient. You can also consult with the winemaker if you are selling your grapes. At some
point you may be able to accomplish what the grand winemakers do—simply taste the
grape in the vineyard and know when to pick.
MEASURING BRIX
Refractometers are not expensive, but they do contain fairly sophisticated optical equip-
ment. Essentially, the refractometer uses a prism assembly to read the amount of sugar in
a liquid sample that is sandwiched between a daylight plate and the prism. The reading, in
Brix, is indicated on a scale.
Calibrate your refractometer following the manufacturer's instructions (refractomet-
ers are calibrated to work at a specific temperature). Once the instrument has been calib-
rated, clean the daylight plate and the top of the main prism assembly with a soft, damp
cloth.
Pick a cluster of grapes and squeeze the juice into a sterile bowl, then strain the juice.
Place 2 or 3 drops of the juice onto the top of the prism. Close the daylight plate and let
the juice spread out over the prism for about 30 seconds. Hold the instrument up to a nat-
ural source of daylight and look into it, focusing the eyepiece as needed. Read the scale
and write down the Brix. Until you become very familiar with the instrument, be sure to
take several readings. Always clean your refractometer with water after use and store it in
a clean, dry place.
A hydrometer is a glass cylinder with a weighted bulb that measures the density of
grape juice or must, which correlates to the amount of sugar in the liquid. You place the
hydrometer in a beaker of must, and it will float at a certain level which is read according
to a Brix scale on the floating cylinder. The hydrometer is a helpful tool to determine the
Brix level, but it is not very portable and you need enough juice to fill up a beaker in order
to get an accurate reading; thus it is more helpful for winemakers than for grape growers.
