Brix (or Degrees Brix or °Brix) is a fancy term for one way of measuring the sugar content of something like a grape juice (Brix = the sugar content of an aqueous solution). Sugar content is an important number to know for the wine maker, as sugar in grapes will be turned into alcohol in the finished wine. Sugar content is also an important (but not the only) component in deciding when to harvest the grapes. I will dispense with theory, and place myself fully in the practical by expounding on the actual measurement and some uses of Brix by the wine maker. For information junkies you my click here for more details about Brix than you probably ever wanted to know.

There are different tools, which vary in their accuracy, to measure Brix. But at this time of year I use a hand refractometer to quickly and approximately measure Brix directly in the vineyard in order to get an overall idea of vineyard status. In other words, I use this tool:

Hand Refractometer

Hand Refractometer

The operation is quite simple, which is shown step by step below in pictures and text.

Add some grape juice to measure Brix.

Add some grape juice to measure Brix. This is done by opening the hinged cover over the front bevel of the refractometer and squeezing out the juice onto the crystal window (the blue part in the photo) of about six or more grape berries (Pinot Gris in this case) picked at random while walking through the vineyard. Using and mixing the juice from several berries on the bevel will give a better estimate of the overall Brix level of the entire vineyard than just a single berry.

Gently close the hinged cover over the grape juice.

Gently close the hinged cover over the grape juice. This will squeeze out some juice but gives a constant thickness of the juice for measurement.

Hold the refractometer in the sunlight and look through the eye piece at the other end.

Hold the refractometer in the sunlight and look through the eye piece at the other end.

Degrees Brix shown in the refractometer.

You should see in the refractometer a scale like shown in the photo above. The Degrees Brix is shown in the left scale of the viewer, which is showing a value of about 17.8°. (Note: °Brix is labeled in this scale as %mas Sacch. Since I purchased this refractometer in Switzerland all the markings are typical of the German wine industry, which also explains the Oechsle Scale on the right, which is an alternate method used mainly in German speaking countries for measuring sugar content and ripeness of grapes).

Now that I have taken a measurement of Brix, which again is just a measure of sugar content, what does it mean?

First of all, a Brix value in of itself can be used as a relative measure of ripeness. You may have seen reported elsewhere (and excessively) that the so called “optimal” Brix is around 24°. This is actually not quite true. Rather the real optimal value depends on a number of factors including the wine being grown and the region where it is grown. For example, the “optimal” Brix for a California red grape, and for a wine maker who wants to create a high alcohol wine, of 24° (or more) may be considered “optimal“. But for a white wine, the “optimal” range may be more modest, and can have a lower range of 21°-23°. For a Mosel Riesling, the Brix may fall only within 19°-20° at harvest (or even less), but the grapes will still arguably make one of the best white wines in the world (proving that Brix is not the only measure of ripeness and what defines a quality wine). However, you can see from the refractometer measurement above of 17.8° the grapes are still several degrees away from an optimal white wine range, and solely based on a Brix measurement, are not yet ripe.

Second, Brix will relate to the amount of potential alcohol in the final wine. The term “potential alcohol” is used since the actual amount of alcohol will also vary depending on various factors, such as if the wine is fully fermented to consume all the available sugar (i.e. fermented to dryness). And to further complicate matters, there are actually different formula one can use to convert from Brix to potential alcohol. Indeed, the method used can even very depending on if it is a white or red wine being fermented.

If there is any lesson, or take home message, to learn from wine making it is the realization that the term “it depends” appears often in the process.

From experience with our white wines the following table works reasonable well for us as an estimator (so note, your observed values may differ for your wine):

Brix Potential Alcohol
17.0 10.0
18.0 10.6
19.0 11.2
20.0 11.8
21.0 12.4
22.0 13.0
23.0 13.6
24.0 14.2

So Brix, and other factors such as acidity (to be discussed in a later article) play a variable and dynamic role role in wine making. Trying to balance them is all part of the joy, the fun, and let’s call it “the art“, of wine making.