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High Brix Fermentation

The Winemaker’s Think Tank: Vol 32 – “What do I do if I have a stuck fermentation?”

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! :)

Closeup of early 30's man having some wine in the middle of the day and thinking about his relationship problem. Somewhere at the bottom of the glass there is a meaning of everything that bothers him right now.

What do I do if I have a stuck fermentation?

                  Sometimes, even though we take great care as winemakers to avoid it, we can get caught with a stuck fermentation. Yeast are incredible creatures, capable of very rapid reproduction, but they do have their limiting factors. It is very important to know the limitations of the certain yeast strain that you are using for your wine. Evaluate your must’s pH to ensure that it is above 3.2, the lower pH environmental threshold for most yeast strains. Take into consideration the alcohol tolerance of the yeast that you selected. If you take the initial Brix level and multiply it by .55, you will have a pretty close estimate of your ending alcohol by volume. Make sure that you haven’t put in a yeast that is unable to handle the rising alcohol levels of the must. Another important factor to consider is the temperature of the must. All yeast strains have a preferred temperature window in which they like to work and reproduce. Because fermentation is an exothermic reaction, check your temperatures (if making reds always take a measurement under the cap) and be sure they haven’t gotten so warm that the yeast may be dying off. The opposite is also true, ensuring that your juice or must have warmed up enough to allow the yeast to begin their processing. Lastly, another important factor to  consider in the health of your fermentation is the nutrition of your yeast. Aside from the sugar that they consume, yeast also need proteins, vitamins, and minerals to complete a healthy fermentation. Using a nutrient, such as Fermaid, will give the yeast the other elements needed to properly process the juice.

                  After the careful evaluation of these factors, you may need to add a small amount of water, nutrients, or heat or cool the must/juice. A winemaker at Musto Wine Grape is happy to help you with the amounts and timing of these additions. If all of these factors have been evaluated and adjusted for, prior to fermentation, and you still have a stuck fermentation, you will need to restart the fermentation. Please contact support@juicegrape.com and a trained winemaker can help you with a restart procedure.

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.