The Winemaker’s Think Tank: Vol 29 – How do I test for Brix?

What’s the Winemaker’s Think Tank?

Every Thursday we will post about a few frequently asked questions that our winemaker has answered. If you have a winemaking question you would like to have answered, please email us at support@juicegrape.com and we will try to get into next week’s post. Cheers! 🙂

{refractometer used in vineyard for brix levels}

How do I test for Brix?

There are two ways to test for Brix in your grape juice and/or must. Prior to the addition of yeast and fermentation, one may use a hand refractometer to measure the sugar content (Brix) of the grapes. First the sampling method must be discussed. Simply taking one grape and squeezing it on the refractometer is not an accurate measurement of the entire batch, it is only reflective on the sugar content of that grape. The most accurate way to measure Brix would be to crush and process the grapes into a fermenting tub, punch down to thouroughly mix the must and allow to sit for 24 hours. This will create a more homogenous product from which to draw a sample. Using a hydrometer is simple, place a drop of grape juice on the lens of the hydrometer and lower the plastic coverslip. Hold the refractometer to your eye and look towards a bright light source. The light gets refracted by the sugar and will form an indicator line on the lens inside of the refractometer. This lens has a marked measurements column which will then give you your initial, pre-fermentation Brix level.

Once yeast has been introduced to the must and begins to excrete alcohol, the refractometer loses its accuracy. This is when the hydrometer becomes more useful in this instance. To use the hydrometer, you will also need a cylindrical container; a graduated cylinder works well (the cylinder must be taller than the hydrometer). Pour a strained sample of the must or juice into the sanitized cylinder. Put the sanitized hydrometer into the cylinder and spin it slightly to dislodge any bubbles that may cling to the sides of it. Allow it to come to rest in the juice and observe the meniscus of the liquid and where it falls on the gradients of the hydrometer. This will give you the Brix level of the fermenting wine. As the wine ferments, the Brix level will continue to drop until it is at zero.

We hope this information helps with your winemaking. If you have any follow up questions or winemaking questions in general, please email us at support@juicegrape.com.