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! 🙂

How do I know if fermentation is complete?

It is often easy to see visual signs of fermentation:  from activity in the airlock, bubbles, and the formation of a cap to the aromas of yeast and carbon dioxide, the wonders of fermentation are succinct observation.  But how does the home winemaker know when the fermentation is complete? The simplest way of seeing if fermentation is complete is to taste the wine and observe if there is any sweetness to it. If there is still sugar that you can taste, the yeast have not yet completed their job. The most accurate and scientific way of seeing if fermentation is complete is to take a measurement of the Brix via a hydrometer. A hydrometer is a glass instrument that reads sugar content via the hydrometers buoyancy in wine juice. The juice sample should always be placed into a sanitary, cylindrical shaped vessel. As the wine ferments, yeast consumer sugar and excrete alcohol, making a thinner, less dense liquid. At the beginning of fermentation, the hydrometer will not sink very far into the wine. The sugars within the juice make it thicker and the hydrometer will float on top of the juice. As fermentation progresses the new wine becomes less dense and sugary, allowing the hydrometer to sink down into the liquid. When the fermentation is complete, the hydrometer will sink down into the liquid to the 0 mark, if not farther. When reading the hydrometer, spin it slightly in the cylinder to dislodge any bubbles that may cling to the sides of the hydrometer. Observe where the meniscus of the wine falls on the gradients of the hydrometer. This will give you your sugar level in degrees Brix of the fermenting wine. When the hydrometer sinks to zero or below, the fermentation is complete and you can rack the wine.

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.