With the development of science and technology, winemakers no longer have to draw conclusions based solely on the external signs and taste qualities of the grapes. Modern specialists use a special instrument - a refractometer - which assesses the level of sugar content in grapes, grape must, and finished wine.

This information is critically important at different stages of winemaking:

1. Determining the Optimal Time for Grape Harvesting (before the start of fermentation):

•  Maturity Measurement: A refractometer allows you to quickly and accurately determine the sugar content (measured in °Brix, °Oe, or °KMW) in the grapes on the vine. This is a key indicator of maturity. Winemakers conduct regular measurements in different parts of the vineyard to determine when the grapes have reached optimal maturity for the desired style of wine.
•  Alcohol Content Prediction: Knowing the sugar level, winemakers can predict the potential alcohol content in the wine after fermentation. This allows them to plan the fermentation process and achieve the desired alcohol level.

2. Controlling the Fermentation Process:

•  Sugar Consumption Monitoring: During fermentation, yeast converts sugar into alcohol. A refractometer is used to track the decrease in sugar levels in the grape must. This helps winemakers control the course of fermentation and ensure that the process is going correctly.
•  Determining the Moment to Stop Fermentation (if necessary): In some cases, winemakers want to stop fermentation before all the sugar has been processed to obtain a sweeter wine. A refractometer helps determine when to stop fermentation to achieve the desired level of residual sugar.

3. Evaluating the Finished Wine:

•  Determining Dryness/Sweetness: A refractometer makes it possible to determine the amount of residual sugar in the finished wine, which determines its dryness, semi-dryness, semi-sweetness, or sweetness.
•  Quality Control: Measuring residual sugar helps winemakers ensure that the wine meets the desired characteristics and quality standards.

How exactly does a winemaker use a refractometer?

1. Sample Collection: The winemaker collects several grape berries from different vines or takes a sample of grape must/wine.
2. Refractometer Preparation: The refractometer must be calibrated using distilled water (to a reading of 0).
3. Sample Application: A few drops of grape/must/wine juice are applied to the prism of the refractometer.
4. Reading the Indications: The winemaker looks into the eyepiece of the refractometer and reads the indications on the scale. The indications indicate the sugar content in percentage (°Brix), degrees Oechsle (°Oe), or degrees Klosterneuburger Mostwaage (°KMW), depending on the scale used.
5. Data Recording and Analysis: The winemaker records the data and analyzes it to make decisions about the further stages of winemaking.

Thus, a refractometer is an indispensable tool for winemakers, allowing them to control the sugar content throughout the entire winemaking process and make informed decisions to create high-quality wines.